\input texinfo.tex    @c -*-texinfo-*-
@c $Id: texinfo.txi,v 1.225 2008/09/07 22:47:46 karl Exp $
@c Ordinarily, Texinfo files have the extension .texi.  But texinfo.texi
@c clashes with texinfo.tex on 8.3 filesystems, so we use texinfo.txi.

@c Everything between the start/end of header lines will be passed by
@c Emacs's {texinfo,makeinfo}-format region commands.  See the `start of
@c header' node for more info.
@c %**start of header

@c makeinfo and texinfo.tex ignore all text before @setfilename.
@c
@c Ordinarily, the setfilename argument ends with .info.  But
@c texinfo.info-13 is too long for 14-character filesystems.
@setfilename texinfo

@c Automake automatically updates version.texi to @set VERSION and
@c @set UPDATED to appropriate values.
@include version.texi
@settitle GNU Texinfo @value{VERSION}

@c Define a new index for options.
@defcodeindex op
@c Put everything except function (command, in this case) names in one
@c index (arbitrarily chosen to be the concept index).
@syncodeindex op cp
@syncodeindex vr cp
@syncodeindex pg cp

@paragraphindent 2
@c finalout

@comment %**end of header

@copying
This manual is for GNU Texinfo (version @value{VERSION}, @value{UPDATED}),
a documentation system that can produce both online information and a
printed manual from a single source.

Copyright @copyright{} 1988, 1990, 1991, 1992, 1993, 1995, 1996, 1997,
1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover Texts being ``A GNU Manual'',
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled ``GNU Free Documentation
License.''

(a) The FSF's Back-Cover Text is: ``You are free to copy and modify
this GNU Manual.  Buying copies from GNU Press supports the FSF in
developing GNU and promoting software freedom.''
@end quotation
@end copying

@dircategory Texinfo documentation system
@direntry
* Texinfo: (texinfo).           The GNU documentation format.
* install-info: (texinfo)Invoking install-info. Update info/dir entries.
* texi2dvi: (texinfo)Format with texi2dvi.      Print Texinfo documents.
* texi2pdf: (texinfo)PDF Output.                PDF output for Texinfo.
* pdftexi2dvi: (texinfo)PDF Output.             PDF output for Texinfo.
* texindex: (texinfo)Format with tex/texindex.  Sort Texinfo index files.
* makeinfo: (texinfo)Invoking makeinfo.         Translate Texinfo source.
@end direntry

@c Before release, run C-u C-c C-u C-a (texinfo-all-menus-update with a
@c prefix arg).  This updates the node pointers, which texinfmt.el needs.

@c Set smallbook if printing in smallbook format so the example of the
@c smallbook font is actually written using smallbook; in bigbook, a kludge
@c is used for TeX output.  Do this through the -t option to texi2dvi,
@c so this same source can be used for other paper sizes as well.
@c smallbook
@c set smallbook
@c @@clear smallbook

@c If you like blank pages, add through texi2dvi -t.
@c setchapternewpage odd

@c Currently undocumented command, 5 December 1993:
@c nwnode          (Same as node, but no warnings; for `makeinfo'.)


@shorttitlepage GNU Texinfo

@titlepage
@title Texinfo
@subtitle The GNU Documentation Format
@subtitle for Texinfo version @value{VERSION}, @value{UPDATED}

@author Robert J. Chassell
@author Richard M. Stallman

@c Include the Distribution inside the titlepage so
@c that headings are turned off.

@page
@vskip 0pt plus 1filll
@insertcopying

@sp 1
Published by the Free Software Foundation @*
51 Franklin St, Fifth Floor @*
Boston, MA 02110-1301 @*
USA @*
ISBN 1-882114-67-1 @c for version 4.0, September 1999.
@c ISBN 1-882114-65-5 is for version 3.12, March 1998.
@c ISBN 1-882114-64-7 is for edition 2.24 of November 1996.
@c ISBN 1-882114-63-9 is for edition 2.20 of 28 February 1995.

@sp 1
Cover art by Etienne Suvasa.
@end titlepage


@summarycontents
@contents


@ifnottex
@node Top
@top Texinfo

This manual is for GNU Texinfo (version @value{VERSION}, @value{UPDATED}),
a documentation system that can produce both online information and a
printed manual from a single source.

The first part of this master menu lists the major nodes in this Info
document, including the @@-command and concept indices.  The rest of
the menu lists all the lower level nodes in the document.

@end ifnottex

@menu
* Copying Conditions::            Your rights.
* Overview::                      Texinfo in brief.
* Texinfo Mode::                  Using the GNU Emacs Texinfo mode.
* Beginning a File::              What is at the beginning of a Texinfo file?
* Ending a File::                 What is at the end of a Texinfo file?
* Structuring::                   Creating chapters, sections, appendices, etc.
* Nodes::                         Writing nodes, the basic unit of Texinfo.
* Menus::                         Writing menus.
* Cross References::              Writing cross references.
* Marking Text::                  Marking words and phrases as code,
                                    keyboard input, meta-syntactic
                                    variables, and the like.
* Quotations and Examples::       Block quotations, examples, etc.
* Lists and Tables::              Itemized or numbered lists, and tables.
* Special Displays::              Floating figures and footnotes.
* Indices::                       Creating indices.
* Insertions::                    Inserting @@-signs, braces, etc.
* Breaks::                        Forcing or preventing line and page breaks.
* Definition Commands::           Describing functions and the like uniformly.
* Conditionals::                  Specifying text for only some output cases.
* Internationalization::          Supporting languages other than English.
* Defining New Texinfo Commands:: User-defined macros and aliases.
* Hardcopy::                            Output for paper, with @TeX{}.
* Creating and Installing Info Files::  Details on Info output.
* Generating HTML::               Details on HTML output.

* Command List::                  All the Texinfo @@-commands.
* Tips::                          Hints on how to write a Texinfo document.
* Sample Texinfo Files::          Complete examples, including full texts.
* Include Files::                 How to incorporate other Texinfo files.
* Headings::                      How to write page headings and footings.
* Catching Mistakes::             How to find formatting mistakes.
* GNU Free Documentation License::Copying this manual.
* Command and Variable Index::    A menu containing commands and variables.
* General Index::                 A menu covering many topics.

@detailmenu
 --- The Detailed Node Listing ---

Overview of Texinfo

* Reporting Bugs::              Submitting effective bug reports.
* Using Texinfo::               Create printed or online output.
* Output Formats::              Overview of the supported output formats.
* Info Files::                  What is an Info file?
* Printed Books::               Characteristics of a printed book or manual.
* Formatting Commands::         @@-commands are used for formatting.
* Conventions::                 General rules for writing a Texinfo file.
* Comments::                    Writing comments and ignored text in general.
* Minimum::                     What a Texinfo file must have.
* Six Parts::                   Usually, a Texinfo file has six parts.
* Short Sample::                A short sample Texinfo file.
* History::                     Acknowledgements, contributors and genesis.

Using Texinfo Mode

* Texinfo Mode Overview::       How Texinfo mode can help you.
* Emacs Editing::               Texinfo mode adds to GNU Emacs' general
                                  purpose editing features.
* Inserting::                   How to insert frequently used @@-commands.
* Showing the Structure::       How to show the structure of a file.
* Updating Nodes and Menus::    How to update or create new nodes and menus.
* Info Formatting::             How to format for Info.
* Printing::                    How to format and print part or all of a file.
* Texinfo Mode Summary::        Summary of all the Texinfo mode commands.

Updating Nodes and Menus

* Updating Commands::           Five major updating commands.
* Updating Requirements::       How to structure a Texinfo file for
                                  using the updating command.
* Other Updating Commands::     How to indent descriptions, insert
                                  missing nodes lines, and update
                                  nodes in sequence.

Beginning a Texinfo File

* Sample Beginning::            A sample beginning for a Texinfo file.
* Texinfo File Header::         The first lines.
* Document Permissions::        Ensuring your manual is free.
* Titlepage & Copyright Page::  Creating the title and copyright pages.
* Contents::                    How to create a table of contents.
* The Top Node::                Creating the `Top' node and master menu.
* Global Document Commands::    Affecting formatting throughout.
* Software Copying Permissions::  Ensure that you and others continue to
                                   have the right to use and share software.

Texinfo File Header

* First Line::                  The first line of a Texinfo file.
* Start of Header::             Formatting a region requires this.
* setfilename::                 Tell Info the name of the Info file.
* settitle::                    Create a title for the printed work.
* End of Header::               Formatting a region requires this.

Document Permissions

* copying::                     Declare the document's copying permissions.
* insertcopying::               Where to insert the permissions.

Title and Copyright Pages

* titlepage::                   Create a title for the printed document.
* titlefont center sp::         The @code{@@titlefont}, @code{@@center},
                                 and @code{@@sp} commands.
* title subtitle author::       The @code{@@title}, @code{@@subtitle},
                                 and @code{@@author} commands.
* Copyright::                   How to write the copyright notice and
                                 include copying permissions.
* end titlepage::               Turn on page headings after the title and
                                 copyright pages.
* headings on off::             An option for turning headings on and off
                                 and double or single sided printing.

The `Top' Node and Master Menu

* Top Node Example::
* Master Menu Parts::

Global Document Commands

* documentdescription::         Document summary for the HTML output.
* setchapternewpage::           Start chapters on right-hand pages.
* paragraphindent::             Specify paragraph indentation.
* firstparagraphindent::        Suppress indentation of the first paragraph.
* exampleindent::               Specify environment indentation.

Ending a Texinfo File

* Printing Indices & Menus::    How to print an index in hardcopy and
                                 generate index menus in Info.
* File End::                    How to mark the end of a file.

Chapter Structuring

* Tree Structuring::            A manual is like an upside down tree @dots{}
* Structuring Command Types::   How to divide a manual into parts.
* makeinfo top::                The @code{@@top} command, part of the `Top' node.
* chapter::
* unnumbered & appendix::
* majorheading & chapheading::
* section::
* unnumberedsec appendixsec heading::
* subsection::
* unnumberedsubsec appendixsubsec subheading::
* subsubsection::               Commands for the lowest level sections.
* Raise/lower sections::        How to change commands' hierarchical level.

Nodes

* Two Paths::                   Different commands to structure
                                 Info output and printed output.
* Node Menu Illustration::      A diagram, and sample nodes and menus.
* node::                        Creating nodes, in detail.
* makeinfo Pointer Creation::   Letting makeinfo determine node pointers.
* anchor::                      Defining arbitrary cross-reference targets.

The @code{@@node} Command

* Node Names::                  How to choose node and pointer names.
* Writing a Node::              How to write an @code{@@node} line.
* Node Line Tips::              Keep names short.
* Node Line Requirements::      Keep names unique, without @@-commands.
* First Node::                  How to write a `Top' node.
* makeinfo top command::        How to use the @code{@@top} command.

Menus

* Menu Location::               Menus go at the ends of short nodes.
* Writing a Menu::              What is a menu?
* Menu Parts::                  A menu entry has three parts.
* Less Cluttered Menu Entry::   Two part menu entry.
* Menu Example::                Two and three part menu entries.
* Other Info Files::            How to refer to a different Info file.

Cross References

* References::                  What cross references are for.
* Cross Reference Commands::    A summary of the different commands.
* Cross Reference Parts::       A cross reference has several parts.
* xref::                        Begin a reference with `See' @dots{}
* Top Node Naming::             How to refer to the beginning of another file.
* ref::                         A reference for the last part of a sentence.
* pxref::                       How to write a parenthetical cross reference.
* inforef::                     How to refer to an Info-only file.
* uref::                        How to refer to a uniform resource locator.
* cite::                        How to refer to books not in the Info system.

@code{@@xref}

* Reference Syntax::            What a reference looks like and requires.
* One Argument::                @code{@@xref} with one argument.
* Two Arguments::               @code{@@xref} with two arguments.
* Three Arguments::             @code{@@xref} with three arguments.
* Four and Five Arguments::     @code{@@xref} with four and five arguments.

Marking Words and Phrases

* Indicating::                  How to indicate definitions, files, etc.
* Emphasis::                    How to emphasize text.

Indicating Definitions, Commands, etc.

* Useful Highlighting::         Highlighting provides useful information.
* code::                        Indicating program code.
* kbd::                         Showing keyboard input.
* key::                         Specifying keys.
* samp::                        A literal sequence of characters.
* verb::                        A verbatim sequence of characters.
* var::                         Indicating metasyntactic variables.
* env::                         Indicating environment variables.
* file::                        Indicating file names.
* command::                     Indicating command names.
* option::                      Indicating option names.
* dfn::                         Specifying definitions.
* abbr::                        Indicating abbreviations.
* acronym::                     Indicating acronyms.
* indicateurl::                 Indicating a World Wide Web reference.
* email::                       Indicating an electronic mail address.

Emphasizing Text

* emph & strong::               How to emphasize text in Texinfo.
* Smallcaps::                   How to use the small caps font.
* Fonts::                       Various font commands for printed output.

Quotations and Examples

* Block Enclosing Commands::    Different constructs for different purposes.
* quotation::                   Writing a quotation.
* example::                     Writing an example in a fixed-width font.
* verbatim::                    Writing a verbatim example.
* verbatiminclude::             Including a file verbatim.
* lisp::                        Illustrating Lisp code.
* small::                       Examples in a smaller font.
* display::                     Writing an example in the current font.
* format::                      Writing an example without narrowed margins.
* exdent::                      Undo indentation on a line.
* flushleft & flushright::      Pushing text flush left or flush right.
* noindent::                    Preventing paragraph indentation.
* indent::                      Forcing paragraph indentation.
* cartouche::                   Drawing rounded rectangles around examples.

Lists and Tables

* Introducing Lists::           Texinfo formats lists for you.
* itemize::                     How to construct a simple list.
* enumerate::                   How to construct a numbered list.
* Two-column Tables::           How to construct a two-column table.
* Multi-column Tables::         How to construct generalized tables.

Making a Two-column Table

* table::                       How to construct a two-column table.
* ftable vtable::               Automatic indexing for two-column tables.
* itemx::                       How to put more entries in the first column.

@code{@@multitable}: Multi-column Tables

* Multitable Column Widths::    Defining multitable column widths.
* Multitable Rows::             Defining multitable rows, with examples.

Special Displays

* Floats::                      Figures, tables, and the like.
* Images::                      Including graphics and images.
* Footnotes::                   Writing footnotes.

Floats

* float::                       Producing floating material.
* caption shortcaption::        Specifying descriptions for floats.
* listoffloats::                A table of contents for floats.

Inserting Images

* Image Syntax::
* Image Scaling::

Footnotes

* Footnote Commands::           How to write a footnote in Texinfo.
* Footnote Styles::             Controlling how footnotes appear in Info.

Indices

* Index Entries::               Choose different words for index entries.
* Predefined Indices::          Use different indices for different kinds
                                 of entries.
* Indexing Commands::           How to make an index entry.
* Combining Indices::           How to combine indices.
* New Indices::                 How to define your own indices.

Combining Indices

* syncodeindex::                How to merge two indices, using @code{@@code}
                                 font for the merged-from index.
* synindex::                    How to merge two indices, using the
                                 default font of the merged-to index.

Special Insertions

* Atsign Braces Comma::         Inserting @@ and @{@} and ,.
* Inserting Quote Characters::  Inserting left and right quotes, in code.
* Inserting Space::             How to insert the right amount of space
                                 within a sentence.
* Inserting Accents::           How to insert accents and special characters.
* Inserting Quotation Marks::   How to insert quotation marks.
* Dots Bullets::                How to insert dots and bullets.
* TeX and copyright::           How to insert the @TeX{} logo
                                 and the copyright symbol.
* euro::                        How to insert the Euro currency symbol.
* pounds::                      How to insert the pounds currency symbol.
* textdegree::                  How to insert the degrees symbol.
* minus::                       How to insert a minus sign.
* geq leq::                     How to insert greater/less-than-or-equal signs.
* math::                        How to format a mathematical expression.
* Click Sequences::             Inserting GUI usage sequences.
* Glyphs::                      How to indicate results of evaluation,
                                 expansion of macros, errors, etc.

Inserting @@ and @{@} and @comma{}

* Inserting an Atsign::
* Inserting Braces::
* Inserting a Comma::

Inserting Space

* Not Ending a Sentence::       Sometimes a . doesn't end a sentence.
* Ending a Sentence::           Sometimes it does.
* Multiple Spaces::             Inserting multiple spaces.
* frenchspacing::               Specifying end-of-sentence spacing.
* dmn::                         How to format a dimension.

Inserting Ellipsis and Bullets

* dots::                        How to insert dots @dots{}
* bullet::                      How to insert a bullet.

Inserting @TeX{} and Legal Symbols: @copyright{}, @registeredsymbol{}

* tex::                         The @TeX{} logos.
* copyright symbol::            The copyright symbol (c in a circle).
* registered symbol::           The registered symbol (R in a circle).

Glyphs for Examples

* Glyphs Summary::
* result::                      How to show the result of expression.
* expansion::                   How to indicate an expansion.
* Print Glyph::                 How to indicate printed output.
* Error Glyph::                 How to indicate an error message.
* Equivalence::                 How to indicate equivalence.
* Point Glyph::                 How to indicate the location of point.

Glyphs Summary

* result::
* expansion::
* Print Glyph::
* Error Glyph::
* Equivalence::
* Point Glyph::

Forcing and Preventing Breaks

* Break Commands::              Summary of break-related commands.
* Line Breaks::                 Forcing line breaks.
* - and hyphenation::           Helping @TeX{} with hyphenation points.
* allowcodebreaks::             Controlling line breaks within @@code text.
* w::                           Preventing unwanted line breaks in text.
* tie::                         Inserting an unbreakable but varying space.
* sp::                          Inserting blank lines.
* page::                        Forcing the start of a new page.
* group::                       Preventing unwanted page breaks.
* need::                        Another way to prevent unwanted page breaks.

Definition Commands

* Def Cmd Template::            Writing descriptions using definition commands.
* Def Cmd Continuation Lines::  Continuing the heading over source lines.
* Optional Arguments::          Handling optional and repeated arguments.
* deffnx::                      Group two or more `first' lines.
* Def Cmds in Detail::          Reference for all the definition commands.
* Def Cmd Conventions::         Conventions for writing definitions.
* Sample Function Definition::  An example.

The Definition Commands

* Functions Commands::          Commands for functions and similar entities.
* Variables Commands::          Commands for variables and similar entities.
* Typed Functions::             Commands for functions in typed languages.
* Typed Variables::             Commands for variables in typed languages.
* Data Types::                  The definition command for data types.
* Abstract Objects::            Commands for object-oriented programming.

Object-Oriented Programming

* Variables: Object-Oriented Variables.
* Methods: Object-Oriented Methods.

Conditionally Visible Text

* Conditional Commands::        Text for a given format.
* Conditional Not Commands::    Text for any format other than a given one.
* Raw Formatter Commands::      Using raw formatter commands.
* set clear value::             Variable tests and substitutions.
* Conditional Nesting::         Using conditionals inside conditionals.

@code{@@set}, @code{@@clear}, and @code{@@value}

* set value::                   Expand a flag variable to a string.
* ifset ifclear::               Format a region if a flag is set.
* value Example::               An easy way to update edition information.

Internationalization

* documentlanguage::            Declaring the current language.
* documentencoding::            Declaring the input encoding.

Defining New Texinfo Commands

* Defining Macros::             Defining and undefining new commands.
* Invoking Macros::             Using a macro, once you've defined it.
* Macro Details::               Limitations of Texinfo macros.
* alias::                       Command aliases.
* definfoenclose::              Customized highlighting.

Formatting and Printing Hardcopy

* Use TeX::                     Use @TeX{} to format for hardcopy.
* Format with tex/texindex::    How to format with explicit shell commands.
* Format with texi2dvi::        A simpler way to format.
* Print with lpr::              How to print.
* Within Emacs::                How to format and print from an Emacs shell.
* Texinfo Mode Printing::       How to format and print in Texinfo mode.
* Compile-Command::             How to print using Emacs's compile command.
* Requirements Summary::        @TeX{} formatting requirements summary.
* Preparing for TeX::           What to do before you use @TeX{}.
* Overfull hboxes::             What are and what to do with overfull hboxes.
* smallbook::                   How to print small format books and manuals.
* A4 Paper::                    How to print on A4 or A5 paper.
* pagesizes::                   How to print with customized page sizes.
* Cropmarks and Magnification:: How to print marks to indicate the size
                                 of pages and how to print scaled up output.
* PDF Output::                  Portable Document Format output.
* Obtaining TeX::               How to Obtain @TeX{}.

Creating and Installing Info Files

* Creating an Info File::
* Installing an Info File::

Creating an Info File

* makeinfo advantages::         @code{makeinfo} provides better error checking.
* Invoking makeinfo::           How to run @code{makeinfo} from a shell.
* makeinfo options::            Specify fill-column and other options.
* Pointer Validation::          How to check that pointers point somewhere.
* makeinfo in Emacs::           How to run @code{makeinfo} from Emacs.
* texinfo-format commands::     Two Info formatting commands written
                                 in Emacs Lisp are an alternative
                                 to @code{makeinfo}.
* Batch Formatting::            How to format for Info in Emacs Batch mode.
* Tag and Split Files::         How tagged and split files help Info
                                 to run better.

Installing an Info File

* Directory File::              The top level menu for all Info files.
* New Info File::               Listing a new Info file.
* Other Info Directories::      How to specify Info files that are
                                 located in other directories.
* Installing Dir Entries::      How to specify what menu entry to add
                                 to the Info directory.
* Invoking install-info::       @code{install-info} options.

Generating HTML

* HTML Translation::       Details of the HTML output.
* HTML Splitting::         How HTML output is split.
* HTML CSS::               Influencing HTML output with Cascading Style Sheets.
* HTML Xref::              Cross-references in HTML output.

HTML Cross-references

* Link Basics:       HTML Xref Link Basics.
* Node Expansion:    HTML Xref Node Name Expansion.
* Command Expansion: HTML Xref Command Expansion.
* 8-bit Expansion:   HTML Xref 8-bit Character Expansion.
* Mismatch:          HTML Xref Mismatch.

@@-Command List

* Command Syntax::    General syntax for varieties of @@-commands.

Sample Texinfo Files

* Short Sample Texinfo File::
* GNU Sample Texts::
* Verbatim Copying License::
* All-permissive Copying License::

GNU Free Documentation License

Include Files

* Using Include Files::         How to use the @code{@@include} command.
* texinfo-multiple-files-update::  How to create and update nodes and
                                     menus when using included files.
* Include Files Requirements::  @code{texinfo-multiple-files-update} needs.
* Sample Include File::         A sample outer file with included files
                                     within it; and a sample included file.
* Include Files Evolution::     How use of the @code{@@include} command
                                     has changed over time.

Page Headings

* Headings Introduced::         Conventions for using page headings.
* Heading Format::              Standard page heading formats.
* Heading Choice::              How to specify the type of page heading.
* Custom Headings::             How to create your own headings and footings.

Formatting Mistakes

* makeinfo Preferred::          @code{makeinfo} finds errors.
* Debugging with Info::         How to catch errors with Info formatting.
* Debugging with TeX::          How to catch errors with @TeX{} formatting.
* Using texinfo-show-structure::  How to use @code{texinfo-show-structure}.
* Using occur::                 How to list all lines containing a pattern.
* Running Info-Validate::       How to find badly referenced nodes.

Finding Badly Referenced Nodes

* Using Info-validate::         How to run @code{Info-validate}.
* Unsplit::                     How to create an unsplit file.
* Tagifying::                   How to tagify a file.
* Splitting::                   How to split a file manually.

@end detailmenu
@end menu

@c Reward readers for getting to the end of the menu :).
@c Contributed by Arnold Robbins.
@quotation
Documentation is like sex: when it is good, it is very, very good; and
when it is bad, it is better than nothing.
---Dick Brandon
@end quotation


@node Copying Conditions
@unnumbered Texinfo Copying Conditions
@cindex Copying conditions
@cindex Conditions for copying Texinfo

The programs currently being distributed that relate to Texinfo include
@code{makeinfo}, @code{info}, @code{texindex}, and @file{texinfo.tex}.
These programs are @dfn{free}; this means that everyone is free to use
them and free to redistribute them on a free basis.  The Texinfo-related
programs are not in the public domain; they are copyrighted and there
are restrictions on their distribution, but these restrictions are
designed to permit everything that a good cooperating citizen would want
to do.  What is not allowed is to try to prevent others from further
sharing any version of these programs that they might get from you.

Specifically, we want to make sure that you have the right to give away
copies of the programs that relate to Texinfo, that you receive source
code or else can get it if you want it, that you can change these
programs or use pieces of them in new free programs, and that you know
you can do these things.

To make sure that everyone has such rights, we have to forbid you to
deprive anyone else of these rights.  For example, if you distribute
copies of the Texinfo related programs, you must give the recipients all
the rights that you have.  You must make sure that they, too, receive or
can get the source code.  And you must tell them their rights.

Also, for our own protection, we must make certain that everyone finds
out that there is no warranty for the programs that relate to Texinfo.
If these programs are modified by someone else and passed on, we want
their recipients to know that what they have is not what we distributed,
so that any problems introduced by others will not reflect on our
reputation.

The precise conditions of the licenses for the programs currently being
distributed that relate to Texinfo are found in the General Public
Licenses that accompany them.  This manual specifically is covered by
the GNU Free Documentation License (@pxref{GNU Free Documentation
License}).


@node Overview
@chapter Overview of Texinfo
@cindex Overview of Texinfo
@cindex Texinfo overview

@dfn{Texinfo}@footnote{The first syllable of ``Texinfo'' is pronounced
like ``speck'', not ``hex''.  This odd pronunciation is derived from,
but is not the same as, the pronunciation of @TeX{}.  In the word
@TeX{}, the @samp{X} is actually the Greek letter ``chi'' rather than
the English letter ``ex''.  Pronounce @TeX{} as if the @samp{X} were the
last sound in the name `Bach'; but pronounce Texinfo as if the @samp{x}
were a `k'.  Spell ``Texinfo'' with a capital ``T'' and the other
letters in lower case.}  is a documentation system that uses a single
source file to produce both online information and printed output.  This
means that instead of writing two different documents, one for the
online information and the other for a printed work, you need write only
one document.  Therefore, when the work is revised, you need revise only
that one document.

Manuals for most GNU packages are written in Texinfo, and available
online at @url{http://www.gnu.org/doc}.

@menu
* Reporting Bugs::              Submitting effective bug reports.
* Using Texinfo::               Create printed or online output.
* Output Formats::              Overview of the supported output formats.
* Info Files::                  What is an Info file?
* Printed Books::               Characteristics of a printed book or manual.
* Formatting Commands::         @@-commands are used for formatting.
* Conventions::                 General rules for writing a Texinfo file.
* Comments::                    Writing comments and ignored text in general.
* Minimum::                     What a Texinfo file must have.
* Six Parts::                   Usually, a Texinfo file has six parts.
* Short Sample::                A short sample Texinfo file.
* History::                     Acknowledgements, contributors and genesis.
@end menu


@node Reporting Bugs
@section Reporting Bugs

@cindex Bugs, reporting
@cindex Suggestions for Texinfo, making
@cindex Reporting bugs
We welcome bug reports and suggestions for any aspect of the Texinfo system,
programs, documentation, installation, anything.  Please email them to
@email{bug-texinfo@@gnu.org}.  You can get the latest version of Texinfo
from @uref{ftp://ftp.gnu.org/gnu/texinfo/} and its mirrors worldwide.

@cindex Checklist for bug reports
For bug reports, please include enough information for the maintainers
to reproduce the problem.  Generally speaking, that means:

@itemize @bullet
@item the version number of Texinfo and the program(s) or manual(s) involved.
@item hardware and operating system names and versions.
@item the contents of any input files necessary to reproduce the bug.
@item a description of the problem and samples of any erroneous output.
@item any unusual options you gave to @command{configure}.
@item anything else that you think would be helpful.
@end itemize

When in doubt whether something is needed or not, include it.  It's
better to include too much than to leave out something important.

@cindex Patches, contributing
Patches are most welcome; if possible, please make them with
@samp{@w{diff -c}} (@pxref{Top,, Overview, diff, Comparing and Merging
Files}) and include @file{ChangeLog} entries (@pxref{Change Log,,,
emacs, The GNU Emacs Manual}), and follow the existing coding style.


@node Using Texinfo
@section Using Texinfo

@cindex Using Texinfo in general
@cindex Texinfo, introduction to
@cindex Introduction to Texinfo

Using Texinfo, you can create a printed document (via the @TeX{}
typesetting system) the normal features of a book, including chapters,
sections, cross references, and indices.  From the same Texinfo source
file, you can create an Info file with special features to make
documentation browsing easy.  You can also create from that same
source file an HTML output file suitable for use with a web browser,
or an XML file.  See the next section (@pxref{Output Formats}) for
details and the exact commands to generate output from the source.

@TeX{} works with virtually all printers; Info works with virtually all
computer terminals; the HTML output works with virtually all web
browsers.  Thus Texinfo can be used by almost any computer user.

@cindex Source file format
A Texinfo source file is a plain ASCII file containing text
interspersed with @dfn{@@-commands} (words preceded by an @samp{@@})
that tell the typesetting and formatting programs what to do.  You can
edit a Texinfo file with any text editor, but it is especially
convenient to use GNU Emacs since that editor has a special mode,
called Texinfo mode, that provides various Texinfo-related features.
(@xref{Texinfo Mode}.)

You can use Texinfo to create both online help and printed manuals;
moreover, Texinfo is freely redistributable.  For these reasons, Texinfo
is the official documentation format of the GNU project.  More
information is available at the @uref{http://www.gnu.org/doc/, GNU
documentation web page}.


@node Output Formats
@section Output Formats
@cindex Output formats
@cindex Back-end output formats

Here is a brief overview of the output formats currently supported by
Texinfo.

@table @asis
@item Info
@cindex Info output
(Generated via @command{makeinfo}.)  This format is essentially a
plain text transliteration of the Texinfo source.  It adds a few
control characters to separate nodes and provide navigational
information for menus, cross-references, indices, and so on.  See the
next section (@pxref{Info Files}) for more details on this format.
The Emacs Info subsystem (@pxref{Top,,Getting Started,info, Info}),
and the standalone @command{info} program (@pxref{Top
,, Info Standalone, info-stnd, GNU Info}), among others, can read these
files.  @xref{Creating and Installing Info Files}.

@item Plain text
@cindex Plain text output
(Generated via @command{makeinfo --no-headers}.)  This is almost the
same as Info output, except the navigational control characters are
omitted.  Also, standard output is used by default.

@item HTML
@cindex HTML output
@cindex W3 consortium
@cindex Mozilla
@cindex Lynx
@cindex Emacs-W3
(Generated via @command{makeinfo --html}.)  This is the Hyper Text
Markup Language that has become the most commonly used language for
writing documents on the World Wide Web.  Web browsers, such as
Mozilla, Lynx, and Emacs-W3, can render this language online.  There
are many versions of HTML; @command{makeinfo} tries to use a subset
of the language that can be interpreted by any common browser.  For
details of the HTML language and much related information, see
@uref{http://www.w3.org/MarkUp/}.  @xref{Generating HTML}.

@item DVI
@cindex DVI output
@pindex dvips
@pindex xdvi
(Generated via @command{texi2dvi}.)  This DeVice Independent binary
format is output by the @TeX{} typesetting program
(@uref{http://tug.org}).  This is then read by a DVI `driver', which
writes the actual device-specific commands that can be viewed or
printed, notably Dvips for translation to PostScript (@pxref{Invoking
Dvips,,, dvips, Dvips}) and Xdvi for viewing on an X display
(@uref{http://sourceforge.net/projects/xdvi/}).  @xref{Hardcopy}.

Be aware that the Texinfo language is very different from and much
stricter than @TeX{}'s usual languages, plain @TeX{} and @LaTeX{}.
For more information on @TeX{} in general, please see the book
@cite{@TeX{} for the Impatient}, available from
@uref{http://savannah.gnu.org/projects/teximpatient}.

@item PDF
@cindex PDF output
@cindex Beebe, Nelson
@pindex pdftex
(Generated via @command{texi2dvi --pdf} or @command{texi2pdf}.)  This
format was developed by Adobe Systems for portable document
interchange, based on their previous PostScript language.  It can
represent the exact appearance of a document, including fonts and
graphics, and supporting arbitrary scaling.  It is intended to be
platform-independent and easily viewable, among other design goals;
@uref{http://tug.org/TUGboat/Articles/tb22-3/tb72beebe-pdf.pdf} has
some background.  Texinfo uses the @command{pdftex} program, a variant
of @TeX{}, to output PDF; see
@uref{http://tug.org/applications/pdftex}.  @xref{PDF Output}.

@item XML
@cindex XML output
@cindex DTD, for Texinfo XML
@pindex texinfo.dtd
(Generated via @command{makeinfo --xml}.)  XML is a generic syntax
specification usable for any sort of content (see, for example,
@uref{http://www.w3.org/XML/}).  The @command{makeinfo} XML output,
unlike all the formats above, interprets very little of the Texinfo
source.  Rather, it merely translates the Texinfo markup commands into
XML syntax, for processing by further XML tools.  The particular
syntax output is defined in the file @file{texinfo.dtd} included in
the Texinfo source distribution.

@item Docbook
@cindex Docbook output
(Generated via @command{makeinfo --docbook}.)  This is an XML-based
format developed some years ago, primarily for technical
documentation.  It therefore bears some resemblance, in broad
outlines, to Texinfo.  See @uref{http://www.docbook.org}.  If you want
to convert from Docbook @emph{to} Texinfo, please see
@uref{http://docbook2X.sourceforge.net}.

@end table

@cindex Man page output, not supported
From time to time, proposals are made to generate traditional Unix man
pages from Texinfo source.  However, because man pages have a very
strict conventional format, generating a good man page requires a
completely different source than the typical Texinfo applications of
writing a good user tutorial and/or a good reference manual.  This
makes generating man pages incompatible with the Texinfo design goal
of not having to document the same information in different ways for
different output formats.  You might as well just write the man page
directly.

@pindex help2man
@cindex O'Dea, Brendan
Man pages still have their place, and if you wish to support them, you
may find the program @command{help2man} to be useful; it generates a
traditional man page from the @samp{--help} output of a program.  In
fact, this is currently used to generate man pages for the programs in
the Texinfo distribution.  It is GNU software written by Brendan
O'Dea, available from @uref{ftp://ftp.gnu.org/gnu/help2man/}.

@cindex Output formats, supporting more
@cindex SGML-tools output format
If you are a programmer and would like to contribute to the GNU project
by implementing additional output formats for Texinfo, that would be
excellent.  But please do not write a separate translator texi2foo for
your favorite format foo!  That is the hard way to do the job, and makes
extra work in subsequent maintenance, since the Texinfo language is
continually being enhanced and updated.  Instead, the best approach is
modify @code{makeinfo} to generate the new format.


@node Info Files
@section Info Files
@cindex Info files

An Info file is a Texinfo file formatted so that the Info documentation
reading program can operate on it.  (@code{makeinfo}
and @code{texinfo-format-buffer} are two commands that convert a Texinfo file
into an Info file.)

Info files are divided into pieces called @dfn{nodes}, each of which
contains the discussion of one topic.  Each node has a name, and
contains both text for the user to read and pointers to other nodes,
which are identified by their names.  The Info program displays one node
at a time, and provides commands with which the user can move to other
related nodes.

@xref{Top,,, info, GNU Info}, for more information about using Info.

Each node of an Info file may have any number of child nodes that
describe subtopics of the node's topic.  The names of child
nodes are listed in a @dfn{menu} within the parent node; this
allows you to use certain Info commands to move to one of the child
nodes.  Generally, an Info file is organized like a book.  If a node
is at the logical level of a chapter, its child nodes are at the level
of sections; likewise, the child nodes of sections are at the level
of subsections.

All the children of any one parent are linked together in a
bidirectional chain of `Next' and `Previous' pointers.  The `Next'
pointer provides a link to the next section, and the `Previous' pointer
provides a link to the previous section.  This means that all the nodes
that are at the level of sections within a chapter are linked together.
Normally the order in this chain is the same as the order of the
children in the parent's menu.  Each child node records the parent node
name as its `Up' pointer.  The last child has no `Next' pointer, and the
first child has the parent both as its `Previous' and as its `Up'
pointer.@footnote{In some documents, the first child has no `Previous'
pointer.  Occasionally, the last child has the node name of the next
following higher level node as its `Next' pointer.}

The book-like structuring of an Info file into nodes that correspond
to chapters, sections, and the like is a matter of convention, not a
requirement.  The `Up', `Previous', and `Next' pointers of a node can
point to any other nodes, and a menu can contain any other nodes.
Thus, the node structure can be any directed graph.  But it is usually
more comprehensible to follow a structure that corresponds to the
structure of chapters and sections in a printed book or report.@refill

In addition to menus and to `Next', `Previous', and `Up' pointers, Info
provides pointers of another kind, called references, that can be
sprinkled throughout the text.  This is usually the best way to
represent links that do not fit a hierarchical structure.@refill

Usually, you will design a document so that its nodes match the
structure of chapters and sections in the printed output.  But
occasionally there are times when this is not right for the material
being discussed.  Therefore, Texinfo uses separate commands to specify
the node structure for the Info file and the section structure for the
printed output.@refill

Generally, you enter an Info file through a node that by convention is
named `Top'.  This node normally contains just a brief summary of the
file's purpose, and a large menu through which the rest of the file is
reached.  From this node, you can either traverse the file
systematically by going from node to node, or you can go to a specific
node listed in the main menu, or you can search the index menus and then
go directly to the node that has the information you want.  Alternatively,
with the standalone Info program, you can specify specific menu items on
the command line (@pxref{Top,,, info, Info}).

If you want to read through an Info file in sequence, as if it were a
printed manual, you can hit @key{SPC} repeatedly, or you get the whole
file with the advanced Info command @kbd{g *}.  (@inforef{Advanced,
Advanced Info commands, info}.)@refill

@c !!! dir file may be located in one of many places:
@c     /usr/local/emacs/info            mentioned in info.c DEFAULT_INFOPATH
@c     /usr/local/lib/emacs/info        mentioned in info.c DEFAULT_INFOPATH
@c     /usr/gnu/info                    mentioned in info.c DEFAULT_INFOPATH
@c     /usr/local/info
@c     /usr/local/lib/info
The @file{dir} file in the @file{info} directory serves as the
departure point for the whole Info system.  From it, you can reach the
`Top' nodes of each of the documents in a complete Info system.@refill

@cindex URI syntax for Info
If you wish to refer to an Info file in a URI, you can use the
(unofficial) syntax exemplified in the following.  This works with
Emacs/W3, for example:
@example
info:///usr/info/emacs#Dissociated%20Press
info:emacs#Dissociated%20Press
info://localhost/usr/info/emacs#Dissociated%20Press
@end example

The @command{info} program itself does not follow URIs of any kind.


@node Printed Books
@section Printed Books
@cindex Printed book and manual characteristics
@cindex Manual characteristics, printed
@cindex Book characteristics, printed
@cindex Texinfo printed book characteristics
@cindex Characteristics, printed books or manuals

@cindex Knuth, Donald
A Texinfo file can be formatted and typeset as a printed book or manual.
To do this, you need @TeX{}, a powerful, sophisticated typesetting
program written by Donald Knuth.@footnote{You can also use the
@pindex texi2roff@r{, unsupported software}
@uref{ftp://tug.org/texi2roff.tar.gz, @code{texi2roff}} program if you
do not have @TeX{}; since Texinfo is designed for use with @TeX{},
@code{texi2roff} is not described here.  @code{texi2roff} is not part of
the standard GNU distribution and is not maintained or up-to-date with
all the Texinfo features described in this manual.}

A Texinfo-based book is similar to any other typeset, printed work: it
can have a title page, copyright page, table of contents, and preface,
as well as chapters, numbered or unnumbered sections and subsections,
page headers, cross references, footnotes, and indices.@refill

You can use Texinfo to write a book without ever having the intention
of converting it into online information.  You can use Texinfo for
writing a printed novel, and even to write a printed memo, although
this latter application is not recommended since electronic mail is so
much easier.@refill

@TeX{} is a general purpose typesetting program.  Texinfo provides a
file @file{texinfo.tex} that contains information (definitions or
@dfn{macros}) that @TeX{} uses when it typesets a Texinfo file.
(@file{texinfo.tex} tells @TeX{} how to convert the Texinfo @@-commands
to @TeX{} commands, which @TeX{} can then process to create the typeset
document.)  @file{texinfo.tex} contains the specifications for printing
a document.  You can get the latest version of @file{texinfo.tex} from
the Texinfo home page, @uref{http://www.gnu.org/software/texinfo/}.

In the United States, documents are most often printed on 8.5 inch by 11
inch pages (216@dmn{mm} by 280@dmn{mm}); this is the default size.  But
you can also print for 7 inch by 9.25 inch pages (178@dmn{mm} by
235@dmn{mm}, the @code{@@smallbook} size; or on A4 or A5 size paper
(@code{@@afourpaper}, @code{@@afivepaper}).  (@xref{smallbook, ,
Printing ``Small'' Books}.  Also, see @ref{A4 Paper, ,Printing on A4
Paper}.)

By changing the parameters in @file{texinfo.tex}, you can change the
size of the printed document.  In addition, you can change the style in
which the printed document is formatted; for example, you can change the
sizes and fonts used, the amount of indentation for each paragraph, the
degree to which words are hyphenated, and the like.  By changing the
specifications, you can make a book look dignified, old and serious, or
light-hearted, young and cheery.

@TeX{} is freely distributable.  It is written in a superset of Pascal
called WEB and can be compiled either in Pascal or (by using a
conversion program that comes with the @TeX{} distribution) in C.
(@xref{TeX Mode, ,@TeX{} Mode, emacs, The GNU Emacs Manual}, for information
about @TeX{}.)@refill

@TeX{} is very powerful and has a great many features.  Because a
Texinfo file must be able to present information both on a
character-only terminal in Info form and in a typeset book, the
formatting commands that Texinfo supports are necessarily limited.

To get a copy of @TeX{}, see
@ref{Obtaining TeX, , How to Obtain @TeX{}}.


@node Formatting Commands
@section @@-commands
@cindex @@-commands
@cindex Formatting commands

In a Texinfo file, the commands that tell @TeX{} how to typeset the
printed manual and tell @code{makeinfo} and
@code{texinfo-format-buffer} how to create an Info file are preceded
by @samp{@@}; they are called @dfn{@@-commands}.  For example,
@code{@@node} is the command to indicate a node and @code{@@chapter}
is the command to indicate the start of a chapter.@refill

@quotation Note
Almost all @@ command names are entirely lower case.
@end quotation

The Texinfo @@-commands are a strictly limited set of constructs.  The
strict limits make it possible for Texinfo files to be understood both
by @TeX{} and by the code that converts them into Info files.  You can
display Info files on any terminal that displays alphabetic and
numeric characters.  Similarly, you can print the output generated by
@TeX{} on a wide variety of printers.@refill

Depending on what they do or what arguments@footnote{The word
@dfn{argument} comes from the way it is used in mathematics and does not
refer to a dispute between two people; it refers to the information
presented to the command.  According to the @cite{Oxford English
Dictionary}, the word derives from the Latin for @dfn{to make clear,
prove}; thus it came to mean `the evidence offered as proof', which is
to say, `the information offered', which led to its mathematical
meaning.  In its other thread of derivation, the word came to mean `to
assert in a manner against which others may make counter assertions',
which led to the meaning of `argument' as a dispute.} they take, you
need to write @@-commands on lines of their own or as part of
sentences:

@itemize @bullet
@item
Write a command such as @code{@@quotation} at the beginning of a line as
the only text on the line.  (@code{@@quotation} begins an indented
environment.)

@item
Write a command such as @code{@@chapter} at the beginning of a line
followed by the command's arguments, in this case the chapter title, on
the rest of the line.  (@code{@@chapter} creates chapter titles.)@refill

@item
Write a command such as @code{@@dots@{@}} wherever you wish but usually
within a sentence. (@code{@@dots@{@}} creates an ellipsis @dots{})@refill

@item
Write a command such as @code{@@code@{@var{sample-code}@}} wherever you
wish (but usually within a sentence) with its argument,
@var{sample-code} in this example, between the braces.  (@code{@@code}
marks text as being code.)@refill

@item
Write a command such as @code{@@example} on a line of its own; write the
body-text on following lines; and write the matching @code{@@end}
command, @code{@@end example} in this case, on a line of its own
after the body-text. (@code{@@example} @dots{} @code{@@end example}
indents and typesets body-text as an example.)  It's usually ok to
indent environment commands like this, but in complicated and
hard-to-define circumstances the extra spaces cause extra space to
appear in the output, so beware.
@end itemize

@noindent
@cindex Braces, when to use
As a general rule, a command requires braces if it mingles among other
text; but it does not need braces if it starts a line of its own.  The
non-alphabetic commands, such as @code{@@:}, are exceptions to the rule;
they do not need braces.@refill

As you gain experience with Texinfo, you will rapidly learn how to
write the different commands: the different ways to write commands
actually make it easier to write and read Texinfo files than if all
commands followed exactly the same syntax.  @xref{Command Syntax, ,
@@-Command Syntax}, for all the details.


@node Conventions
@section General Syntactic Conventions
@cindex General syntactic conventions
@cindex Syntactic conventions
@cindex Conventions, syntactic
@cindex Characters, basic input

This section describes the general conventions used in all Texinfo documents.

@itemize @bullet
@item
@cindex Source files, characters used
All printable ASCII characters except @samp{@@}, @samp{@{} and
@samp{@}} can appear in a Texinfo file and stand for themselves.
@samp{@@} is the escape character which introduces commands, while
@samp{@{} and @samp{@}} are used to surround arguments to certain
commands.  To put one of these special characters into the document, put
an @samp{@@} character in front of it, like this: @samp{@@@@},
@samp{@@@{}, and @samp{@@@}}.

@item
@cindex Paragraph separator
@cindex Blank lines, as paragraph separator
@cindex Newlines, as blank lines
Separate paragraphs with one or more blank lines.  Currently Texinfo
only recognizes newline characters as end of line, not the CRLF
sequence used on some systems; so a @dfn{blank line} means exactly two
consecutive newlines.  Sometimes blank lines are useful or convenient
in other cases as well; you can use the @code{@@noindent} to inhibit
paragraph indentation if required (@pxref{noindent,,@code{@@noindent}}).

@item
Texinfo supports the usual quotation marks used in English, and
quotation marks used in other languages, please see @ref{Inserting
Quotation Marks}.

@item
@cindex Multiple dashes in source
@cindex Dashes in source
@cindex Hyphens in source, two or three in a row
@cindex Em dash, producing
@cindex En dash, producing
Use three hyphens in a row, @samp{---}, to produce a long dash---like
this (called an @dfn{em dash}), used for punctuation in sentences.
Use two hyphens, @samp{--}, to produce a medium dash (called an
@dfn{en dash}), used primarily for numeric ranges, as in ``June
25--26''.  Use a single hyphen, @samp{-}, to produce a standard hyphen
used in compound words.  For display on the screen, Info reduces three
hyphens to two and two hyphens to one (not transitively!).  Of course,
any number of hyphens in the source remain as they are in literal
contexts, such as @code{@@code} and @code{@@example}.

@item
@cindex Tabs; don't use!
@strong{Caution:} Last, do not use tab characters in a Texinfo file
(except in verbatim modes)!  @TeX{} uses variable-width fonts, which
means that it is impractical at best to define a tab to work in all
circumstances.  Consequently, @TeX{} treats tabs like single spaces,
and that is not what they look like in the source.  Furthermore,
@code{makeinfo} does nothing special with tabs, and thus a tab
character in your input file will usually appear differently in the
output.

@noindent
To avoid this problem, Texinfo mode in GNU Emacs inserts
multiple spaces when you press the @key{TAB} key.  Also, you can run
@code{untabify} in Emacs to convert tabs in a region to multiple
spaces, or use the @code{unexpand} command from the shell.

@end itemize


@node Comments
@section Comments

@cindex Comments
@findex comment
@findex c @r{(comment)}

You can write comments in a Texinfo file that will not appear in
either the Info file or the printed manual by using the
@code{@@comment} command (which may be abbreviated to @code{@@c}).
Such comments are for the person who revises the Texinfo file.  All the
text on a line that follows either @code{@@comment} or @code{@@c} is a
comment; the rest of the line does not appear in either the Info file
or the printed manual.

Often, you can write the @code{@@comment} or @code{@@c} in the middle of
a line, and only the text that follows after the @code{@@comment} or
@code{@@c} command does not appear; but some commands, such as
@code{@@settitle} and @code{@@setfilename}, work on a whole line.  You
cannot use @code{@@comment} or @code{@@c} in a line beginning with such
a command.

@cindex Ignored text
@cindex Unprocessed text
@findex ignore
You can write long stretches of text that will not appear in either
the Info file or the printed manual by using the @code{@@ignore} and
@code{@@end ignore} commands.  Write each of these commands on a line
of its own, starting each command at the beginning of the line.  Text
between these two commands does not appear in the processed output.
You can use @code{@@ignore} and @code{@@end ignore} for writing
comments.

Text enclosed by @code{@@ignore} or by failing @code{@@ifset} or
@code{@@ifclear} conditions is ignored in the sense that it will not
contribute to the formatted output.  However, @TeX{} and makeinfo must
still parse the ignored text, in order to understand when to @emph{stop}
ignoring text from the source file; that means that you may still get
error messages if you have invalid Texinfo commands within ignored text.


@node Minimum
@section What a Texinfo File Must Have
@cindex Minimal Texinfo file (requirements)
@cindex Must have in Texinfo file
@cindex Required in Texinfo file
@cindex Texinfo file minimum

By convention, the name of a Texinfo file ends with (in order of
preference) one of the extensions @file{.texinfo}, @file{.texi},
@file{.txi}, or @file{.tex}.  The longer extensions are preferred since
they describe more clearly to a human reader the nature of the file.
The shorter extensions are for operating systems that cannot handle long
file names.

In order to be made into a printed manual and an Info file, a Texinfo
file @strong{must} begin with lines like this:

@example
@group
\input texinfo
@@setfilename @var{info-file-name}
@@settitle @var{name-of-manual}
@end group
@end example

@noindent
The contents of the file follow this beginning, and then you
@strong{must} end a Texinfo file with a line like this:

@example
@@bye
@end example

@findex \input @r{(raw @TeX{} startup)}
@noindent
Here's an explanation:

@itemize @bullet
@item
The @samp{\input texinfo} line tells @TeX{} to use the
@file{texinfo.tex} file, which tells @TeX{} how to translate the Texinfo
@@-commands into @TeX{} typesetting commands.  (Note the use of the
backslash, @samp{\}; this is correct for @TeX{}.)

@item
The @code{@@setfilename} line provides a name for the Info file and
tells @TeX{} to open auxiliary files.  @strong{All text before
@code{@@setfilename} is ignored!}

@item
The @code{@@settitle} line specifies a title for the page headers (or
footers) of the printed manual, and the default document description for
the @samp{<head>} in HTML format.  Strictly speaking, @code{@@settitle}
is optional---if you don't mind your document being titled `Untitled'.

@item
The @code{@@bye} line at the end of the file on a line of its own tells
the formatters that the file is ended and to stop formatting.

@end itemize

Typically, you will not use quite such a spare format, but will include
mode setting and start-of-header and end-of-header lines at the
beginning of a Texinfo file, like this:

@example
@group
\input texinfo   @@c -*-texinfo-*-
@@c %**start of header
@@setfilename @var{info-file-name}
@@settitle @var{name-of-manual}
@@c %**end of header
@end group
@end example

@noindent
In the first line, @samp{-*-texinfo-*-} causes Emacs to switch into
Texinfo mode when you edit the file.

The @code{@@c} lines which surround the @code{@@setfilename} and
@code{@@settitle} lines are optional, but you need them in order to
run @TeX{} or Info on just part of the file.  (@xref{Start of Header}.)

Furthermore, you will usually provide a Texinfo file with a title page,
indices, and the like, all of which are explained in this manual.  But
the minimum, which can be useful for short documents, is just the three
lines at the beginning and the one line at the end.


@node Six Parts
@section Six Parts of a Texinfo File

Generally, a Texinfo file contains more than the minimal beginning and
end described in the previous section---it usually contains the six
parts listed below.  These are described fully in the following sections.

@table @r
@item 1. Header
The @dfn{Header} names the file, tells @TeX{} which definitions file to
use, and other such housekeeping tasks.

@item 2. Summary and Copyright
The @dfn{Summary and Copyright} segment describes the document and
contains the copyright notice and copying permissions.  This is done
with the @code{@@copying} command.

@item 3. Title and Copyright
The @dfn{Title and Copyright} segment contains the title and copyright
pages for the printed manual.  The segment must be enclosed between
@code{@@titlepage} and @code{@@end titlepage} commands.  The title and
copyright page appear only in the printed manual.

@item 4. `Top' Node and Master Menu
The `Top' node starts off the online output; it does not appear in the
printed manual.  We recommend including the copying permissions here as
well as the segments above.  And it contains at least a top-level menu
listing the chapters, and possibly a @dfn{Master Menu} listing all the
nodes in the entire document.

@item 5. Body
The @dfn{Body} of the document is typically structured like a
traditional book or encyclopedia, but it may be free form.

@item 6. End
The @dfn{End} segment may contain commands for printing indices, and
closes with the @code{@@bye} command on a line of its own.
@end table


@node Short Sample
@section A Short Sample Texinfo File
@cindex Sample Texinfo file, with comments

Here is a very short but complete Texinfo file, in the six conventional
parts enumerated in the previous section, so you can see how Texinfo
source appears in practice.  The first three parts of the file, from
@samp{\input texinfo} through to @samp{@@end titlepage}, look more
intimidating than they are: most of the material is standard
boilerplate; when writing a manual, you simply change the names as
appropriate.

@xref{Beginning a File}, for full documentation on the commands listed
here.  @xref{GNU Sample Texts}, for the full texts to be used in GNU
manuals.

In the following, the sample text is @emph{indented}; comments on it are
not.  The complete file, without interspersed comments, is shown in
@ref{Short Sample Texinfo File}.

@subheading Part 1: Header

@noindent
The header does not appear in either the Info file or the
printed output.  It sets various parameters, including the
name of the Info file and the title used in the header.

@example
@group
\input texinfo   @@c -*-texinfo-*-
@@c %**start of header
@@setfilename sample.info
@@settitle Sample Manual 1.0
@@c %**end of header
@end group
@end example

@subheading Part 2: Summary Description and Copyright

@noindent
A real manual includes more text here, according to the license under
which it is distributed.  @xref{GNU Sample Texts}.

@example
@group
@@copying
This is a short example of a complete Texinfo file, version 1.0.

Copyright @@copyright@{@} 2005 Free Software Foundation, Inc.
@@end copying
@end group
@end example

@subheading Part 3: Titlepage, Contents, Copyright

@noindent
The titlepage segment does not appear in the online output, only in the
printed manual.  We use the @code{@@insertcopying} command to
include the permission text from the previous section, instead of
writing it out again; it is output on the back of the title page.  The
@code{@@contents} command generates a table of contents.

@example
@group
@@titlepage
@@title Sample Title
@end group

@group
@@c The following two commands start the copyright page.
@@page
@@vskip 0pt plus 1filll
@@insertcopying
@@end titlepage
@end group

@@c Output the table of contents at the beginning.
@@contents
@end example

@subheading Part 4: `Top' Node and Master Menu

@noindent
The `Top' node contains the master menu for the Info file.  Since the
printed manual uses a table of contents rather than a menu, it
excludes the `Top' node.  We repeat the short description from the
beginning of the @samp{@@copying} text, but there's no need to repeat
the copyright information, so we don't use @samp{@@insertcopying} here.
The @samp{@@top} command itself helps @command{makeinfo} determine the
relationships between nodes.

@example
@@ifnottex
@@node Top
@@top Short Sample

This is a short sample Texinfo file.
@@end ifnottex

@group
@@menu
* First Chapter::    The first chapter is the
                       only chapter in this sample.
* Index::            Complete index.
@@end menu
@end group
@end example


@subheading Part 5: The Body of the Document

@noindent
The body segment contains all the text of the document, but not the
indices or table of contents.  This example illustrates a node and a
chapter containing an enumerated list.

@example
@group
@@node First Chapter
@@chapter First Chapter

@@cindex chapter, first
@end group

@group
This is the first chapter.
@@cindex index entry, another
@end group

@group
Here is a numbered list.

@@enumerate
@@item
This is the first item.

@@item
This is the second item.
@@end enumerate
@end group
@end example


@subheading Part 6: The End of the Document

@noindent
The end segment contains commands for generating an index in a node and
unnumbered chapter of its own, and the @code{@@bye} command that marks
the end of the document.

@example
@group
@@node Index
@@unnumbered Index
@end group

@group
@@printindex cp

@@bye
@end group
@end example


@subheading Some Results

Here is what the contents of the first chapter of the sample look like:

@sp 1
@need 700
@quotation
This is the first chapter.

Here is a numbered list.

@enumerate
@item
This is the first item.

@item
This is the second item.
@end enumerate
@end quotation


@node History
@section History

@cindex Stallman, Richard M.
@cindex Chassell, Robert J.
@cindex Fox, Brian
@cindex Berry, Karl
Richard M. Stallman invented the Texinfo format, wrote the initial
processors, and created Edition 1.0 of this manual.  Robert@tie{}J.
Chassell greatly revised and extended the manual, starting with
Edition 1.1.  Brian Fox was responsible for the standalone Texinfo
distribution until version 3.8, and wrote the standalone
@command{makeinfo} and @command{info} programs.  Karl Berry has
continued maintenance since Texinfo 3.8 (manual edition 2.22).

@cindex Pinard, Fran@,{c}ois
@cindex Zuhn, David D.
@cindex Weisshaus, Melissa
@cindex Zaretskii, Eli
@cindex Schwab, Andreas
@cindex Weinberg, Zack
Our thanks go out to all who helped improve this work, particularly the
indefatigable Eli Zaretskii and Andreas Schwab, who have provided
patches beyond counting.  Fran@,{c}ois Pinard and David@tie{}D. Zuhn,
tirelessly recorded and reported mistakes and obscurities.  Zack
Weinberg did the impossible by implementing the macro syntax in
@file{texinfo.tex}.  Special thanks go to Melissa Weisshaus for her
frequent reviews of nearly similar editions.  Dozens of others have
contributed patches and suggestions, they are gratefully acknowledged in
the @file{ChangeLog} file.  Our mistakes are our own.

@cindex Scribe
@cindex Reid, Brian
@cindex History of Texinfo
@cindex Texinfo history
A bit of history: in the 1970's at CMU, Brian Reid developed a program
and format named Scribe to mark up documents for printing.  It used the
@code{@@} character to introduce commands, as Texinfo does.  Much more
consequentially, it strove to describe document contents rather than
formatting, an idea wholeheartedly adopted by Texinfo.

@cindex Bolio
@cindex Bo@TeX{}
Meanwhile, people at MIT developed another, not too dissimilar format
called Bolio.  This then was converted to using @TeX{} as its typesetting
language: Bo@TeX{}.  The earliest Bo@TeX{} version seems to have been
0.02 on October 31, 1984.

Bo@TeX{} could only be used as a markup language for documents to be
printed, not for online documents.  Richard Stallman (RMS) worked on
both Bolio and Bo@TeX{}.  He also developed a nifty on-line help format
called Info, and then combined Bo@TeX{} and Info to create Texinfo, a
mark up language for text that is intended to be read both online and
as printed hard copy.


@node Texinfo Mode
@chapter Using Texinfo Mode
@cindex Texinfo mode
@cindex Mode, using Texinfo
@cindex GNU Emacs
@cindex Emacs

You may edit a Texinfo file with any text editor you choose.  A Texinfo
file is no different from any other ASCII file.  However, GNU Emacs
comes with a special mode, called Texinfo mode, that provides Emacs
commands and tools to help ease your work.

This chapter describes features of GNU Emacs' Texinfo mode but not any
features of the Texinfo formatting language.  So if you are reading this
manual straight through from the beginning, you may want to skim through
this chapter briefly and come back to it after reading succeeding
chapters which describe the Texinfo formatting language in detail.

@menu
* Texinfo Mode Overview::       How Texinfo mode can help you.
* Emacs Editing::               Texinfo mode adds to GNU Emacs' general
                                  purpose editing features.
* Inserting::                   How to insert frequently used @@-commands.
* Showing the Structure::       How to show the structure of a file.
* Updating Nodes and Menus::    How to update or create new nodes and menus.
* Info Formatting::             How to format for Info.
* Printing::                    How to format and print part or all of a file.
* Texinfo Mode Summary::        Summary of all the Texinfo mode commands.
@end menu

@node Texinfo Mode Overview
@section Texinfo Mode Overview

Texinfo mode provides special features for working with Texinfo files.
You can:

@itemize @bullet
@item
Insert frequently used @@-commands. @refill

@item
Automatically create @code{@@node} lines.

@item
Show the structure of a Texinfo source file.@refill

@item
Automatically create or update the `Next',
`Previous', and `Up' pointers of a node.

@item
Automatically create or update menus.@refill

@item
Automatically create a master menu.@refill

@item
Format a part or all of a file for Info.@refill

@item
Typeset and print part or all of a file.@refill
@end itemize

Perhaps the two most helpful features are those for inserting frequently
used @@-commands and for creating node pointers and menus.@refill

@node Emacs Editing
@section The Usual GNU Emacs Editing Commands

In most cases, the usual Text mode commands work the same in Texinfo
mode as they do in Text mode.  Texinfo mode adds new editing commands
and tools to GNU Emacs' general purpose editing features.  The major
difference concerns filling.  In Texinfo mode, the paragraph
separation variable and syntax table are redefined so that Texinfo
commands that should be on lines of their own are not inadvertently
included in paragraphs.  Thus, the @kbd{M-q} (@code{fill-paragraph})
command will refill a paragraph but not mix an indexing command on a
line adjacent to it into the paragraph.@refill

In addition, Texinfo mode sets the @code{page-delimiter} variable to
the value of @code{texinfo-chapter-level-regexp}; by default, this is
a regular expression matching the commands for chapters and their
equivalents, such as appendices.  With this value for the page
delimiter, you can jump from chapter title to chapter title with the
@kbd{C-x ]} (@code{forward-page}) and @kbd{C-x [}
(@code{backward-page}) commands and narrow to a chapter with the
@kbd{C-x n p} (@code{narrow-to-page}) command.  (@xref{Pages, , ,emacs,
The GNU Emacs Manual}, for details about the page commands.)@refill

You may name a Texinfo file however you wish, but the convention is to
end a Texinfo file name with one of the extensions
@file{.texinfo}, @file{.texi}, @file{.txi}, or @file{.tex}.  A longer
extension is preferred, since it is explicit, but a shorter extension
may be necessary for operating systems that limit the length of file
names.  GNU Emacs automatically enters Texinfo mode when you visit a
file with a @file{.texinfo}, @file{.texi} or @file{.txi}
extension.  Also, Emacs switches to Texinfo mode
when you visit a
file that has @samp{-*-texinfo-*-} in its first line.  If ever you are
in another mode and wish to switch to Texinfo mode, type @code{M-x
texinfo-mode}.@refill

Like all other Emacs features, you can customize or enhance Texinfo
mode as you wish.  In particular, the keybindings are very easy to
change.  The keybindings described here are the default or standard
ones.@refill

@node Inserting
@comment  node-name,  next,  previous,  up
@section Inserting Frequently Used Commands
@cindex Inserting frequently used commands
@cindex Frequently used commands, inserting
@cindex Commands, inserting them

Texinfo mode provides commands to insert various frequently used
@@-commands into the buffer.  You can use these commands to save
keystrokes.@refill

The insert commands are invoked by typing @kbd{C-c} twice and then the
first letter of the @@-command:@refill

@table @kbd
@item  C-c C-c c
@itemx M-x texinfo-insert-@@code
@findex texinfo-insert-@@code
Insert @code{@@code@{@}} and put the
cursor between the braces.@refill

@item  C-c C-c d
@itemx M-x texinfo-insert-@@dfn
@findex texinfo-insert-@@dfn
Insert @code{@@dfn@{@}} and put the
cursor between the braces.@refill

@item  C-c C-c e
@itemx M-x texinfo-insert-@@end
@findex texinfo-insert-@@end
Insert @code{@@end} and attempt to insert the correct following word,
such as @samp{example} or @samp{table}.  (This command does not handle
nested lists correctly, but inserts the word appropriate to the
immediately preceding list.)@refill

@item  C-c C-c i
@itemx M-x texinfo-insert-@@item
@findex texinfo-insert-@@item
Insert @code{@@item} and put the
cursor at the beginning of the next line.@refill

@item  C-c C-c k
@itemx M-x texinfo-insert-@@kbd
@findex texinfo-insert-@@kbd
Insert @code{@@kbd@{@}} and put the
cursor between the braces.@refill

@item  C-c C-c n
@itemx M-x texinfo-insert-@@node
@findex texinfo-insert-@@node
Insert @code{@@node} and a comment line
listing the sequence for the `Next',
`Previous', and `Up' nodes.
Leave point after the @code{@@node}.@refill

@item  C-c C-c o
@itemx M-x texinfo-insert-@@noindent
@findex texinfo-insert-@@noindent
Insert @code{@@noindent} and put the
cursor at the beginning of the next line.@refill

@item  C-c C-c s
@itemx M-x texinfo-insert-@@samp
@findex texinfo-insert-@@samp
Insert @code{@@samp@{@}} and put the
cursor between the braces.@refill

@item  C-c C-c t
@itemx M-x texinfo-insert-@@table
@findex texinfo-insert-@@table
Insert @code{@@table} followed by a @key{SPC}
and leave the cursor after the @key{SPC}.@refill

@item  C-c C-c v
@itemx M-x texinfo-insert-@@var
@findex texinfo-insert-@@var
Insert @code{@@var@{@}} and put the
cursor between the braces.@refill

@item  C-c C-c x
@itemx M-x texinfo-insert-@@example
@findex texinfo-insert-@@example
Insert @code{@@example} and put the
cursor at the beginning of the next line.@refill

@c M-@{  was the binding for texinfo-insert-braces;
@c in Emacs 19, backward-paragraph will take this binding.
@item C-c C-c @{
@itemx M-x texinfo-insert-braces
@findex texinfo-insert-braces
Insert @code{@{@}} and put the cursor between the braces.@refill

@item C-c @}
@itemx C-c  ]
@itemx M-x up-list
@findex up-list
Move from between a pair of braces forward past the closing brace.
Typing @kbd{C-c ]} is easier than typing @kbd{C-c @}}, which
is, however, more mnemonic; hence the two keybindings.  (Also, you can
move out from between braces by typing @kbd{C-f}.)@refill
@end table

To put a command such as @w{@code{@@code@{@dots{}@}}} around an
@emph{existing} word, position the cursor in front of the word and type
@kbd{C-u 1 C-c C-c c}.  This makes it easy to edit existing plain text.
The value of the prefix argument tells Emacs how many words following
point to include between braces---@samp{1} for one word, @samp{2} for
two words, and so on.  Use a negative argument to enclose the previous
word or words.  If you do not specify a prefix argument, Emacs inserts
the @@-command string and positions the cursor between the braces.  This
feature works only for those @@-commands that operate on a word or words
within one line, such as @code{@@kbd} and @code{@@var}.@refill

This set of insert commands was created after analyzing the frequency
with which different @@-commands are used in the @cite{GNU Emacs
Manual} and the @cite{GDB Manual}.  If you wish to add your own insert
commands, you can bind a keyboard macro to a key, use abbreviations,
or extend the code in @file{texinfo.el}.@refill

@findex texinfo-start-menu-description
@cindex Menu description, start
@cindex Description for menu, start
@kbd{C-c C-c C-d} (@code{texinfo-start-menu-description}) is an insert
command that works differently from the other insert commands.  It
inserts a node's section or chapter title in the space for the
description in a menu entry line.  (A menu entry has three parts, the
entry name, the node name, and the description.  Only the node name is
required, but a description helps explain what the node is about.
@xref{Menu Parts, , The Parts of a Menu}.)@refill

To use @code{texinfo-start-menu-description}, position point in a menu
entry line and type @kbd{C-c C-c C-d}.  The command looks for and copies
the title that goes with the node name, and inserts the title as a
description; it positions point at beginning of the inserted text so you
can edit it.  The function does not insert the title if the menu entry
line already contains a description.@refill

This command is only an aid to writing descriptions; it does not do the
whole job.  You must edit the inserted text since a title tends to use
the same words as a node name but a useful description uses different
words.@refill

@node Showing the Structure
@comment  node-name,  next,  previous,  up
@section Showing the Section Structure of a File
@cindex Showing the section structure of a file
@cindex Section structure of a file, showing it
@cindex Structure of a file, showing it
@cindex Outline of file structure, showing it
@cindex Contents-like outline of file structure
@cindex File section structure, showing it
@cindex Texinfo file section structure, showing it

You can show the section structure of a Texinfo file by using the
@kbd{C-c C-s} command (@code{texinfo-show-structure}).  This command
shows the section structure of a Texinfo file by listing the lines
that begin with the @@-commands for @code{@@chapter},
@code{@@section}, and the like.  It constructs what amounts
to a table of contents.  These lines are displayed in another buffer
called the @samp{*Occur*} buffer.  In that buffer, you can position
the cursor over one of the lines and use the @kbd{C-c C-c} command
(@code{occur-mode-goto-occurrence}), to jump to the corresponding spot
in the Texinfo file.@refill

@table @kbd
@item  C-c C-s
@itemx M-x texinfo-show-structure
@findex texinfo-show-structure
Show the @code{@@chapter}, @code{@@section}, and such lines of a
Texinfo file.@refill

@item  C-c C-c
@itemx M-x occur-mode-goto-occurrence
@findex occur-mode-goto-occurrence
Go to the line in the Texinfo file corresponding to the line under the
cursor in the @file{*Occur*} buffer.@refill
@end table

If you call @code{texinfo-show-structure} with a prefix argument by
typing @w{@kbd{C-u C-c C-s}}, it will list not only those lines with the
@@-commands for @code{@@chapter}, @code{@@section}, and the like, but
also the @code{@@node} lines.  You can use @code{texinfo-show-structure}
with a prefix argument to check whether the `Next', `Previous', and `Up'
pointers of an @code{@@node} line are correct.

Often, when you are working on a manual, you will be interested only
in the structure of the current chapter.  In this case, you can mark
off the region of the buffer that you are interested in by using the
@kbd{C-x n n} (@code{narrow-to-region}) command and
@code{texinfo-show-structure} will work on only that region.  To see
the whole buffer again, use @w{@kbd{C-x n w}} (@code{widen}).
(@xref{Narrowing, , , emacs, The GNU Emacs Manual}, for more
information about the narrowing commands.)@refill

@vindex page-delimiter
@cindex Page delimiter in Texinfo mode
In addition to providing the @code{texinfo-show-structure} command,
Texinfo mode sets the value of the page delimiter variable to match
the chapter-level @@-commands.  This enables you to use the @kbd{C-x
]} (@code{forward-page}) and @kbd{C-x [} (@code{backward-page})
commands to move forward and backward by chapter, and to use the
@kbd{C-x n p} (@code{narrow-to-page}) command to narrow to a chapter.
@xref{Pages, , , emacs, The GNU Emacs Manual}, for more information
about the page commands.@refill

@node Updating Nodes and Menus
@comment  node-name,  next,  previous,  up
@section Updating Nodes and Menus
@cindex Updating nodes and menus
@cindex Create nodes, menus automatically
@cindex Insert nodes, menus automatically
@cindex Automatically insert nodes, menus

Texinfo mode provides commands for automatically creating or updating
menus and node pointers.  The commands are called ``update'' commands
because their most frequent use is for updating a Texinfo file after you
have worked on it; but you can use them to insert the `Next',
`Previous', and `Up' pointers into an @code{@@node} line that has none
and to create menus in a file that has none.

If you do not use the updating commands, you need to write menus and
node pointers by hand, which is a tedious task.@refill

@menu
* Updating Commands::           Five major updating commands.
* Updating Requirements::       How to structure a Texinfo file for
                                  using the updating command.
* Other Updating Commands::     How to indent descriptions, insert
                                  missing nodes lines, and update
                                  nodes in sequence.
@end menu

@node Updating Commands
@subsection The Updating Commands

You can use the updating commands to:@refill

@itemize @bullet
@item
insert or update the `Next', `Previous', and `Up' pointers of a
node,@refill

@item
insert or update the menu for a section, and@refill

@item
create a master menu for a Texinfo source file.@refill
@end itemize

You can also use the commands to update all the nodes and menus in a
region or in a whole Texinfo file.@refill

The updating commands work only with conventional Texinfo files, which
are structured hierarchically like books.  In such files, a structuring
command line must follow closely after each @code{@@node} line, except
for the `Top' @code{@@node} line.  (A @dfn{structuring command line} is
a line beginning with @code{@@chapter}, @code{@@section}, or other
similar command.)

You can write the structuring command line on the line that follows
immediately after an @code{@@node} line or else on the line that
follows after a single @code{@@comment} line or a single
@code{@@ifinfo} line.  You cannot interpose more than one line between
the @code{@@node} line and the structuring command line; and you may
interpose only an @code{@@comment} line or an @code{@@ifinfo} line.

Commands which work on a whole buffer require that the `Top' node be
followed by a node with an @code{@@chapter} or equivalent-level command.
The menu updating commands will not create a main or master menu for a
Texinfo file that has only @code{@@chapter}-level nodes!  The menu
updating commands only create menus @emph{within} nodes for lower level
nodes.  To create a menu of chapters, you must provide a `Top'
node.

The menu updating commands remove menu entries that refer to other Info
files since they do not refer to nodes within the current buffer.  This
is a deficiency.  Rather than use menu entries, you can use cross
references to refer to other Info files.  None of the updating commands
affect cross references.@refill

Texinfo mode has five updating commands that are used most often: two
are for updating the node pointers or menu of a single node (or a
region); two are for updating every node pointer and menu in a file;
and one, the @code{texinfo-master-menu} command, is for creating a
master menu for a complete file, and optionally, for updating every
node and menu in the whole Texinfo file.@refill

The @code{texinfo-master-menu} command is the primary command:@refill

@table @kbd
@item C-c C-u m
@itemx M-x texinfo-master-menu
@findex texinfo-master-menu
Create or update a master menu that includes all the other menus
(incorporating the descriptions from pre-existing menus, if
any).@refill

With an argument (prefix argument, @kbd{C-u,} if interactive), first create or
update all the nodes and all the regular menus in the buffer before
constructing the master menu.  (@xref{The Top Node, , The Top Node and
Master Menu}, for more about a master menu.)@refill

For @code{texinfo-master-menu} to work, the Texinfo file must have a
`Top' node and at least one subsequent node.@refill

After extensively editing a Texinfo file, you can type the following:

@example
C-u M-x texinfo-master-menu
@exdent or
C-u C-c C-u m
@end example

@noindent
This updates all the nodes and menus completely and all at once.@refill
@end table

The other major updating commands do smaller jobs and are designed for
the person who updates nodes and menus as he or she writes a Texinfo
file.@refill

@need 1000
The commands are:@refill

@table @kbd
@item C-c C-u C-n
@itemx M-x texinfo-update-node
@findex texinfo-update-node
Insert the `Next', `Previous', and `Up' pointers for the node that point is
within (i.e., for the @code{@@node} line preceding point).  If the
@code{@@node} line has pre-existing `Next', `Previous', or `Up'
pointers in it, the old pointers are removed and new ones inserted.
With an argument (prefix argument, @kbd{C-u}, if interactive), this command
updates all @code{@@node} lines in the region (which is the text
between point and mark).@refill

@item C-c C-u C-m
@itemx M-x texinfo-make-menu
@findex texinfo-make-menu
Create or update the menu in the node that point is within.
With an argument (@kbd{C-u} as prefix argument, if
interactive), the command makes or updates menus for the
nodes which are either within or a part of the
region.@refill

Whenever @code{texinfo-make-menu} updates an existing menu, the
descriptions from that menu are incorporated into the new menu.  This
is done by copying descriptions from the existing menu to the entries
in the new menu that have the same node names.  If the node names are
different, the descriptions are not copied to the new menu.@refill

@item C-c C-u C-e
@itemx M-x texinfo-every-node-update
@findex texinfo-every-node-update
Insert or update the `Next', `Previous', and `Up' pointers for every
node in the buffer.@refill

@item C-c C-u C-a
@itemx M-x texinfo-all-menus-update
@findex texinfo-all-menus-update
Create or update all the menus in the buffer.  With an argument
(@kbd{C-u} as prefix argument, if interactive), first insert
or update all the node
pointers before working on the menus.@refill

If a master menu exists, the @code{texinfo-all-menus-update} command
updates it; but the command does not create a new master menu if none
already exists.  (Use the @code{texinfo-master-menu} command for
that.)@refill

When working on a document that does not merit a master menu, you can
type the following:

@example
C-u C-c C-u C-a
@exdent or
C-u M-x texinfo-all-menus-update
@end example

@noindent
This updates all the nodes and menus.@refill
@end table

The @code{texinfo-column-for-description} variable specifies the
column to which menu descriptions are indented.  By default, the value
is 32 although it can be useful to reduce it to as low as 24.  You
can set the variable via customization (@pxref{Changing an Option,,,
emacs, The GNU Emacs Manual}) or with the @kbd{M-x set-variable}
command (@pxref{Examining, , Examining and Setting Variables, emacs,
The GNU Emacs Manual}).

Also, the @code{texinfo-indent-menu-description} command may be used to
indent existing menu descriptions to a specified column.  Finally, if
you wish, you can use the @code{texinfo-insert-node-lines} command to
insert missing @code{@@node} lines into a file.  (@xref{Other Updating
Commands}, for more information.)@refill

@node Updating Requirements
@subsection Updating Requirements
@cindex Updating requirements
@cindex Requirements for updating commands

To use the updating commands, you must organize the Texinfo file
hierarchically with chapters, sections, subsections, and the like.
When you construct the hierarchy of the manual, do not `jump down'
more than one level at a time: you can follow the `Top' node with a
chapter, but not with a section; you can follow a chapter with a
section, but not with a subsection.  However, you may `jump up' any
number of levels at one time---for example, from a subsection to a
chapter.@refill

Each @code{@@node} line, with the exception of the line for the `Top'
node, must be followed by a line with a structuring command such as
@code{@@chapter}, @code{@@section}, or
@code{@@unnumberedsubsec}.@refill

Each @code{@@node} line/structuring-command line combination
must look either like this:

@example
@group
@@node     Comments,  Minimum, Conventions, Overview
@@comment  node-name, next,    previous,    up
@@section Comments
@end group
@end example

or like this (without the @code{@@comment} line):

@example
@group
@@node Comments, Minimum, Conventions, Overview
@@section Comments
@end group
@end example

or like this (without the explicit node pointers):

@example
@group
@@node Comments
@@section Comments
@end group
@end example

@noindent
In this example, `Comments' is the name of both the node and the
section.  The next node is called `Minimum' and the previous node is
called `Conventions'.  The `Comments' section is within the `Overview'
node, which is specified by the `Up' pointer.  (Instead of an
@code{@@comment} line, you may also write an @code{@@ifinfo} line.)

If a file has a `Top' node, it must be called @samp{top} or @samp{Top}
and be the first node in the file.

The menu updating commands create a menu of sections within a chapter,
a menu of subsections within a section, and so on.  This means that
you must have a `Top' node if you want a menu of chapters.@refill

Incidentally, the @code{makeinfo} command will create an Info file for a
hierarchically organized Texinfo file that lacks `Next', `Previous' and
`Up' pointers.  Thus, if you can be sure that your Texinfo file will be
formatted with @code{makeinfo}, you have no need for the update node
commands.  (@xref{Creating an Info File}, for more information about
@code{makeinfo}.)  However, both @code{makeinfo} and the
@code{texinfo-format-@dots{}} commands require that you insert menus in
the file.


@node Other Updating Commands
@subsection Other Updating Commands

In addition to the five major updating commands, Texinfo mode
possesses several less frequently used updating commands:@refill

@table @kbd
@item M-x texinfo-insert-node-lines
@findex texinfo-insert-node-lines
Insert @code{@@node} lines before the @code{@@chapter},
@code{@@section}, and other sectioning commands wherever they are
missing throughout a region in a Texinfo file.@refill

With an argument (@kbd{C-u} as prefix argument, if interactive), the
@code{texinfo-insert-node-lines} command not only inserts
@code{@@node} lines but also inserts the chapter or section titles as
the names of the corresponding nodes.  In addition, it inserts the
titles as node names in pre-existing @code{@@node} lines that lack
names.  Since node names should be more concise than section or
chapter titles, you must manually edit node names so inserted.@refill

For example, the following marks a whole buffer as a region and inserts
@code{@@node} lines and titles throughout:@refill

@example
C-x h C-u M-x texinfo-insert-node-lines
@end example

This command inserts titles as node names in @code{@@node} lines; the
@code{texinfo-start-menu-description} command (@pxref{Inserting,
Inserting Frequently Used Commands}) inserts titles as descriptions in
menu entries, a different action.  However, in both cases, you need to
edit the inserted text.

@item M-x texinfo-multiple-files-update
@findex texinfo-multiple-files-update @r{(in brief)}
Update nodes and menus in a document built from several separate files.
With @kbd{C-u} as a prefix argument, create and insert a master menu in
the outer file.  With a numeric prefix argument, such as @kbd{C-u 2}, first
update all the menus and all the `Next', `Previous', and `Up' pointers
of all the included files before creating and inserting a master menu in
the outer file.  The @code{texinfo-multiple-files-update} command is
described in the appendix on @code{@@include} files.
@xref{texinfo-multiple-files-update}.

@item M-x texinfo-indent-menu-description
@findex texinfo-indent-menu-description
Indent every description in the menu following point to the specified
column.  You can use this command to give yourself more space for
descriptions.  With an argument (@kbd{C-u} as prefix argument, if
interactive), the @code{texinfo-indent-menu-description} command indents
every description in every menu in the region.  However, this command
does not indent the second and subsequent lines of a multi-line
description.@refill

@item M-x texinfo-sequential-node-update
@findex texinfo-sequential-node-update
Insert the names of the nodes immediately following and preceding the
current node as the `Next' or `Previous' pointers regardless of those
nodes' hierarchical level.  This means that the `Next' node of a
subsection may well be the next chapter.  Sequentially ordered nodes are
useful for novels and other documents that you read through
sequentially.  (However, in Info, the @kbd{g *} command lets
you look through the file sequentially, so sequentially ordered nodes
are not strictly necessary.)  With an argument (prefix argument, if
interactive), the @code{texinfo-sequential-node-update} command
sequentially updates all the nodes in the region.@refill
@end table

@node Info Formatting
@comment  node-name,  next,  previous,  up
@section Formatting for Info
@cindex Formatting for Info
@cindex Running an Info formatter
@cindex Info formatting

Texinfo mode provides several commands for formatting part or all of a
Texinfo file for Info.  Often, when you are writing a document, you
want to format only part of a file---that is, a region.@refill

You can use either the @code{texinfo-format-region} or the
@code{makeinfo-region} command to format a region:@refill

@table @kbd
@findex texinfo-format-region
@item  C-c C-e C-r
@itemx M-x texinfo-format-region
@itemx C-c C-m C-r
@itemx M-x makeinfo-region
Format the current region for Info.@refill
@end table

You can use either the @code{texinfo-format-buffer} or the
@code{makeinfo-buffer} command to format a whole buffer:@refill

@table @kbd
@findex texinfo-format-buffer
@item  C-c C-e C-b
@itemx M-x texinfo-format-buffer
@itemx C-c C-m C-b
@itemx M-x makeinfo-buffer
Format the current buffer for Info.@refill
@end table

@need 1000
For example, after writing a Texinfo file, you can type the following:

@example
C-u C-c C-u m
@exdent or
C-u M-x texinfo-master-menu
@end example

@noindent
This updates all the nodes and menus.  Then type the following to create
an Info file:

@example
C-c C-m C-b
@exdent or
M-x makeinfo-buffer
@end example

For @TeX{} or the Info formatting commands to work, the file @emph{must}
include a line that has @code{@@setfilename} in its header.

@xref{Creating an Info File}, for details about Info formatting.@refill

@node Printing
@comment node-name,  next,  previous,  up
@section Printing
@cindex Formatting for printing
@cindex Printing a region or buffer
@cindex Region formatting and printing
@cindex Buffer formatting and printing
@cindex Part of file formatting and printing

Typesetting and printing a Texinfo file is a multi-step process in which
you first create a file for printing (called a DVI file), and then
print the file.  Optionally, you may also create indices.  To do this,
you must run the @code{texindex} command after first running the
@code{tex} typesetting command; and then you must run the @code{tex}
command again.  Or else run the @code{texi2dvi} command which
automatically creates indices as needed (@pxref{Format with texi2dvi}).

Often, when you are writing a document, you want to typeset and print
only part of a file to see what it will look like.  You can use the
@code{texinfo-tex-region} and related commands for this purpose.  Use
the @code{texinfo-tex-buffer} command to format all of a
buffer.@refill

@table @kbd
@item  C-c C-t C-b
@itemx M-x texinfo-tex-buffer
@findex texinfo-tex-buffer
Run @code{texi2dvi} on the buffer.  In addition to running @TeX{} on the
buffer, this command automatically creates or updates indices as
needed.@refill

@item  C-c C-t C-r
@itemx M-x texinfo-tex-region
@findex texinfo-tex-region
Run @TeX{} on the region.@refill

@item C-c C-t C-i
@itemx M-x texinfo-texindex
Run @code{texindex} to sort the indices of a Texinfo file formatted with
@code{texinfo-tex-region}.  The @code{texinfo-tex-region} command does
not run @code{texindex} automatically; it only runs the @code{tex}
typesetting command.  You must run the @code{texinfo-tex-region} command
a second time after sorting the raw index files with the @code{texindex}
command.  (Usually, you do not format an index when you format a region,
only when you format a buffer.  Now that the @code{texi2dvi} command
exists, there is little or no need for this command.)@refill

@item C-c C-t C-p
@itemx M-x texinfo-tex-print
@findex texinfo-tex-print
Print the file (or the part of the file) previously formatted with
@code{texinfo-tex-buffer} or @code{texinfo-tex-region}.@refill
@end table

For @code{texinfo-tex-region} or @code{texinfo-tex-buffer} to work, the
file @emph{must} start with a @samp{\input texinfo} line and must
include an @code{@@settitle} line.  The file must end with @code{@@bye}
on a line by itself.  (When you use @code{texinfo-tex-region}, you must
surround the @code{@@settitle} line with start-of-header and
end-of-header lines.)@refill

@xref{Hardcopy}, for a description of the other @TeX{} related
commands, such as @code{tex-show-print-queue}.@refill

@node Texinfo Mode Summary
@comment  node-name,  next,  previous,  up
@section Texinfo Mode Summary

In Texinfo mode, each set of commands has default keybindings that
begin with the same keys.  All the commands that are custom-created
for Texinfo mode begin with @kbd{C-c}.  The keys are somewhat
mnemonic.@refill

@subheading Insert Commands

The insert commands are invoked by typing @kbd{C-c} twice and then the
first letter of the @@-command to be inserted.  (It might make more
sense mnemonically to use @kbd{C-c C-i}, for `custom insert', but
@kbd{C-c C-c} is quick to type.)@refill

@example
C-c C-c c       @r{Insert} @samp{@@code}.
C-c C-c d       @r{Insert} @samp{@@dfn}.
C-c C-c e       @r{Insert} @samp{@@end}.
C-c C-c i       @r{Insert} @samp{@@item}.
C-c C-c n       @r{Insert} @samp{@@node}.
C-c C-c s       @r{Insert} @samp{@@samp}.
C-c C-c v       @r{Insert} @samp{@@var}.
C-c @{       @r{Insert braces.}
C-c ]
C-c @}       @r{Move out of enclosing braces.}

@group
C-c C-c C-d     @r{Insert a node's section title}
               @r{in the space for the description}
               @r{in a menu entry line.}
@end group
@end example

@subheading Show Structure

The @code{texinfo-show-structure} command is often used within a
narrowed region.@refill

@example
C-c C-s         @r{List all the headings.}
@end example

@subheading The Master Update Command

The @code{texinfo-master-menu} command creates a master menu; and can
be used to update every node and menu in a file as well.@refill

@c Probably should use @tables in this section.
@example
@group
C-c C-u m
M-x texinfo-master-menu
               @r{Create or update a master menu.}
@end group

@group
C-u C-c C-u m   @r{With @kbd{C-u} as a prefix argument, first}
               @r{create or update all nodes and regular}
               @r{menus, and then create a master menu.}
@end group
@end example

@subheading Update Pointers

The update pointer commands are invoked by typing @kbd{C-c C-u} and
then either @kbd{C-n} for @code{texinfo-update-node} or @kbd{C-e} for
@code{texinfo-every-node-update}.@refill

@example
C-c C-u C-n     @r{Update a node.}
C-c C-u C-e     @r{Update every node in the buffer.}
@end example

@subheading Update Menus

Invoke the  update menu commands by typing @kbd{C-c C-u}
and then either @kbd{C-m} for @code{texinfo-make-menu} or
@kbd{C-a} for @code{texinfo-all-menus-update}.  To update
both nodes and menus at the same time, precede @kbd{C-c C-u
C-a} with @kbd{C-u}.@refill

@example
C-c C-u C-m     @r{Make or update a menu.}

@group
C-c C-u C-a     @r{Make or update all}
               @r{menus in a buffer.}
@end group

@group
C-u C-c C-u C-a @r{With @kbd{C-u} as a prefix argument,}
               @r{first create or update all nodes and}
               @r{then create or update all menus.}
@end group
@end example

@subheading Format for Info

The Info formatting commands that are written in Emacs Lisp are
invoked by typing @kbd{C-c C-e} and then either @kbd{C-r} for a region
or @kbd{C-b} for the whole buffer.@refill

The Info formatting commands that are written in C and based on the
@code{makeinfo} program are invoked by typing @kbd{C-c C-m} and then
either @kbd{C-r} for a region or @kbd{C-b} for the whole buffer.@refill

@need 800
@noindent
Use the @code{texinfo-format@dots{}} commands:

@example
@group
C-c C-e C-r     @r{Format the region.}
C-c C-e C-b     @r{Format the buffer.}
@end group
@end example

@need 750
@noindent
Use @code{makeinfo}:

@example
C-c C-m C-r     @r{Format the region.}
C-c C-m C-b     @r{Format the buffer.}
C-c C-m C-l     @r{Recenter the @code{makeinfo} output buffer.}
C-c C-m C-k     @r{Kill the @code{makeinfo} formatting job.}
@end example

@subheading Typeset and Print

The @TeX{} typesetting and printing commands are invoked by typing
@kbd{C-c C-t} and then another control command: @kbd{C-r} for
@code{texinfo-tex-region}, @kbd{C-b} for @code{texinfo-tex-buffer},
and so on.@refill

@example
C-c C-t C-r     @r{Run @TeX{} on the region.}
C-c C-t C-b     @r{Run} @code{texi2dvi} @r{on the buffer.}
C-c C-t C-i     @r{Run} @code{texindex}.
C-c C-t C-p     @r{Print the DVI file.}
C-c C-t C-q     @r{Show the print queue.}
C-c C-t C-d     @r{Delete a job from the print queue.}
C-c C-t C-k     @r{Kill the current @TeX{} formatting job.}
C-c C-t C-x     @r{Quit a currently stopped @TeX{} formatting job.}
C-c C-t C-l     @r{Recenter the output buffer.}
@end example

@subheading Other Updating Commands

The remaining updating commands do not have standard keybindings because
they are rarely used.

@example
@group
M-x texinfo-insert-node-lines
               @r{Insert missing @code{@@node} lines in region.}
               @r{With @kbd{C-u} as a prefix argument,}
               @r{use section titles as node names.}
@end group

@group
M-x texinfo-multiple-files-update
               @r{Update a multi-file document.}
               @r{With @kbd{C-u 2} as a prefix argument,}
               @r{create or update all nodes and menus}
               @r{in all included files first.}
@end group

@group
M-x texinfo-indent-menu-description
               @r{Indent descriptions.}
@end group

@group
M-x texinfo-sequential-node-update
               @r{Insert node pointers in strict sequence.}
@end group
@end example


@node Beginning a File
@chapter Beginning a Texinfo File
@cindex Beginning a Texinfo file
@cindex Texinfo file beginning
@cindex File beginning

Certain pieces of information must be provided at the beginning of a
Texinfo file, such as the name for the output file(s), the title of the
document, and the Top node.  A table of contents is also generally
produced here.

This chapter expands on the minimal complete Texinfo source file
previously given (@pxref{Six Parts}).  It describes the numerous
commands for handling the traditional frontmatter items in Texinfo.

@cindex Frontmatter, text in
Straight text outside of any command before the Top node should be
avoided.  Such text is treated differently in the different output
formats: visible in @TeX{} and HTML, by default not shown in Info
readers, and so on.

@menu
* Sample Beginning::            A sample beginning for a Texinfo file.
* Texinfo File Header::         The first lines.
* Document Permissions::        Ensuring your manual is free.
* Titlepage & Copyright Page::  Creating the title and copyright pages.
* Contents::                    How to create a table of contents.
* The Top Node::                Creating the `Top' node and master menu.
* Global Document Commands::    Affecting formatting throughout.
* Software Copying Permissions::  Ensure that you and others continue to
                                   have the right to use and share software.
@end menu


@node Sample Beginning
@section Sample Texinfo File Beginning

@cindex Example beginning of Texinfo file

The following sample shows what is needed.  The elements given here are
explained in more detail in the following sections.  Other commands are
often included at the beginning of Texinfo files, but the ones here are
the most critical.

@xref{GNU Sample Texts}, for the full texts to be used in GNU manuals.

@example
\input texinfo   @@c -*-texinfo-*-
@@c %**start of header
@@setfilename @var{infoname}.info
@@settitle @var{name-of-manual} @var{version}
@@c %**end of header

@@copying
This manual is for @var{program}, version @var{version}.

Copyright @@copyright@{@} @var{years} @var{copyright-owner}.

@group
@@quotation
Permission is granted to @dots{}
@@end quotation
@@end copying
@end group

@group
@@titlepage
@@title @var{name-of-manual-when-printed}
@@subtitle @var{subtitle-if-any}
@@subtitle @var{second-subtitle}
@@author @var{author}
@end group

@group
@@c  The following two commands
@@c  start the copyright page.
@@page
@@vskip 0pt plus 1filll
@@insertcopying
@end group

Published by @dots{}
@@end titlepage

@@c So the toc is printed at the start.
@@contents

@@ifnottex
@@node Top
@@top @var{title}

This manual is for @var{program}, version @var{version}.
@@end ifnottex

@group
@@menu
* First Chapter::    Getting started @dots{}
* Second Chapter::          @dots{}
 @dots{}
* Copying::          Your rights and freedoms.
@@end menu
@end group

@group
@@node First Chapter
@@chapter First Chapter

@@cindex first chapter
@@cindex chapter, first
@dots{}
@end group
@end example


@node Texinfo File Header
@section Texinfo File Header
@cindex Header for Texinfo files
@cindex Texinfo file header

Texinfo files start with at least three lines that provide Info and
@TeX{} with necessary information.  These are the @code{\input texinfo}
line, the @code{@@settitle} line, and the @code{@@setfilename} line.

Also, if you want to format just part of the Texinfo file, you must
write the @code{@@settitle} and @code{@@setfilename} lines between
start-of-header and end-of-header lines.  The start- and end-of-header
lines are optional, but they do no harm, so you might as well always
include them.

Any command that affects document formatting as a whole makes sense to
include in the header.  @code{@@synindex} (@pxref{synindex}), for
instance, is another command often included in the header.  @xref{GNU
Sample Texts}, for complete sample texts.

Thus, the beginning of a Texinfo file generally looks like this:

@example
@group
\input texinfo   @@c -*-texinfo-*-
@@c %**start of header
@@setfilename sample.info
@@settitle Sample Manual 1.0
@@c %**end of header
@end group
@end example

@menu
* First Line::                  The first line of a Texinfo file.
* Start of Header::             Formatting a region requires this.
* setfilename::                 Tell Info the name of the Info file.
* settitle::                    Create a title for the printed work.
* End of Header::               Formatting a region requires this.
@end menu


@node First Line
@subsection The First Line of a Texinfo File
@cindex First line of a Texinfo file
@cindex Beginning line of a Texinfo file
@cindex Header of a Texinfo file

Every Texinfo file that is to be the top-level input to @TeX{} must begin
with a line that looks like this:

@example
\input texinfo   @@c -*-texinfo-*-
@end example

@noindent
This line serves two functions:

@enumerate
@item
When the file is processed by @TeX{}, the @samp{\input texinfo} command
tells @TeX{} to load the macros needed for processing a Texinfo file.
These are in a file called @file{texinfo.tex}, which should have been
installed on your system along with either the @TeX{} or Texinfo
software.  @TeX{} uses the backslash, @samp{\}, to mark the beginning of
a command, exactly as Texinfo uses @samp{@@}.  The @file{texinfo.tex}
file causes the switch from @samp{\} to @samp{@@}; before the switch
occurs, @TeX{} requires @samp{\}, which is why it appears at the
beginning of the file.

@item
When the file is edited in GNU Emacs, the @samp{-*-texinfo-*-} mode
specification tells Emacs to use Texinfo mode.
@end enumerate


@node Start of Header
@subsection Start of Header
@cindex Start of header line

A start-of-header line is a Texinfo comment that looks like this:

@example
@@c %**start of header
@end example

Write the start-of-header line on the second line of a Texinfo file.
Follow the start-of-header line with @code{@@setfilename} and
@code{@@settitle} lines and, optionally, with other commands that
globally affect the document formatting, such as @code{@@synindex} or
@code{@@footnotestyle}; and then by an end-of-header line (@pxref{End of
Header}).

The start- and end-of-header lines allow you to format only part of a
Texinfo file for Info or printing.  @xref{texinfo-format commands}.

The odd string of characters, @samp{%**}, is to ensure that no other
comment is accidentally taken for a start-of-header line.  You can
change it if you wish by setting the @code{tex-start-of-header} and/or
@code{tex-end-of-header} Emacs variables.  @xref{Texinfo Mode Printing}.


@node setfilename
@subsection @code{@@setfilename}: Set the output file name
@findex setfilename
@cindex Texinfo requires @code{@@setfilename}

In order to serve as the primary input file for either @code{makeinfo}
or @TeX{}, a Texinfo file must contain a line that looks like this:

@example
@@setfilename @var{info-file-name}
@end example

Write the @code{@@setfilename} command at the beginning of a line and
follow it on the same line by the Info file name.  Do not write anything
else on the line; anything on the line after the command is considered
part of the file name, including what would otherwise be a
comment.

@cindex Ignored before @code{@@setfilename}
@cindex @samp{\input} source line ignored
The Info formatting commands ignore everything written before the
@code{@@setfilename} line, which is why the very first line of
the file (the @code{\input} line) does not show up in the output.

The @code{@@setfilename} line specifies the name of the output file to
be generated.  This name must be different from the name of the Texinfo
file.  There are two conventions for choosing the name: you can either
remove the extension (such as @samp{.texi}) entirely from the input file
name, or, preferably, replace it with the @samp{.info} extension.

@cindex Length of file names
@cindex File name collision
@cindex Info file name, choosing
Although an explicit @samp{.info} extension is preferable, some
operating systems cannot handle long file names.  You can run into a
problem even when the file name you specify is itself short enough.
This occurs because the Info formatters split a long Info file into
short indirect subfiles, and name them by appending @samp{-1},
@samp{-2}, @dots{}, @samp{-10}, @samp{-11}, and so on, to the original
file name.  (@xref{Tag and Split Files}.)  The subfile name
@file{texinfo.info-10}, for example, is too long for old systems with a
14-character limit on filenames; so the Info file name for this document
is @file{texinfo} rather than @file{texinfo.info}.  When @code{makeinfo}
is running on operating systems such as MS-DOS which impose severe
limits on file names, it may remove some characters from the original
file name to leave enough space for the subfile suffix, thus producing
files named @file{texin-10}, @file{gcc.i12}, etc.

When producing HTML output, @code{makeinfo} will replace any extension
with @samp{html}, or add @samp{.html} if the given name has no
extension.

@pindex texinfo.cnf
The @code{@@setfilename} line produces no output when you typeset a
manual with @TeX{}, but it is nevertheless essential: it opens the
index, cross-reference, and other auxiliary files used by Texinfo, and
also reads @file{texinfo.cnf} if that file is present on your system
(@pxref{Preparing for TeX,, Preparing for @TeX{}}).


@node settitle
@subsection @code{@@settitle}: Set the document title
@findex settitle

In order to be made into a printed manual, a Texinfo file must contain
a line that looks like this:

@example
@@settitle @var{title}
@end example

Write the @code{@@settitle} command at the beginning of a line and
follow it on the same line by the title.  This tells @TeX{} the title to
use in a header or footer.  Do not write anything else on the line;
anything on the line after the command is considered part of the title,
including what would otherwise be a comment.

The @code{@@settitle} command should precede everything that generates
actual output.  The best place for it is right after the
@code{@@setfilename} command (see the previous section).

@cindex <title> HTML tag
In the HTML file produced by @command{makeinfo}, @var{title} serves as
the document @samp{<title>}.  It also becomes the default document
description in the @samp{<head>} part (@pxref{documentdescription}).

The title in the @code{@@settitle} command does not affect the title as
it appears on the title page.  Thus, the two do not need not match
exactly.  A practice we recommend is to include the version or edition
number of the manual in the @code{@@settitle} title; on the title page,
the version number generally appears as a @code{@@subtitle} so it would
be omitted from the @code{@@title}.  @xref{titlepage}.

Conventionally, when @TeX{} formats a Texinfo file for double-sided
output, the title is printed in the left-hand (even-numbered) page
headings and the current chapter title is printed in the right-hand
(odd-numbered) page headings.  (@TeX{} learns the title of each chapter
from each @code{@@chapter} command.)  By default, no page footer is
printed.

Even if you are printing in a single-sided style, @TeX{} looks for an
@code{@@settitle} command line, in case you include the manual title
in the heading.

@TeX{} prints page headings only for that text that comes after the
@code{@@end titlepage} command in the Texinfo file, or that comes
after an @code{@@headings} command that turns on headings.
(@xref{headings on off, , The @code{@@headings} Command}, for more
information.)

You may, if you wish, create your own, customized headings and footings.
@xref{Headings}, for a detailed discussion of this.


@node End of Header
@subsection End of Header
@cindex End of header line

Follow the header lines with an @w{end-of-header} line, which is a
Texinfo comment that looks like this:

@example
@@c %**end of header
@end example

@xref{Start of Header}.


@node Document Permissions
@section Document Permissions
@cindex Document Permissions
@cindex Copying Permissions

The copyright notice and copying permissions for a document need to
appear in several places in the various Texinfo output formats.
Therefore, Texinfo provides a command (@code{@@copying}) to declare
this text once, and another command (@code{@@insertcopying}) to
insert the text at appropriate points.

@menu
* copying::                     Declare the document's copying permissions.
* insertcopying::               Where to insert the permissions.
@end menu


@node copying
@subsection @code{@@copying}: Declare Copying Permissions
@findex copying

The @code{@@copying} command should be given very early in the document;
the recommended location is right after the header material
(@pxref{Texinfo File Header}).  It conventionally consists of a sentence
or two about what the program is, identification of the documentation
itself, the legal copyright line, and the copying permissions.  Here is
a skeletal example:

@example
@@copying
This manual is for @var{program} (version @var{version}, updated
@var{date}), which @dots{}

Copyright @@copyright@{@} @var{years} @var{copyright-owner}.

@@quotation
Permission is granted to @dots{}
@@end quotation
@@end copying
@end example

The @code{@@quotation} has no legal significance; it's there to improve
readability in some contexts.

@xref{GNU Sample Texts}, for the full text to be used in GNU manuals.
@xref{GNU Free Documentation License}, for the license itself under
which GNU and other free manuals are distributed.  You need to include
the license as an appendix to your document.

The text of @code{@@copying} is output as a comment at the beginning of
Info, HTML, and XML output files.  It is @emph{not} output implicitly in
plain text or @TeX{}; it's up to you to use @code{@@insertcopying} to
emit the copying information.  See the next section for details.

@findex copyright
The @code{@@copyright@{@}} command generates a @samp{c} inside a circle
in output formats that support this (print and HTML).  In the other
formats (Info and plain text), it generates @samp{(C)}.  The copyright
notice itself has the following legally defined sequence:

@example
Copyright @copyright{} @var{years} @var{copyright-owner}.
@end example

@cindex Copyright word, always in English
The word `Copyright' must always be written in English, even if the
document is otherwise written in another language.  This is due to
international law.

@cindex Years, in copyright line
The list of years should include all years in which a version was
completed (even if it was released in a subsequent year).  Ranges are
not allowed; each year must be written out individually and in full,
separated by commas.

@cindex Copyright holder for FSF works
@cindex Holder of copyright for FSF works
@cindex Owner of copyright for FSF works
The copyright owner (or owners) is whoever holds legal copyright on the
work.  In the case of works assigned to the FSF, the owner is `Free
Software Foundation, Inc.'.

The copyright `line' may actually be split across multiple lines, both
in the source document and in the output.  This often happens for
documents with a long history, having many different years of
publication.  If you do use several lines, do not indent any of them
(or anything else in the @code{@@copying} block) in the source file.

@xref{Copyright Notices,,,maintain,GNU Maintenance Instructions}, for
additional information.


@node insertcopying
@subsection @code{@@insertcopying}: Include Permissions Text
@findex insertcopying
@cindex Copying text, including
@cindex Permissions text, including
@cindex Including permissions text

The @code{@@insertcopying} command is simply written on a line by
itself, like this:

@example
@@insertcopying
@end example

This inserts the text previously defined by @code{@@copying}.  To meet
legal requirements, it must be used on the copyright page in the printed
manual (@pxref{Copyright}).

The @code{@@copying} command itself causes the permissions text to
appear in an Info file @emph{before} the first node.  The text is also
copied into the beginning of each split Info output file, as is legally
necessary.  This location implies a human reading the manual using Info
does @emph{not} see this text (except when using the advanced Info
command @kbd{g *}), but this does not matter for legal purposes,
because the text is present.

Similarly, the @code{@@copying} text is automatically included at the
beginning of each HTML output file, as an HTML comment.  Again, this
text is not visible (unless the reader views the HTML source).

The permissions text defined by @code{@@copying} also appears
automatically at the beginning of the XML output file.


@node Titlepage & Copyright Page
@section Title and Copyright Pages

In hard copy output, the manual's name and author are usually printed on
a title page.  Copyright information is usually printed on the back of
the title page.

The title and copyright pages appear in the printed manual, but not in
the Info file.  Because of this, it is possible to use several slightly
obscure @TeX{} typesetting commands that cannot be used in an Info file.
In addition, this part of the beginning of a Texinfo file contains the
text of the copying permissions that appears in the printed manual.

@cindex Title page, for plain text
@cindex Copyright page, for plain text
You may wish to include titlepage-like information for plain text
output.  Simply place any such leading material between
@code{@@ifplaintext} and @code{@@end ifplaintext}; @command{makeinfo}
includes this when writing plain text (@samp{--no-headers}), along with
an @code{@@insertcopying}.

@menu
* titlepage::                   Create a title for the printed document.
* titlefont center sp::         The @code{@@titlefont}, @code{@@center},
                                 and @code{@@sp} commands.
* title subtitle author::       The @code{@@title}, @code{@@subtitle},
                                 and @code{@@author} commands.
* Copyright::                   How to write the copyright notice and
                                 include copying permissions.
* end titlepage::               Turn on page headings after the title and
                                 copyright pages.
* headings on off::             An option for turning headings on and off
                                 and double or single sided printing.
@end menu


@node titlepage
@subsection @code{@@titlepage}
@cindex Title page
@findex titlepage

Start the material for the title page and following copyright page
with @code{@@titlepage} on a line by itself and end it with
@code{@@end titlepage} on a line by itself.

The @code{@@end titlepage} command starts a new page and turns on page
numbering.  (@xref{Headings, , Page Headings}, for details about how to
generate page headings.)  All the material that you want to appear on
unnumbered pages should be put between the @code{@@titlepage} and
@code{@@end titlepage} commands.  You can force the table of contents to
appear there with the @code{@@setcontentsaftertitlepage} command
(@pxref{Contents}).

@findex page@r{, within @code{@@titlepage}}
By using the @code{@@page} command you can force a page break within the
region delineated by the @code{@@titlepage} and @code{@@end titlepage}
commands and thereby create more than one unnumbered page.  This is how
the copyright page is produced.  (The @code{@@titlepage} command might
perhaps have been better named the @code{@@titleandadditionalpages}
command, but that would have been rather long!)

When you write a manual about a computer program, you should write the
version of the program to which the manual applies on the title page.
If the manual changes more frequently than the program or is independent
of it, you should also include an edition number@footnote{We have found
that it is helpful to refer to versions of independent manuals as
`editions' and versions of programs as `versions'; otherwise, we find we
are liable to confuse each other in conversation by referring to both
the documentation and the software with the same words.} for the manual.
This helps readers keep track of which manual is for which version of
the program.  (The `Top' node should also contain this information; see
@ref{The Top Node}.)

Texinfo provides two main methods for creating a title page.  One method
uses the @code{@@titlefont}, @code{@@sp}, and @code{@@center} commands
to generate a title page in which the words on the page are
centered.

The second method uses the @code{@@title}, @code{@@subtitle}, and
@code{@@author} commands to create a title page with black rules under
the title and author lines and the subtitle text set flush to the
right hand side of the page.  With this method, you do not specify any
of the actual formatting of the title page.  You specify the text
you want, and Texinfo does the formatting.

You may use either method, or you may combine them; see the examples in
the sections below.

@findex shorttitlepage
@cindex Bastard title page
@cindex Title page, bastard
For extremely simple documents, and for the bastard title page in
traditional book frontmatter, Texinfo also provides a command
@code{@@shorttitlepage} which takes the rest of the line as the title.
The argument is typeset on a page by itself and followed by a blank
page.


@node titlefont center sp
@subsection @code{@@titlefont}, @code{@@center}, and @code{@@sp}
@findex titlefont
@findex center
@findex sp @r{(titlepage line spacing)}

You can use the @code{@@titlefont}, @code{@@sp}, and @code{@@center}
commands to create a title page for a printed document.  (This is the
first of the two methods for creating a title page in Texinfo.)

Use the @code{@@titlefont} command to select a large font suitable for
the title itself.  You can use @code{@@titlefont} more than once if you
have an especially long title.

For HTML output, each @code{@@titlefont} command produces an
@code{<h1>} heading, but the HTML document @code{<title>} is not
affected.  For that, you must put an @code{@@settitle} command before
the @code{@@titlefont} command (@pxref{settitle}).

@need 700
For example:

@example
@@titlefont@{Texinfo@}
@end example

Use the @code{@@center} command at the beginning of a line to center
the remaining text on that line.  Thus,

@example
@@center @@titlefont@{Texinfo@}
@end example

@noindent
centers the title, which in this example is ``Texinfo'' printed
in the title font.

Use the @code{@@sp} command to insert vertical space.  For example:

@example
@@sp 2
@end example

@noindent
This inserts two blank lines on the printed page.  (@xref{sp, ,
@code{@@sp}}, for more information about the @code{@@sp}
command.)

A template for this method looks like this:

@example
@group
@@titlepage
@@sp 10
@@center @@titlefont@{@var{name-of-manual-when-printed}@}
@@sp 2
@@center @var{subtitle-if-any}
@@sp 2
@@center @var{author}
@dots{}
@@end titlepage
@end group
@end example

The spacing of the example fits an 8.5 by 11 inch manual.

You can in fact use these commands anywhere, not just on a title page,
but since they are not logical markup commands, we don't recommend
them.

@node title subtitle author
@subsection @code{@@title}, @code{@@subtitle}, and @code{@@author}
@findex title
@findex subtitle
@findex author

You can use the @code{@@title}, @code{@@subtitle}, and @code{@@author}
commands to create a title page in which the vertical and horizontal
spacing is done for you automatically.  This contrasts with the method
described in the previous section, in which the @code{@@sp} command is
needed to adjust vertical spacing.

Write the @code{@@title}, @code{@@subtitle}, or @code{@@author}
commands at the beginning of a line followed by the title, subtitle,
or author.  These commands are only effective in @TeX{} output; it's
an error to use them anywhere except within @code{@@titlepage}.

The @code{@@title} command produces a line in which the title is set
flush to the left-hand side of the page in a larger than normal font.
The title is underlined with a black rule.  Only a single line is
allowed; the @code{@@*} command may not be used to break the title into
two lines.  To handle very long titles, you may find it profitable to
use both @code{@@title} and @code{@@titlefont}; see the final example in
this section.

The @code{@@subtitle} command sets subtitles in a normal-sized font
flush to the right-hand side of the page.

The @code{@@author} command sets the names of the author or authors in
a middle-sized font flush to the left-hand side of the page on a line
near the bottom of the title page.  The names are underlined with a
black rule that is thinner than the rule that underlines the title.
(The black rule only occurs if the @code{@@author} command line is
followed by an @code{@@page} command line.)

There are two ways to use the @code{@@author} command: you can write
the name or names on the remaining part of the line that starts with
an @code{@@author} command:

@example
@@author by Jane Smith and John Doe
@end example

@noindent
or you can write the names one above each other by using two (or more)
@code{@@author} commands:

@example
@group
@@author Jane Smith
@@author John Doe
@end group
@end example

@noindent
(Only the bottom name is underlined with a black rule.)

@need 950
A template for this method looks like this:

@example
@group
@@titlepage
@@title @var{name-of-manual-when-printed}
@@subtitle @var{subtitle-if-any}
@@subtitle @var{second-subtitle}
@@author @var{author}
@@page
@dots{}
@@end titlepage
@end group
@end example

You may also combine the @code{@@titlefont} method described in the
previous section and @code{@@title} method described in this one.  This
may be useful if you have a very long title.  Here is a real-life example:

@example
@group
@@titlepage
@@titlefont@{GNU Software@}
@@sp 1
@@title for MS-Windows and MS-DOS
@@subtitle Edition @@value@{e@} for Release @@value@{cde@}
@@author by Daniel Hagerty, Melissa Weisshaus
@@author and Eli Zaretskii
@end group
@end example

@noindent
(The use of @code{@@value} here is explained in @ref{value Example}.


@node Copyright
@subsection Copyright Page
@cindex Copyright page
@cindex Printed permissions
@cindex Permissions, printed

By international treaty, the copyright notice for a book must be either
on the title page or on the back of the title page.  When the copyright
notice is on the back of the title page, that page is customarily not
numbered.  Therefore, in Texinfo, the information on the copyright page
should be within @code{@@titlepage} and @code{@@end titlepage}
commands.

@findex vskip @r{@TeX{} vertical skip}
@findex filll @r{@TeX{} dimension}
Use the @code{@@page} command to cause a page break.  To push the
copyright notice and the other text on the copyright page towards the
bottom of the page, use the following incantation after @code{@@page}:

@example
@@vskip 0pt plus 1filll
@end example

@noindent
This is a @TeX{} command that is not supported by the Info formatting
commands.  The @code{@@vskip} command inserts whitespace.  The @samp{0pt
plus 1filll} means to put in zero points of mandatory whitespace, and as
much optional whitespace as needed to push the following text to the
bottom of the page.  Note the use of three @samp{l}s in the word
@samp{filll}; this is correct.

To insert the copyright text itself, write @code{@@insertcopying}
next (@pxref{Document Permissions}):

@example
@@insertcopying
@end example

Follow the copying text by the publisher, ISBN numbers, cover art
credits, and other such information.

Here is an example putting all this together:

@example
@@titlepage
@dots{}
@@page
@@vskip 0pt plus 1filll
@@insertcopying

Published by @dots{}

Cover art by @dots{}
@@end titlepage
@end example


@node end titlepage
@subsection Heading Generation
@findex end titlepage
@cindex Headings, page, begin to appear
@cindex Titlepage end starts headings
@cindex End titlepage starts headings

Like all @code{@@end} commands (@pxref{Quotations and Examples}), the @code{@@end titlepage} command
must be written at the beginning of a line by itself, with only one
space between the @code{@@end} and the @code{titlepage}.  It not only
marks the end of the title and copyright pages, but also causes @TeX{}
to start generating page headings and page numbers.

To repeat what is said elsewhere,  Texinfo has two standard page heading
formats, one for documents which are printed on one side of each sheet of paper
(single-sided printing), and the other for documents which are printed on both
sides of each sheet (double-sided printing).
You can specify these formats in different ways:

@itemize @bullet
@item
The conventional way is to write an @code{@@setchapternewpage} command
before the title page commands, and then have the @code{@@end
titlepage} command start generating page headings in the manner desired.
(@xref{setchapternewpage}.)

@item
Alternatively, you can use the @code{@@headings} command to prevent page
headings from being generated or to start them for either single or
double-sided printing.  (Write an @code{@@headings} command immediately
after the @code{@@end titlepage} command.  @xref{headings on off, , The
@code{@@headings} Command}, for more information.)@refill

@item
Or, you may specify your own page heading and footing format.
@xref{Headings, , Page Headings}, for detailed
information about page headings and footings.
@end itemize

Most documents are formatted with the standard single-sided or
double-sided format, using @code{@@setchapternewpage odd} for
double-sided printing and no @code{@@setchapternewpage} command for
single-sided printing.


@node headings on off
@subsection The @code{@@headings} Command
@findex headings

The @code{@@headings} command is rarely used.  It specifies what kind of
page headings and footings to print on each page.  Usually, this is
controlled by the @code{@@setchapternewpage} command.  You need the
@code{@@headings} command only if the @code{@@setchapternewpage} command
does not do what you want, or if you want to turn off predefined page
headings prior to defining your own.  Write an @code{@@headings} command
immediately after the @code{@@end titlepage} command.

You can use @code{@@headings} as follows:

@table @code
@item @@headings off
Turn off printing of page headings.

@item @@headings single
Turn on page headings appropriate for single-sided printing.

@item @@headings double
Turn on page headings appropriate for double-sided printing.  

@item @@headings singleafter
@itemx @@headings doubleafter
Turn on @code{single} or @code{double} headings, respectively, after the
current page is output.

@item @@headings on
Turn on page headings: @code{single} if @samp{@@setchapternewpage
on}, @code{double} otherwise.
@end table

For example, suppose you write @code{@@setchapternewpage off} before the
@code{@@titlepage} command to tell @TeX{} to start a new chapter on the
same page as the end of the last chapter.  This command also causes
@TeX{} to typeset page headers for single-sided printing.  To cause
@TeX{} to typeset for double sided printing, write @code{@@headings
double} after the @code{@@end titlepage} command.

You can stop @TeX{} from generating any page headings at all by
writing @code{@@headings off} on a line of its own immediately after the
line containing the @code{@@end titlepage} command, like this:

@example
@@end titlepage
@@headings off
@end example

@noindent
The @code{@@headings off} command overrides the @code{@@end titlepage}
command, which would otherwise cause @TeX{} to print page headings.

You can also specify your own style of page heading and footing.
@xref{Headings, , Page Headings}, for more information.


@node Contents
@section Generating a Table of Contents
@cindex Table of contents
@cindex Contents, Table of
@cindex Short table of contents
@findex contents
@findex summarycontents
@findex shortcontents

The @code{@@chapter}, @code{@@section}, and other structuring commands
(@pxref{Structuring}) supply the information to make up a
table of contents, but they do not cause an actual table to appear in
the manual.  To do this, you must use the @code{@@contents} and/or
@code{@@summarycontents} command(s).

@table @code
@item @@contents
Generates a table of contents in a printed manual, including all
chapters, sections, subsections, etc., as well as appendices and
unnumbered chapters.  Headings generated by @code{@@majorheading},
@code{@@chapheading}, and the other @code{@@@dots{}heading} commands
do not appear in the table of contents (@pxref{Structuring Command
Types}).

@item @@shortcontents
@itemx @@summarycontents
(@code{@@summarycontents} is a synonym for @code{@@shortcontents}.)

Generates a short or summary table of contents that lists only the
chapters, appendices, and unnumbered chapters.  Sections, subsections
and subsubsections are omitted.  Only a long manual needs a short
table of contents in addition to the full table of contents.

@end table

Both contents commands should be written on a line by themselves, and
are best placed near the beginning of the file, after the @code{@@end
titlepage} (@pxref{titlepage}).  The contents commands automatically
generate a chapter-like heading at the top of the first table of
contents page, so don't include any sectioning command such as
@code{@@unnumbered} before them.

Since an Info file uses menus instead of tables of contents, the Info
formatting commands ignore the contents commands.  But the contents are
included in plain text output (generated by @code{makeinfo
--no-headers}), unless @code{makeinfo} is writing its output to standard
output.

When @code{makeinfo} writes a short table of contents while producing
HTML output, the links in the short table of contents point to
corresponding entries in the full table of contents rather than the text
of the document. The links in the full table of contents point to the
main text of the document.

In the past, the contents commands were sometimes placed at the end of
the file, after any indices and just before the @code{@@bye}, but we
no longer recommend this.

@findex setcontentsaftertitlepage
@findex setshortcontentsaftertitlepage
@cindex Contents, after title page
@cindex Table of contents, after title page
However, since many existing Texinfo documents still do have the
@code{@@contents} at the end of the manual, if you are a user printing
a manual, you may wish to force the contents to be printed after the
title page.  You can do this by specifying
@code{@@setcontentsaftertitlepage} and/or
@code{@@setshortcontentsaftertitlepage}.  The first prints only the
main contents after the @code{@@end titlepage}; the second prints both
the short contents and the main contents.  In either case, any
subsequent @code{@@contents} or @code{@@shortcontents} is ignored
(unless, erroneously, no @code{@@end titlepage} is ever encountered).

You need to include the @code{@@set@dots{}contentsaftertitlepage}
commands early in the document (just after @code{@@setfilename}, for
example).  We recommend using @command{texi2dvi} (@pxref{Format with
texi2dvi}) to specify this without altering the source file at all.  For
example:
@example
texi2dvi --texinfo=@@setcontentsaftertitlepage foo.texi
@end example


@node The Top Node
@section The `Top' Node and Master Menu
@cindex Top node
@cindex Node, `Top'

The `Top' node is the node in which a reader enters an Info manual.
As such, it should begin with a brief description of the manual
(including the version number), and end with a master menu for the
whole manual.  Of course you should include any other general
information you feel a reader would find helpful.

@findex top
It is conventional and desirable to write an @code{@@top} sectioning
command line containing the title of the document immediately after
the @code{@@node Top} line (@pxref{makeinfo top command, , The
@code{@@top} Sectioning Command}).

The contents of the `Top' node should appear only in the online output;
none of it should appear in printed output, so enclose it between
@code{@@ifnottex} and @code{@@end ifnottex} commands.  (@TeX{} does not
print either an @code{@@node} line or a menu; they appear only in Info;
strictly speaking, you are not required to enclose these parts between
@code{@@ifnottex} and @code{@@end ifnottex}, but it is simplest to do
so.  @xref{Conditionals, , Conditionally Visible Text}.)

@menu
* Top Node Example::
* Master Menu Parts::
@end menu


@node Top Node Example
@subsection Top Node Example

@cindex Top node example

Here is an example of a Top node.

@example
@group
@@ifnottex
@@node Top
@@top Sample Title

@@insertcopying
@@end ifnottex
@end group

Additional general information.

@group
@@menu
* First Chapter::
* Second Chapter::
@dots{}
* Index::
@end group
@@end menu
@end example


@node Master Menu Parts
@subsection Parts of a Master Menu
@cindex Master menu
@cindex Menu, master
@cindex Parts of a master menu

A @dfn{master menu} is a detailed main menu listing all the nodes in a
file.

A master menu is enclosed in @code{@@menu} and @code{@@end menu}
commands and does not appear in the printed document.

Generally, a master menu is divided into parts.

@itemize @bullet
@item
The first part contains the major nodes in the Texinfo file: the nodes
for the chapters, chapter-like sections, and the appendices.

@item
The second part contains nodes for the indices.

@item
@findex detailmenu
@cindex Detailed menu
The third and subsequent parts contain a listing of the other, lower
level nodes, often ordered by chapter.  This way, rather than go
through an intermediary menu, an inquirer can go directly to a
particular node when searching for specific information.  These menu
items are not required; add them if you think they are a
convenience.  If you do use them, put @code{@@detailmenu} before the
first one, and @code{@@end detailmenu} after the last; otherwise,
@code{makeinfo} will get confused.
@end itemize

Each section in the menu can be introduced by a descriptive line.  So
long as the line does not begin with an asterisk, it will not be
treated as a menu entry.  (@xref{Writing a Menu}, for more
information.)

For example, the master menu for this manual looks like the following
(but has many more entries):

@example
@group
@@menu
* Copying Conditions::  Your rights.
* Overview::            Texinfo in brief.
@dots{}
@end group
@group
* Command and Variable Index::
* General Index::
@end group

@group
@@detailmenu
--- The Detailed Node Listing ---

Overview of Texinfo

* Reporting Bugs:: @dots{}
@dots{}
@end group

@group
Beginning a Texinfo File

* Sample Beginning:: @dots{}
@dots{}
@@end detailmenu
@@end menu
@end group
@end example


@node Global Document Commands
@section Global Document Commands
@cindex Global Document Commands

Besides the basic commands mentioned in the previous sections, here are
additional commands which affect the document as a whole.  They are
generally all given before the Top node, if they are given at all.

@menu
* documentdescription::         Document summary for the HTML output.
* setchapternewpage::           Start chapters on right-hand pages.
* paragraphindent::             Specify paragraph indentation.
* firstparagraphindent::        Suppress indentation of the first paragraph.
* exampleindent::               Specify environment indentation.
@end menu


@node documentdescription
@subsection @code{@@documentdescription}: Summary Text
@cindex Document description
@cindex Description of document
@cindex Summary of document
@cindex Abstract of document
@cindex <meta> HTML tag, and document description
@findex documentdescription

When producing HTML output for a document, @command{makeinfo} writes a
@samp{<meta>} element in the @samp{<head>} to give some idea of the
content of the document.  By default, this @dfn{description} is the title
of the document, taken from the @code{@@settitle} command
(@pxref{settitle}).  To change this, use the @code{@@documentdescription}
environment, as in:

@example
@@documentdescription
descriptive text.
@@end documentdescription
@end example

@noindent
This will produce the following output in the @samp{<head>} of the HTML:

@example
<meta name=description content="descriptive text.">
@end example

@code{@@documentdescription} must be specified before the first node of
the document.


@node setchapternewpage
@subsection @code{@@setchapternewpage}:
@cindex Starting chapters
@cindex Pages, starting odd
@findex setchapternewpage

In an officially bound book, text is usually printed on both sides of
the paper, chapters start on right-hand pages, and right-hand pages have
odd numbers.  But in short reports, text often is printed only on one
side of the paper.  Also in short reports, chapters sometimes do not
start on new pages, but are printed on the same page as the end of the
preceding chapter, after a small amount of vertical whitespace.

You can use the @code{@@setchapternewpage} command with various
arguments to specify how @TeX{} should start chapters and whether it
should format headers for printing on one or both sides of the paper
(single-sided or double-sided printing).

Write the @code{@@setchapternewpage} command at the beginning of a
line followed by its argument.

For example, you would write the following to cause each chapter to
start on a fresh odd-numbered page:

@example
@@setchapternewpage odd
@end example

You can specify one of three alternatives with the
@code{@@setchapternewpage} command:

@table @asis

@item @code{@@setchapternewpage off}
Cause @TeX{} to typeset a new chapter on the same page as the last
chapter, after skipping some vertical whitespace.  Also, cause @TeX{} to
format page headers for single-sided printing.

@item @code{@@setchapternewpage on}
Cause @TeX{} to start new chapters on new pages and to format page
headers for single-sided printing.  This is the form most often used for
short reports or personal printing. This is the default.

@item @code{@@setchapternewpage odd}
Cause @TeX{} to start new chapters on new, odd-numbered pages
(right-handed pages) and to typeset for double-sided printing.  This is
the form most often used for books and manuals.
@end table

Texinfo does not have an @code{@@setchapternewpage even} command,
because there is no printing tradition of starting chapters or books on
an even-numbered page.

If you don't like the default headers that @code{@@setchapternewpage}
sets, you can explicit control them with the @code{@@headings} command.
@xref{headings on off, , The @code{@@headings} Command}.

At the beginning of a manual or book, pages are not numbered---for
example, the title and copyright pages of a book are not numbered.  By
convention, table of contents and frontmatter pages are numbered with
roman numerals and not in sequence with the rest of the document.

Since an Info file does not have pages, the @code{@@setchapternewpage}
command has no effect on it.

We recommend not including any @code{@@setchapternewpage} command in
your manual sources at all, since the desired output is not intrinsic to
the document.  For a particular hard copy run, if you don't want the
default option (no blank pages, same headers on all pages) use the
@option{--texinfo} option to @command{texi2dvi} to specify the output
you want.


@node paragraphindent
@subsection @code{@@paragraphindent}: Paragraph Indenting
@cindex Indenting paragraphs, control of
@cindex Paragraph indentation control
@findex paragraphindent

The Texinfo processors may insert whitespace at the beginning of the
first line of each paragraph, thereby indenting that paragraph.  You can
use the @code{@@paragraphindent} command to specify this indentation.
Write an @code{@@paragraphindent} command at the beginning of a line
followed by either @samp{asis} or a number:

@example
@@paragraphindent @var{indent}
@end example

The indentation is according to the value of @var{indent}:

@table @asis
@item @code{asis}
Do not change the existing indentation (not implemented in @TeX{}).

@item @code{none}
@itemx 0
Omit all indentation.

@item @var{n}
Indent by @var{n} space characters in Info output, by @var{n} ems in
@TeX{}.

@end table

The default value of @var{indent} is 3.  @code{@@paragraphindent} is
ignored for HTML output.

It is best to write the @code{@@paragraphindent} command before the
end-of-header line at the beginning of a Texinfo file, so the region
formatting commands indent paragraphs as specified.  @xref{Start of
Header}.

A peculiarity of the @code{texinfo-format-buffer} and
@code{texinfo-format-region} commands is that they do not indent (nor
fill) paragraphs that contain @code{@@w} or @code{@@*} commands.


@node firstparagraphindent
@subsection @code{@@firstparagraphindent}: Indenting After Headings
@cindex First paragraph, suppressing indentation of
@cindex Suppressing first paragraph indentation
@cindex Preventing first paragraph indentation
@cindex Indenting, suppressing of first paragraph
@cindex Headings, indentation after
@findex firstparagraphindent

As you can see in the present manual, the first paragraph in any
section is not indented by default.  Typographically, indentation is a
paragraph separator, which means that it is unnecessary when a new
section begins.  This indentation is controlled with the
@code{@@firstparagraphindent} command:

@example
@@firstparagraphindent @var{word}
@end example

The first paragraph after a heading is indented according to the value
of @var{word}:

@table @asis
@item @code{none}
Prevents the first paragraph from being indented (default).
This option is ignored by @command{makeinfo} if
@code{@@paragraphindent asis} is in effect.

@item @code{insert}
Include normal paragraph indentation.  This respects the paragraph
indentation set by a @code{@@paragraphindent} command
(@pxref{paragraphindent}).
@end table

For HTML and XML output, the @code{@@firstparagraphindent} setting is
ignored.

It is best to write the @code{@@paragraphindent} command before the
end-of-header line at the beginning of a Texinfo file, so the region
formatting commands indent paragraphs as specified.  @xref{Start of
Header}.


@node exampleindent
@subsection @code{@@exampleindent}: Environment Indenting
@cindex Indenting environments
@cindex Environment indentation
@cindex Example indentation
@findex exampleindent

The Texinfo processors indent each line of @code{@@example} and similar
environments.  You can use the @code{@@exampleindent} command to specify
this indentation.  Write an @code{@@exampleindent} command at the
beginning of a line followed by either @samp{asis} or a number:

@example
@@exampleindent @var{indent}
@end example

@code{@@exampleindent} is ignored for HTML output.  Otherwise, the
indentation is according to the value of @var{indent}:

@table @asis
@item @code{asis}
Do not change the existing indentation (not implemented in @TeX{}).

@item 0
Omit all indentation.

@item @var{n}
Indent environments by @var{n} space characters in Info output, by
@var{n} ems in @TeX{}.

@end table

The default value of @var{indent} is 5 spaces in Info, and 0.4@dmn{in}
in @TeX{}, which is somewhat less.  (The reduction is to help @TeX{}
fit more characters onto physical lines.)

It is best to write the @code{@@exampleindent} command before the
end-of-header line at the beginning of a Texinfo file, so the region
formatting commands indent paragraphs as specified.  @xref{Start of
Header}.


@node Software Copying Permissions
@section Software Copying Permissions
@cindex Software copying permissions
@cindex Copying software
@cindex Distribution
@cindex License agreement

If the Texinfo file has a section containing the ``General Public
License'' and the distribution information and a warranty disclaimer for
the software that is documented, we recommend placing this right after
the `Top' node.  The General Public License is very important to Project
GNU software.  It ensures that you and others will continue to have a
right to use and share the software.

The copying and distribution information and the disclaimer are followed
by an introduction or else by the first chapter of the manual.

@cindex Introduction, as part of file
Although an introduction is not a required part of a Texinfo file, it
is very helpful.  Ideally, it should state clearly and concisely what
the file is about and who would be interested in reading it.  In
general, an introduction would follow the licensing and distribution
information, although sometimes people put it earlier in the document.


@node Ending a File
@chapter Ending a Texinfo File
@cindex Ending a Texinfo file
@cindex Texinfo file ending
@cindex File ending
@findex bye

The end of a Texinfo file should include commands to create indices,
and the @code{@@bye} command to mark the last line to be processed.

For example:

@example
@@node Index
@@unnumbered Index

@@printindex cp

@@bye
@end example

@menu
* Printing Indices & Menus::    How to print an index in hardcopy and
                                 generate index menus in Info.
* File End::                    How to mark the end of a file.
@end menu


@node Printing Indices & Menus
@section Printing Indices and Menus
@cindex Printing an index
@cindex Indices, printing and menus
@cindex Generating menus with indices
@cindex Menus generated with indices

To print an index means to include it as part of a manual or Info file.
This does not happen automatically just because you use @code{@@cindex}
or other index-entry generating commands in the Texinfo file; those just
cause the raw data for the index to be accumulated.  To generate an
index, you must include the @code{@@printindex} command at the place in
the document where you want the index to appear.  Also, as part of the
process of creating a printed manual, you must run a program called
@code{texindex} (@pxref{Hardcopy}) to sort the raw data to produce a
sorted index file.  The sorted index file is what is actually used to
print the index.

Texinfo offers six separate types of predefined index, which suffice
in most cases.  @xref{Indices}, for information on this, as well
defining your own new indices, combining indices, and, most
importantly advice on writing the actual index entries.  This section
focuses on printing indices, which is done with the
@code{@@printindex} command.

@findex printindex
@code{@@printindex} takes one argument, a two-letter index
abbreviation.  It reads the corresponding sorted index file (for
printed output), and formats it appropriately into an index.

The @code{@@printindex} command does not generate a chapter heading
for the index, since different manuals have different needs.
Consequently, you should precede the @code{@@printindex} command with
a suitable section or chapter command (usually @code{@@appendix} or
@code{@@unnumbered}) to supply the chapter heading and put the index
into the table of contents.  Precede the chapter heading with an
@code{@@node} line as usual.

For example:

@smallexample
@group
@@node Variable Index
@@unnumbered Variable Index

@@printindex vr
@end group

@group
@@node Concept Index
@@unnumbered Concept Index

@@printindex cp
@end group
@end smallexample

If you have more than one index, we recommend placing the concept index last.

@itemize
@item
In printed output, @code{@@printindex} produces a traditional
two-column index, with dot leaders between the index terms and page
numbers.

@item
In Info output, @code{@@printindex} produces a special menu containing
the line number of the entry, relative to the start of the node.  Info
readers can use this to go to the exact line of an entry, not just the
containing node.  (Older Info readers will just go to the node.)
Here's an example:

@smallexample
* First index entry:   Top.   (line  7)
@end smallexample

@noindent The actual number of spaces is variable, to right-justify
the line number; it's been reduced here to make the line fit in the
printed manual.

@item
In plain text output, @code{@@printindex} produces the same menu, but
the line numbers are relative to the start of the file, since that's
more convenient for that format.

@item
In HTML and Docbook output, @code{@@printindex} produces links
to the index entries.

@item
In XML output, it simply records the index to be printed.
@end itemize

It's not possible to generate an index when writing to standard
output; @command{makeinfo} generates a warning in this case.


@node File End
@section @code{@@bye} File Ending
@findex bye

An @code{@@bye} command terminates Texinfo processing.  None of the
formatters read anything following @code{@@bye}.  The @code{@@bye}
command should be on a line by itself.

If you wish, you may follow the @code{@@bye} line with notes. These
notes will not be formatted and will not appear in either Info or a
printed manual; it is as if text after @code{@@bye} were within
@code{@@ignore} @dots{} @code{@@end ignore}.  Also, you may follow the
@code{@@bye} line with a local variables list for Emacs.
@xref{Compile-Command, , Using Local Variables and the Compile Command},
for more information.


@node Structuring
@chapter Chapter Structuring
@cindex Chapter structuring
@cindex Structuring of chapters

The @dfn{chapter structuring} commands divide a document into a hierarchy of
chapters, sections, subsections, and subsubsections.  These commands
generate large headings; they also provide information for the table
of contents of a printed manual (@pxref{Contents, , Generating a Table
of Contents}).@refill

The chapter structuring commands do not create an Info node structure,
so normally you should put an @code{@@node} command immediately before
each chapter structuring command (@pxref{Nodes}).  The only time you
are likely to use the chapter structuring commands without using the
node structuring commands is if you are writing a document that
contains no cross references and will never be transformed into Info
format.@refill

It is unlikely that you will ever write a Texinfo file that is
intended only as an Info file and not as a printable document.  If you
do, you might still use chapter structuring commands to create a
heading at the top of each node---but you don't need to.@refill

@menu
* Tree Structuring::            A manual is like an upside down tree @dots{}
* Structuring Command Types::   How to divide a manual into parts.
* makeinfo top::                The @code{@@top} command, part of the `Top' node.
* chapter::
* unnumbered & appendix::
* majorheading & chapheading::
* section::
* unnumberedsec appendixsec heading::
* subsection::
* unnumberedsubsec appendixsubsec subheading::
* subsubsection::               Commands for the lowest level sections.
* Raise/lower sections::        How to change commands' hierarchical level.
@end menu


@node Tree Structuring
@section Tree Structure of Sections
@cindex Tree structuring

A Texinfo file is usually structured like a book with chapters,
sections, subsections, and the like.  This structure can be visualized
as a tree (or rather as an upside-down tree) with the root at the top
and the levels corresponding to chapters, sections, subsection, and
subsubsections.@refill

Here is a diagram that shows a Texinfo file with three chapters,
each of which has two sections.@refill

@example
@group
                         Top
                          |
        -------------------------------------
       |                  |                  |
    Chapter 1          Chapter 2          Chapter 3
       |                  |                  |
    --------           --------           --------
   |        |         |        |         |        |
Section  Section   Section  Section   Section  Section
  1.1      1.2       2.1      2.2       3.1      3.2

@end group
@end example

In a Texinfo file that has this structure, the beginning of Chapter 2
looks like this:@refill

@example
@group
@@node    Chapter 2,  Chapter 3, Chapter 1, top
@@chapter Chapter 2
@end group
@end example

The chapter structuring commands are described in the sections that
follow; the @code{@@node} and @code{@@menu} commands are described in
following chapters. (@xref{Nodes}, and see @ref{Menus}.)@refill


@node Structuring Command Types
@section Structuring Command Types

The chapter structuring commands fall into four groups or series, each
of which contains structuring commands corresponding to the
hierarchical levels of chapters, sections, subsections, and
subsubsections.@refill

The four groups are the @code{@@chapter} series, the
@code{@@unnumbered} series, the @code{@@appendix} series, and the
@code{@@heading} series.@refill

Each command produces titles that have a different appearance on the
printed page or Info file; only some of the commands produce
titles that are listed in the table of contents of a printed book or
manual.@refill

@itemize @bullet
@item
The @code{@@chapter} and @code{@@appendix} series of commands produce
numbered or lettered entries both in the body of a printed work and in
its table of contents.@refill

@item
The @code{@@unnumbered} series of commands produce unnumbered entries
both in the body of a printed work and in its table of contents.  The
@code{@@top} command, which has a special use, is a member of this
series (@pxref{makeinfo top, , @code{@@top}}).  An @code{@@unnumbered}
section should be associated with a node and be a normal part of the
document structure.

@item
The @code{@@heading} series of commands produce simple unnumbered
headings that do not appear in a table of contents, are not associated
with nodes, and cannot be cross-referenced.  The heading commands
never start a new page.

@item
The @code{@@majorheading} command is similar to @code{@@chapheading},
except that it generates a larger vertical whitespace before the
heading.

@item
When an @code{@@setchapternewpage} command says to do so, the
@code{@@chapter}, @code{@@unnumbered}, and @code{@@appendix} commands
start new pages in the printed manual; the @code{@@heading} commands
do not.@refill
@end itemize

Here are the four groups of chapter structuring commands:

@tex
{\globaldefs = 1 \smallfonts}
@end tex

@multitable @columnfractions .19 .30 .29 .22
@item                        @tab                              @tab                       @tab No new page
@item @i{Numbered}           @tab @i{Unnumbered}               @tab @i{Lettered/numbered} @tab @i{Unnumbered}
@item In contents            @tab In contents                  @tab In contents           @tab Not in contents
@item                        @tab @code{@@top}                 @tab                       @tab @code{@@majorheading}
@item @code{@@chapter}       @tab @code{@@unnumbered}          @tab @code{@@appendix} @tab @code{@@chapheading}
@item @code{@@section}       @tab @code{@@unnumberedsec}       @tab @code{@@appendixsec} @tab @code{@@heading}
@item @code{@@subsection}    @tab @code{@@unnumberedsubsec}    @tab @code{@@appendixsubsec} @tab @code{@@subheading}
@item @code{@@subsubsection} @tab @code{@@unnumberedsubsubsec} @tab @code{@@appendixsubsubsec} @tab @code{@@subsubheading}
@end multitable
@tex
{\globaldefs = 1 \textfonts}
@end tex


@node makeinfo top
@section @code{@@top}

The @code{@@top} command is a special sectioning command that you use
only after an @samp{@@node Top} line at the beginning of a Texinfo file.
The @code{@@top} command tells the @code{makeinfo} formatter which node
is the `Top' node, so it can use it as the root of the node tree if your
manual uses implicit node pointers.  It has the same typesetting effect as
@code{@@unnumbered} (@pxref{unnumbered & appendix, , @code{@@unnumbered}
and @code{@@appendix}}).  For detailed information, see @ref{makeinfo
top command, , The @code{@@top} Command}.

The @code{@@top} node and its menu (if any) is conventionally wrapped in
an @code{@@ifnottex} conditional so that it will appear only in Info and
HTML output, not @TeX{}.


@node chapter
@comment  node-name,  next,  previous,  up
@section @code{@@chapter}
@findex chapter

@code{@@chapter} identifies a chapter in the document.  Write the
command at the beginning of a line and follow it on the same line by
the title of the chapter.@refill

For example, this chapter in this manual is entitled ``Chapter
Structuring''; the @code{@@chapter} line looks like this:@refill

@example
@@chapter Chapter Structuring
@end example

In @TeX{}, the @code{@@chapter} command creates a chapter in the
document, specifying the chapter title.  The chapter is numbered
automatically.@refill

In Info, the @code{@@chapter} command causes the title to appear on a
line by itself, with a line of asterisks inserted underneath.  Thus,
in Info, the above example produces the following output:@refill

@example
Chapter Structuring
*******************
@end example

@findex centerchap
Texinfo also provides a command @code{@@centerchap}, which is analogous
to @code{@@unnumbered}, but centers its argument in the printed output.
This kind of stylistic choice is not usually offered by Texinfo.
@c but the Hacker's Dictionary wanted it ...


@node unnumbered & appendix
@section @code{@@unnumbered} and @code{@@appendix}
@findex unnumbered
@findex appendix

Use the @code{@@unnumbered} command to create a chapter that appears
in a printed manual without chapter numbers of any kind.  Use the
@code{@@appendix} command to create an appendix in a printed manual
that is labelled by letter (`A', `B', @dots{}) instead of by number.

Write an @code{@@appendix} or @code{@@unnumbered} command at the
beginning of a line and follow it on the same line by the title, as
you would if you were creating a chapter.


@node majorheading & chapheading
@section @code{@@majorheading}, @code{@@chapheading}
@findex majorheading
@findex chapheading

The @code{@@majorheading} and @code{@@chapheading} commands put
chapter-like headings in the body of a document.@refill

However, neither command causes @TeX{} to produce a numbered heading
or an entry in the table of contents; and neither command causes
@TeX{} to start a new page in a printed manual.@refill

In @TeX{}, an @code{@@majorheading} command generates a larger vertical
whitespace before the heading than an @code{@@chapheading} command but
is otherwise the same.

In Info,
the @code{@@majorheading} and
@code{@@chapheading} commands are equivalent to
@code{@@chapter}: the title is printed on a line by itself with a line
of asterisks underneath.  (@xref{chapter, , @code{@@chapter}}.)@refill


@node section
@section @code{@@section}
@findex section

A @code{@@section} command identifies a section within a chapter unit,
whether created with @code{@@chapter}, @code{@@unnumbered}, or
@code{@@appendix}, following the numbering scheme of the chapter-level
command.  Thus, within a @code{@@chapter} chapter numbered `1', the
section is numbered like `1.2'; within an @code{@@appendix}
``chapter'' labeled `A', the section is numbered like `A.2'; within an
@code{@@unnumbered} chapter, the section gets no number.

For example, this section is headed with an @code{@@section} command
and looks like this in the Texinfo file:

@example
@@section @@code@{@@@@section@}
@end example

To create a section, write the @code{@@section} command at the
beginning of a line and follow it on the same line by the section
title.  The output is underlined with @samp{=} in Info.

Thus,

@example
@@section This is a section
@end example

@noindent
might produce the following in Info:

@example
@group
5.7 This is a section
=====================
@end group
@end example


@node unnumberedsec appendixsec heading
@section @code{@@unnumberedsec}, @code{@@appendixsec}, @code{@@heading}
@findex unnumberedsec
@findex appendixsec
@findex heading

The @code{@@unnumberedsec}, @code{@@appendixsec}, and @code{@@heading}
commands are, respectively, the unnumbered, appendix-like, and
heading-like equivalents of the @code{@@section} command, as described
in the previous section.

@table @code
@item @@unnumberedsec
The @code{@@unnumberedsec} command may be used within an
unnumbered chapter or within a regular chapter or appendix to
provide an unnumbered section.@refill

@item @@appendixsec
@itemx @@appendixsection
@code{@@appendixsection} is a longer spelling of the
@code{@@appendixsec} command; the two are synonymous.@refill
@findex appendixsection

Conventionally, the @code{@@appendixsec} or @code{@@appendixsection}
command is used only within appendices.@refill

@item @@heading
You may use the @code{@@heading} command anywhere you wish for a
section-style heading that will not appear in the table of contents.@refill
@end table

@code{@@unnumberedsec} and @code{@@appendixsec} do not need to be used
in ordinary circumstances, because @code{@@section} may also be used
within @code{@@unnumbered} and @code{@@appendix} chapters; again, see
the previous section.


@node subsection
@section The @code{@@subsection} Command
@findex subsection

Subsections are to sections as sections are to chapters.
(@xref{section, , @code{@@section}}.)  In Info, subsection titles are
underlined with @samp{-}.  For example,

@example
@@subsection This is a subsection
@end example

@noindent
produces

@example
@group
1.2.3 This is a subsection
--------------------------
@end group
@end example

In a printed manual, subsections are listed in the table of contents
and are numbered three levels deep.@refill


@node unnumberedsubsec appendixsubsec subheading
@section The @code{@@subsection}-like Commands
@cindex Subsection-like commands
@findex unnumberedsubsec
@findex appendixsubsec
@findex subheading

The @code{@@unnumberedsubsec}, @code{@@appendixsubsec}, and
@code{@@subheading} commands are, respectively, the unnumbered,
appendix-like, and heading-like equivalents of the @code{@@subsection}
command.  (@xref{subsection, , @code{@@subsection}}.)

In Info, the @code{@@subsection}-like commands generate a title
underlined with hyphens.  In a printed manual, an @code{@@subheading}
command produces a heading like that of a subsection except that it is
not numbered and does not appear in the table of contents.  Similarly,
an @code{@@unnumberedsubsec} command produces an unnumbered heading like
that of a subsection and an @code{@@appendixsubsec} command produces a
subsection-like heading labelled with a letter and numbers; both of
these commands produce headings that appear in the table of
contents.

@code{@@unnumberedsubsec} and @code{@@appendixsubsec} do not need to
be used in ordinary circumstances, because @code{@@subsection} may
also be used within sections of @code{@@unnumbered} and
@code{@@appendix} chapters (@pxref{section,,@code{section}}).


@node subsubsection
@section The `subsub' Commands
@cindex Subsub commands
@findex subsubsection
@findex unnumberedsubsubsec
@findex appendixsubsubsec
@findex subsubheading

The fourth and lowest level sectioning commands in Texinfo are the
`subsub' commands.  They are:@refill

@table @code
@item @@subsubsection
Subsubsections are to subsections as subsections are to sections.
(@xref{subsection, , @code{@@subsection}}.)  In a printed manual,
subsubsection titles appear in the table of contents and are numbered
four levels deep.@refill

@item @@unnumberedsubsubsec
Unnumbered subsubsection titles appear in the table of contents of a
printed manual, but lack numbers.  Otherwise, unnumbered
subsubsections are the same as subsubsections.  In Info, unnumbered
subsubsections look exactly like ordinary subsubsections.@refill

@item @@appendixsubsubsec
Conventionally, appendix commands are used only for appendices and are
lettered and numbered appropriately in a printed manual.  They also
appear in the table of contents.  In Info, appendix subsubsections look
exactly like ordinary subsubsections.@refill

@item @@subsubheading
The @code{@@subsubheading} command may be used anywhere that you need
a small heading that will not appear in the table of contents.  In
Info, subsubheadings look exactly like ordinary subsubsection
headings.@refill
@end table

@code{@@unnumberedsubsubsec} and @code{@@appendixsubsubsec} do not
need to be used in ordinary circumstances, because
@code{@@subsubsection} may also be used within subsections of
@code{@@unnumbered} and @code{@@appendix} chapters
(@pxref{section,,@code{section}}).


In Info,  `subsub' titles are underlined with periods.
For example,@refill

@example
@@subsubsection This is a subsubsection
@end example

@noindent
produces

@example
@group
1.2.3.4 This is a subsubsection
...............................
@end group
@end example


@node Raise/lower sections
@section @code{@@raisesections} and @code{@@lowersections}
@findex raisesections
@findex lowersections
@cindex Raising and lowering sections
@cindex Lowering and raising sections
@cindex Sections, raising and lowering

The @code{@@raisesections} and @code{@@lowersections} commands
implicitly raise and lower the hierarchical level of following
chapters, sections and the other sectioning commands.

That is, the @code{@@raisesections} command changes sections to
chapters, subsections to sections, and so on.  Conversely, the
@code{@@lowersections} command changes chapters to sections, sections
to subsections, and so on.  Thus, an @code{@@lowersections} command
cancels an @code{@@raisesections} command, and vice versa.

@cindex Include files, and section levels
You can use @code{@@lowersections} to include text written as an outer
or standalone Texinfo file in another Texinfo file as an inner,
included file.  Typical usage looks like this:

@example
@@lowersections
@@include somefile.texi
@@raisesections
@end example

@noindent (Without the @code{@@raisesections}, all the subsequent
sections in the document would be lowered.)

If the included file being lowered has a @code{@@top} node, you'll
need to conditionalize its inclusion with a flag (@pxref{set value}).

Another difficulty can arise with documents that use the (recommended)
feature of @command{makeinfo} for implicitly determining node
pointers.  Since @command{makeinfo} must assume a hierarchically
organized document to determine the pointers, you cannot just
arbitrarily sprinkle @code{@@raisesections} and @code{@@lowersections}
commands in the document.  The final result has to have menus that
take the raising and lowering into account.  Therefore, as a practical
matter, you generally only want to raise or lower large chunks,
usually in external files as shown above.

Repeated use of the commands continue to raise or lower the
hierarchical level a step at a time.  An attempt to raise above
`chapter' reproduces chapter commands; an attempt to lower below
`subsubsection' reproduces subsubsection commands.  Also, lowered
subsubsections and raised chapters will not work with
@command{makeinfo}'s feature of implicitly determining node pointers,
since the menu structure won't be correct.

Write each @code{@@raisesections} and @code{@@lowersections} command
on a line of its own.


@node Nodes
@chapter Nodes

@dfn{Nodes} are the primary segments of a Texinfo file.  They do not
in and of themselves impose a hierarchical or any other kind of
structure on a file.  Nodes contain @dfn{node pointers} that name
other nodes, and can contain @dfn{menus} which are lists of nodes.  In
Info, the movement commands can carry you to a pointed-to node or to a
node listed in a menu.

Node pointers and menus provide structure for Info files just as
chapters, sections, subsections, and the like, provide structure for
printed books.

Because node names are used in cross-references, it is not desirable
to casually change them.  Such name changes invalidate references from
other manuals, from mail archives, and so on.

@menu
* Two Paths::                   Different commands to structure
                                 Info output and printed output.
* Node Menu Illustration::      A diagram, and sample nodes and menus.
* node::                        Creating nodes, in detail.
* makeinfo Pointer Creation::   Letting makeinfo determine node pointers.
* anchor::                      Defining arbitrary cross-reference targets.
@end menu


@node Two Paths
@section Two Paths

The node and menu commands and the chapter structuring commands are
technically independent of each other:

@itemize @bullet
@item
In Info, node and menu commands provide structure.  The chapter
structuring commands generate headings with different kinds of
underlining---asterisks for chapters, hyphens for sections, and so on;
they do nothing else.@refill

@item
In @TeX{}, the chapter structuring commands generate chapter and section
numbers and tables of contents.  The node and menu commands provide
information for cross references; they do nothing else.@refill
@end itemize

You can use node pointers and menus to structure an Info file any way
you want; and you can write a Texinfo file so that its Info output has a
different structure than its printed output.  However, virtually all
Texinfo files are written such that the structure for the Info output
corresponds to the structure for the printed output.  It is neither
convenient nor understandable to the reader to do otherwise.@refill

Generally, printed output is structured in a tree-like hierarchy in
which the chapters are the major limbs from which the sections branch
out.  Similarly, node pointers and menus are organized to create a
matching structure in the Info output.@refill


@node Node Menu Illustration
@section Node and Menu Illustration

Here is a copy of the diagram shown earlier that illustrates a Texinfo
file with three chapters, each of which contains two sections.@refill

The ``root'' is at the top of the diagram and the ``leaves'' are at the
bottom.  This is how such a diagram is drawn conventionally; it
illustrates an upside-down tree.  For this reason, the root node is
called the `Top' node, and `Up' node pointers carry you closer to the
root.@refill

@example
@group
                         Top
                          |
        -------------------------------------
       |                  |                  |
    Chapter 1          Chapter 2          Chapter 3
       |                  |                  |
    --------           --------           --------
   |        |         |        |         |        |
Section  Section   Section  Section   Section  Section
  1.1      1.2       2.1      2.2       3.1      3.2
@end group
@end example

The fully-written command to start Chapter 2 would be this:

@example
@group
@@node     Chapter 2,  Chapter 3, Chapter 1, Top
@@comment  node-name,  next,      previous,  up
@end group
@end example

@noindent
This @code{@@node} line says that the name of this node is ``Chapter
2'', the name of the `Next' node is ``Chapter 3'', the name of the
`Previous' node is ``Chapter 1'', and the name of the `Up' node is
``Top''.  You can omit writing out these node names if your document is
hierarchically organized (@pxref{makeinfo Pointer Creation}), but the
pointer relationships still obtain.

@quotation Note
@strong{Please Note:} `Next' refers to the next node at the same
hierarchical level in the manual, not necessarily to the next node
within the Texinfo file.  In the Texinfo file, the subsequent node may
be at a lower level---a section-level node most often follows a
chapter-level node, for example.  `Next' and `Previous' refer to nodes
at the @emph{same} hierarchical level.  (The `Top' node contains the
exception to this rule.  Since the `Top' node is the only node at that
level, `Next' refers to the first following node, which is almost always
a chapter or chapter-level node.)@refill
@end quotation

To go to Sections 2.1 and 2.2 using Info, you need a menu inside Chapter
2.  (@xref{Menus}.)  You would write the menu just
before the beginning of Section 2.1, like this:@refill

@example
@group
   @@menu
   * Sect. 2.1::    Description of this section.
   * Sect. 2.2::
   @@end menu
@end group
@end example

Write the node for Sect. 2.1 like this:@refill

@example
@group
   @@node     Sect. 2.1, Sect. 2.2, Chapter 2, Chapter 2
   @@comment  node-name, next,      previous,  up
@end group
@end example

In Info format, the `Next' and `Previous' pointers of a node usually
lead to other nodes at the same level---from chapter to chapter or from
section to section (sometimes, as shown, the `Previous' pointer points
up); an `Up' pointer usually leads to a node at the level above (closer
to the `Top' node); and a `Menu' leads to nodes at a level below (closer
to `leaves').  (A cross reference can point to a node at any level;
see @ref{Cross References}.)@refill

Usually, an @code{@@node} command and a chapter structuring command are
used in sequence, along with indexing commands.  (You may follow the
@code{@@node} line with a comment line that reminds you which pointer is
which.)@refill

Here is the beginning of the chapter in this manual called ``Ending a
Texinfo File''.  This shows an @code{@@node} line followed by a comment
line, an @code{@@chapter} line, and then by indexing lines.@refill

@example
@group
@@node    Ending a File, Structuring, Beginning a File, Top
@@comment node-name,     next,        previous,         up
@@chapter Ending a Texinfo File
@@cindex Ending a Texinfo file
@@cindex Texinfo file ending
@@cindex File ending
@end group
@end example


@node node
@section The @code{@@node} Command

@cindex Node, defined
@findex node

A @dfn{node} is a segment of text that begins at an @code{@@node}
command and continues until the next @code{@@node} command.  The
definition of node is different from that for chapter or section.  A
chapter may contain sections and a section may contain subsections;
but a node cannot contain subnodes; the text of a node continues only
until the next @code{@@node} command in the file.  A node usually
contains only one chapter structuring command, the one that follows
the @code{@@node} line.  On the other hand, in printed output nodes
are used only for cross references, so a chapter or section may
contain any number of nodes.  Indeed, a chapter usually contains
several nodes, one for each section, subsection, and
subsubsection.

To specify a node, write an @code{@@node} command at the beginning of
a line, and follow it with up to four arguments, separated by commas,
on the rest of the same line.  The first argument is required; it is
the name of this node (for details of node names, @pxref{Node Line
Requirements}).  The subsequent arguments are the names of the `Next',
`Previous', and `Up' pointers, in that order, and may be omitted if
your Texinfo document is hierarchically organized (@pxref{makeinfo
Pointer Creation}).

@opindex accesskey@r{, in HTML output}
Whether the node pointers are specified implicitly or explicitly, the
HTML output from @command{makeinfo} for each node includes links to
the `Next', `Previous', and `Up' nodes.  The HTML also uses the
@code{accesskey} attribute with the values @samp{n}, @samp{p}, and
@samp{u} respectively.  This allows people using web browsers to
follow the nagivation using (typically) @kbd{M-@var{letter}}, e.g.,
@kbd{M-n} for the `Next' node, from anywhere within the node.

You may insert spaces before each name on the @code{@@node} line if
you wish; the spaces are ignored.  You must write the name of the node
and (if present) the names of the `Next', `Previous', and `Up'
pointers all on the same line.  Otherwise, the formatters fail.
(@inforef{Top, info, info}, for more information about nodes in Info.)

Usually, you write one of the chapter-structuring command lines
immediately after an @code{@@node} line---for example, an
@code{@@section} or @code{@@subsection} line.  (@xref{Structuring
Command Types}.)

@TeX{} uses @code{@@node} lines to identify the names to use for cross
references.  For this reason, you must write @code{@@node} lines in a
Texinfo file that you intend to format for printing, even if you do not
intend to format it for Info.  (Cross references, such as the one at the
end of this sentence, are made with @code{@@xref} and related commands;
see @ref{Cross References}.)

@menu
* Node Names::                  How to choose node and pointer names.
* Writing a Node::              How to write an @code{@@node} line.
* Node Line Tips::              Keep names short.
* Node Line Requirements::      Keep names unique, without @@-commands.
* First Node::                  How to write a `Top' node.
* makeinfo top command::        How to use the @code{@@top} command.
@end menu


@node Node Names
@subsection Choosing Node and Pointer Names

@cindex Node names, choosing
The name of a node identifies the node (for details of node names,
@pxref{Node Line Requirements}).  The pointers enable you to reach
other nodes and consist simply of the names of those nodes.

Normally, a node's `Up' pointer contains the name of the node whose
menu mentions that node.  The node's `Next' pointer contains the name
of the node that follows the present node in that menu and its
`Previous' pointer contains the name of the node that precedes it in
that menu.  When a node's `Previous' node is the same as its `Up'
node, both node pointers name the same node.

Usually, the first node of a Texinfo file is the `Top' node, and its
`Up' and `Previous' pointers point to the @file{dir} file, which
contains the main menu for all of Info.

The `Top' node itself contains the main or master menu for the manual.
Also, it is helpful to include a brief description of the manual in the
`Top' node.  @xref{First Node}, for information on how to write the
first node of a Texinfo file.

Even when you explicitly specify all pointers, that does not mean you
can write the nodes in the Texinfo source file in an arbitrary order!
Because @TeX{} processes the file sequentially, irrespective of node
pointers, you must write the nodes in the order you wish them to appear
in the output.


@node Writing a Node
@subsection How to Write an @code{@@node} Line
@cindex Writing an @code{@@node} line
@cindex @code{@@node} line writing
@cindex Node line writing

The easiest way to write an @code{@@node} line is to write @code{@@node}
at the beginning of a line and then the name of the node, like
this:

@example
@@node @var{node-name}
@end example

If you are using GNU Emacs, you can use the update node commands
provided by Texinfo mode to insert the names of the pointers; or you
can leave the pointers out of the Texinfo file and let @code{makeinfo}
insert node pointers into the Info file it creates.  (@xref{Texinfo
Mode}, and @ref{makeinfo Pointer Creation}.)

Alternatively, you can insert the `Next', `Previous', and `Up'
pointers yourself.  If you do this, you may find it helpful to use the
Texinfo mode keyboard command @kbd{C-c C-c n}.  This command inserts
@samp{@@node} and a comment line listing the names of the pointers in
their proper order.  The comment line helps you keep track of which
arguments are for which pointers.  This comment line is especially useful
if you are not familiar with Texinfo.

The template for a fully-written-out node line with `Next', `Previous',
and `Up' pointers looks like this:

@example
@@node @var{node-name}, @var{next}, @var{previous}, @var{up}
@end example

The @var{node-name} argument must be present, but the others are
optional.  If you wish to specify some but not others, just insert
commas as needed, as in: @samp{@@node mynode,,,uppernode}.  However,
we recommend leaving off all the pointers and letting @code{makeinfo}
determine them, as described above.

If you wish, you can ignore @code{@@node} lines altogether in your first
draft and then use the @code{texinfo-insert-node-lines} command to
create @code{@@node} lines for you.  However, we do not recommend this
practice.  It is better to name the node itself at the same time that
you write a segment so you can easily make cross references.  A large
number of cross references are an especially important feature of a good
Info file.

After you have inserted an @code{@@node} line, you should immediately
write an @@-command for the chapter or section and insert its name.
Next (and this is important!), put in several index entries.  Usually,
you will find at least two and often as many as four or five ways of
referring to the node in the index.  Use them all.  This will make it
much easier for people to find the node.


@node Node Line Tips
@subsection @code{@@node} Line Tips

Here are three suggestions:

@itemize @bullet
@item
Try to pick node names that are informative but short.@refill

In the Info file, the file name, node name, and pointer names are all
inserted on one line, which may run into the right edge of the window.
(This does not cause a problem with Info, but is ugly.)@refill

@item
Try to pick node names that differ from each other near the beginnings
of their names.  This way, it is easy to use automatic name completion in
Info.@refill

@item
By convention, node names are capitalized just as they would be for
section or chapter titles---initial and significant words are
capitalized; others are not.@refill
@end itemize


@node Node Line Requirements
@subsection @code{@@node} Line Requirements

@cindex Node line requirements
@cindex Restrictions on node names
Here are several requirements for @code{@@node} lines:

@itemize @bullet
@cindex Unique nodename requirement
@cindex Node name must be unique
@item
All the node names for a single Info file must be unique.

Duplicates confuse the Info movement commands.  This means, for
example, that if you end every chapter with a summary, you must name
each summary node differently.  You cannot just call each one
``Summary''.  You may, however, duplicate the titles of chapters, sections,
and the like.  Thus you can end each chapter in a book with a section
called ``Summary'', so long as the node names for those sections are all
different.

@item
A pointer name must be the name of a node.

The node to which a pointer points may come before or after the
node containing the pointer.

@cindex @@-commands in nodename
@cindex Node name, should not contain @@-commands
@item
@@-commands in node names are not allowed.  This includes punctuation
characters that are escaped with a @samp{@@}, such as @code{@@} and
@code{@{}, and accent commands such as @samp{@@'}.  (For a few cases
when this is useful, Texinfo has limited support for using
@w{@@-commands} in node names; see @ref{Pointer Validation}.)  Perhaps
this limitation will be removed some day.

@item
@cindex Colon in nodename
@cindex Comma in nodename
@cindex Parentheses in nodename
@cindex Period in nodename
@cindex Characters, invalid in node name
@cindex Invalid characters in node names
@cindex Node names, invalid characters in
Unfortunately, you cannot use periods, commas, colons or parentheses
within a node name; these confuse the Texinfo processors.  Perhaps
this limitation will be removed some day, too.

@need 700
For example, the following is a section title in this manual:

@smallexample
@@code@{@@@@unnumberedsec@}, @@code@{@@@@appendixsec@}, @@code@{@@@@heading@}
@end smallexample

@noindent
But the corresponding node name lacks the commas and the @@'s:

@smallexample
unnumberedsec appendixsec heading
@end smallexample

@cindex Case in node name
@item
Case is significant in node names.

@cindex White space in node name
@cindex Spaces in node name
Spaces before and after names on the @samp{@@node} line are ignored,
but spaces ``inside'' a name are significant.  For example:

@example
@@node  foo bar,
@@node foo bar ,
@@node  foo bar ,
@end example

@noindent all define the same node, @samp{foo bar}.  References to the
node should all use that name, without the leading or trailing spaces,
but with the internal spaces.
@end itemize


@node First Node
@subsection The First Node
@cindex Top node is first
@cindex First node

The first node of a Texinfo file is the @dfn{Top} node, except in an
included file (@pxref{Include Files}).  The Top node should contain a
short summary, copying permissions, and a master menu.  @xref{The Top
Node}, for more information on the Top node contents and examples.

Here is a description of the node pointers to be used in the Top node:

@itemize @bullet

@item
@cindex Up node of Top node
@cindex (dir) as Up node of Top node
The Top node (which must be named @samp{top} or @samp{Top}) should have
as its `Up' node the name of a node in another file, where there is a
menu that leads to this file.  Specify the file name in parentheses.

Usually, all Info files are installed in the same Info directory tree;
in this case, use @samp{(dir)} as the parent of the Top node; this is
short for @samp{(dir)top}, and specifies the Top node in the @file{dir}
file, which contains the main menu for the Info system as a whole.

@item
@cindex Prev node of Top node
The `Prev' node of the Top node should also be your @samp{(dir)} file.

@item
@cindex Next node of Top node
The `Next' node of the Top node should be the first chapter in your
document.

@end itemize

@xref{Installing an Info File}, for more information about installing
an Info file in the @file{info} directory.

It is usually best to leave the pointers off entirely and let the
tools implicitly define them, with this simple result:

@example
@@node Top
@end example


@node makeinfo top command
@subsection The @code{@@top} Sectioning Command
@findex top @r{(@@-command)}

A special sectioning command, @code{@@top} should be used with the
@code{@@node Top} line.  The @code{@@top} sectioning command tells
@code{makeinfo} that it marks the `Top' node in the file.  It provides
the information that @code{makeinfo} needs to insert node pointers
automatically.  Write the @code{@@top} command at the beginning of the
line immediately following the @code{@@node Top} line.  Write the title
on the remaining part of the same line as the @code{@@top} command.

In Info, the @code{@@top} sectioning command causes the title to appear
on a line by itself, with a line of asterisks inserted underneath, as
other sectioning commands do.

In @TeX{} and @code{texinfo-format-buffer}, the @code{@@top}
sectioning command is merely a synonym for @code{@@unnumbered}.
Neither of these formatters require an @code{@@top} command, and do
nothing special with it.  You can use @code{@@chapter} or
@code{@@unnumbered} after the @code{@@node Top} line when you use
these formatters.  Also, you can use @code{@@chapter} or
@code{@@unnumbered} when you use the Texinfo updating commands to
create or update pointers and menus.

Thus, in practice, a Top node starts like this:

@example
@@node Top
@@top Your Manual Title
@end example


@node makeinfo Pointer Creation
@section Creating Pointers with @code{makeinfo}
@cindex Creating pointers with @code{makeinfo}
@cindex Pointer creation with @code{makeinfo}
@cindex Automatic pointer creation with @code{makeinfo}

The @code{makeinfo} program has a feature for automatically
determining node pointers for a hierarchically organized document.  We
highly recommend using it.

When you take advantage of this feature, you do not need to write the
`Next', `Previous', and `Up' pointers after the name of a node.
However, you must write a sectioning command, such as @code{@@chapter}
or @code{@@section}, on the line immediately following each truncated
@code{@@node} line (except that comment lines may intervene).

In addition, you must follow the `Top' @code{@@node} line with a line
beginning with @code{@@top} to mark the `Top' node in the
file.  @xref{makeinfo top, , @code{@@top}}.

Finally, you must write the name of each node (except for the `Top'
node) in a menu that is one or more hierarchical levels above the
node's hierarchical level.

@cindex Detail menu
@findex detailmenu
If you use a detailed menu in your master menu (@pxref{Master Menu
Parts}), mark it with the @code{@@detailmenu @@dots@{@} @@end
detailmenu} environment, or @command{makeinfo} will get confused,
typically about the last and/or first node in the document.

This implicit node pointer creation feature in @code{makeinfo}
relieves you from the need to update menus and pointers manually or
with Texinfo mode commands.  (@xref{Updating Nodes and Menus}.)

In most cases, you will want to take advantage of this feature and not
redundantly specify node pointers.  However, Texinfo documents are not
required to be organized hierarchically or in fact to contain
sectioning commands at all (for example, if you never intend the
document to be printed).  The special procedure for handling the short
text before a menu (@pxref{Menus}) also disables this
feature, for that group of nodes.  In those cases, you will need to
explicitly specify all pointers.

@node anchor
@section @code{@@anchor}: Defining Arbitrary Cross-reference Targets

@findex anchor
@cindex Anchors
@cindex Cross-reference targets, arbitrary
@cindex Targets for cross-references, arbitrary

An @dfn{anchor} is a position in your document, labeled so that
cross-references can refer to it, just as they can to nodes.  You create
an anchor with the @code{@@anchor} command, and give the label as a
normal brace-delimited argument.  For example:

@example
This marks the @@anchor@{x-spot@}spot.
@dots{}
@@xref@{x-spot,,the spot@}.
@end example

@noindent produces:

@example
This marks the spot.
@dots{}
See [the spot], page 1.
@end example

As you can see, the @code{@@anchor} command itself produces no output.
This example defines an anchor `x-spot' just before the word `spot'.
You can refer to it later with an @code{@@xref} or other cross-reference
command, as shown.  @xref{Cross References}, for details on the
cross-reference commands.

It is best to put @code{@@anchor} commands just before the position you
wish to refer to; that way, the reader's eye is led on to the correct
text when they jump to the anchor.  You can put the @code{@@anchor}
command on a line by itself if that helps readability of the source.
Whitespace (including newlines) is ignored after @code{@@anchor}.

Anchor names and node names may not conflict.  Anchors and nodes are
given similar treatment in some ways; for example, the @code{goto-node}
command in standalone Info takes either an anchor name or a node name as
an argument.  (@xref{goto-node,,,info-stnd,GNU Info}.)

Also like node names, anchor names cannot include some characters
(@pxref{Node Line Requirements}).


@node Menus
@chapter Menus
@cindex Menus
@findex menu

@dfn{Menus} contain pointers to subordinate nodes.  In online output,
you use menus to go to such nodes.  Menus have no effect in printed
manuals and do not appear in them.

A node with a menu should not contain much text.  If you find yourself
writing a lot of text before a menu, we generally recommend moving
most of the text into a new subnode---all but a paragraph or two.
Otherwise, a reader with a terminal that displays only a few lines may
miss the menu and its associated text.  As a practical matter, it is
best to locate a menu within 20 or so lines of the beginning of the
node.

@menu
* Menu Location::               Menus go at the ends of short nodes.
* Writing a Menu::              What is a menu?
* Menu Parts::                  A menu entry has three parts.
* Less Cluttered Menu Entry::   Two part menu entry.
* Menu Example::                Two and three part menu entries.
* Other Info Files::            How to refer to a different Info file.
@end menu


@node Menu Location
@section Menu Location
@cindex Menu location
@cindex Location of menus

A menu must be located at the end of a node, without any regular text
or additional commands between the @code{@@end menu} and the beginning
of the next node.  (As a consequence, there may be at most one menu in
a node.)

@cindex Info format, and menus
This is actually a useful restriction, since a reader who uses the
menu could easily miss any such text.  Technically, it is necessary
because in Info format, there is no marker for the end of a menu, so
Info-reading programs would have no way to know when the menu ends and
normal text resumes.

@cindex Hierarchical documents, and menus
Technically, menus can carry you to any node, regardless of the
structure of the document; even to nodes in a different Info file.
However, we do not recommend ever making use of this, because the
@command{makeinfo} implicit pointer creation feature (@pxref{makeinfo
Pointer Creation}) and GNU Emacs Texinfo mode updating commands work
only to create menus of subordinate nodes in a hierarchically
structured document.  Instead, use cross references to refer to
arbitrary nodes.

In the past, we recommended using a @samp{@@heading} command within an
@code{@@ifinfo} conditional instead of the normal sectioning commands
after a very short node with a menu.  This had the advantage of making
the printed output look better, because there was no very short text
between two headings on the page.  But this also does not work with
@command{makeinfo}'s implicit pointer creation, and it also makes the
XML output incorrect, since it does not reflect the true document
structure.  So, regrettably, we can no longer recommend this.


@node Writing a Menu
@section Writing a Menu
@cindex Writing a menu
@cindex Menu writing

A menu consists of an @code{@@menu} command on a line by itself
followed by menu entry lines or menu comment lines and then by an
@code{@@end menu} command on a line by itself.

A menu looks like this:

@example
@group
@@menu
Larger Units of Text

* Files::                       All about handling files.
* Multiples: Buffers.           Multiple buffers; editing
                                 several files at once.
@@end menu
@end group
@end example

In a menu, every line that begins with an @w{@samp{* }} is a @dfn{menu
entry}.  (Note the space after the asterisk.)  A line that does not
start with an @w{@samp{* }} may also appear in a menu.  Such a line is
not a menu entry but is a menu comment line that appears in the Info
file.  In the example above, the line @samp{Larger Units of Text} is a
menu comment line; the two lines starting with @w{@samp{* }} are menu
@cindex Spaces, in menus
entries.  Space characters in a menu are preserved as-is; this allows
you to format the menu as you wish.

@opindex accesskey@r{, in HTML output}
In the HTML output from @command{makeinfo}, the @code{accesskey}
attribute is used with the values @samp{1}@dots{}@samp{9} for the
first nine entries.  This allows people using web browsers to follow
the first menu entries using (typically) @kbd{M-@var{digit}}, e.g.,
@kbd{M-1} for the first entry.


@node Menu Parts
@section The Parts of a Menu
@cindex Parts of a menu
@cindex Menu parts
@cindex @code{@@menu} parts

A menu entry has three parts, only the second of which is required:

@enumerate
@item
The menu entry name (optional).

@item
The name of the node (required).

@item
A description of the item (optional).
@end enumerate

The template for a generic menu entry looks like this (but see the
next section for one more possibility):

@example
* @var{menu-entry-name}: @var{node-name}.   @var{description}
@end example

Follow the menu entry name with a single colon and follow the node name
with tab, comma, newline, or the two characters period and space
(@samp{. }).

In Info, a user selects a node with the @kbd{m} (@code{Info-menu})
command.  The menu entry name is what the user types after the @kbd{m}
command.

The third part of a menu entry is a descriptive phrase or sentence.
Menu entry names and node names are often short; the description
explains to the reader what the node is about.  A useful description
complements the node name rather than repeats it.  The description,
which is optional, can spread over two or more lines; if it does, some
authors prefer to indent the second line while others prefer to align it
with the first (and all others).  It's up to you.


@node Less Cluttered Menu Entry
@section Less Cluttered Menu Entry
@cindex Two part menu entry
@cindex Double-colon menu entries
@cindex Menu entries with two colons
@cindex Less cluttered menu entry
@cindex Uncluttered menu entry

When the menu entry name and node name are the same, you can write
the name immediately after the asterisk and space at the beginning of
the line and follow the name with two colons.

@need 800
For example, write

@example
* Name::                        @var{description}
@end example

@need 800
@noindent
instead of

@example
* Name: Name.                   @var{description}
@end example

You should indeed use the node name for the menu entry name whenever
possible, since it reduces visual clutter in the menu.


@node Menu Example
@section A Menu Example
@cindex Menu example
@cindex Example menu

A menu looks like this in Texinfo:@refill

@example
@group
@@menu
* menu entry name: Node name.   A short description.
* Node name::                   This form is preferred.
@@end menu
@end group
@end example

@need 800
@noindent
This produces:

@example
@group
* menu:

* menu entry name: Node name.   A short description.
* Node name::                   This form is preferred.
@end group
@end example

@need 700
Here is an example as you might see it in a Texinfo file:@refill

@example
@group
@@menu
Larger Units of Text

* Files::                       All about handling files.
* Multiples: Buffers.           Multiple buffers; editing
                                 several files at once.
@@end menu
@end group
@end example

@need 800
@noindent
This produces:

@example
@group
* menu:
Larger Units of Text

* Files::                       All about handling files.
* Multiples: Buffers.           Multiple buffers; editing
                                 several files at once.
@end group
@end example

In this example, the menu has two entries.  @samp{Files} is both a menu
entry name and the name of the node referred to by that name.
@samp{Multiples} is the menu entry name; it refers to the node named
@samp{Buffers}. The line @samp{Larger Units of Text} is a comment; it
appears in the menu, but is not an entry.@refill

Since no file name is specified with either @samp{Files} or
@samp{Buffers}, they must be the names of nodes in the same Info file
(@pxref{Other Info Files, , Referring to Other Info Files}).@refill

@node Other Info Files
@comment  node-name,  next,  previous,  up
@section Referring to Other Info Files
@cindex Referring to other Info files
@cindex Nodes in other Info files
@cindex Other Info files' nodes
@cindex Going to other Info files' nodes
@cindex Info; other files' nodes

You can create a menu entry that enables a reader in Info to go to a
node in another Info file by writing the file name in parentheses just
before the node name.  In this case, you should use the three-part menu
entry format, which saves the reader from having to type the file
name.@refill

@need 800
The format looks like this:@refill

@example
@group
@@menu
* @var{first-entry-name}:(@var{filename})@var{nodename}.     @var{description}
* @var{second-entry-name}:(@var{filename})@var{second-node}. @var{description}
@@end menu
@end group
@end example

For example, to refer directly to the @samp{Outlining} and
@samp{Rebinding} nodes in the @cite{Emacs Manual}, you would write a
menu like this:@refill

@example
@group
@@menu
* Outlining: (emacs)Outline Mode. The major mode for
                                 editing outlines.
* Rebinding: (emacs)Rebinding.    How to redefine the
                                 meaning of a key.
@@end menu
@end group
@end example

If you do not list the node name, but only name the file, then Info
presumes that you are referring to the `Top' node.@refill

The @file{dir} file that contains the main menu for Info has menu
entries that list only file names.  These take you directly to the `Top'
nodes of each Info document.  (@xref{Installing an Info File}.)

@need 700
For example:

@example
@group
* Info: (info).         Documentation browsing system.
* Emacs: (emacs).       The extensible, self-documenting
                       text editor.
@end group
@end example

@noindent
(The @file{dir} top level directory for the Info system is an Info file,
not a Texinfo file, but a menu entry looks the same in both types of
file.)@refill

The GNU Emacs Texinfo mode menu updating commands only work with nodes
within the current buffer, so you cannot use them to create menus that
refer to other files.  You must write such menus by hand.


@node Cross References
@chapter Cross References
@cindex Making cross references
@cindex Cross references
@cindex References

@dfn{Cross references} are used to refer the reader to other parts of the
same or different Texinfo files.  In Texinfo, nodes and anchors are the
places to which cross references can refer.

@menu
* References::                  What cross references are for.
* Cross Reference Commands::    A summary of the different commands.
* Cross Reference Parts::       A cross reference has several parts.
* xref::                        Begin a reference with `See' @dots{}
* Top Node Naming::             How to refer to the beginning of another file.
* ref::                         A reference for the last part of a sentence.
* pxref::                       How to write a parenthetical cross reference.
* inforef::                     How to refer to an Info-only file.
* uref::                        How to refer to a uniform resource locator.
* cite::                        How to refer to books not in the Info system.
@end menu

@node References
@section What References Are For

Often, but not always, a printed document should be designed so that
it can be read sequentially.  People tire of flipping back and forth
to find information that should be presented to them as they need
it.@refill

However, in any document, some information will be too detailed for
the current context, or incidental to it; use cross references to
provide access to such information.  Also, an online help system or a
reference manual is not like a novel; few read such documents in
sequence from beginning to end.  Instead, people look up what they
need.  For this reason, such creations should contain many cross
references to help readers find other information that they may not
have read.@refill

In a printed manual, a cross reference results in a page reference,
unless it is to another manual altogether, in which case the cross
reference names that manual.@refill

In Info, a cross reference results in an entry that you can follow
using the Info @samp{f} command.  (@inforef{Help-Xref, Following
cross-references, info}.)

The various cross reference commands use nodes (or anchors,
@pxref{anchor,,@code{@@anchor}}) to define cross reference locations.
This is evident in Info, in which a cross reference takes you to the
specified location.  @TeX{} also uses nodes to define cross reference
locations, but the action is less obvious.  When @TeX{} generates a DVI
file, it records each node's page number and uses the page numbers in making
references.  Thus, if you are writing a manual that will only be
printed, and will not be used online, you must nonetheless write
@code{@@node} lines to name the places to which you make cross
references.@refill

@need 800
@node Cross Reference Commands
@comment  node-name,  next,  previous,  up
@section Different Cross Reference Commands
@cindex Different cross reference commands

There are four different cross reference commands:@refill

@table @code
@item @@xref
Used to start a sentence in the printed manual saying @w{`See @dots{}'}
or an Info cross-reference saying @samp{*Note @var{name}: @var{node}.}.

@item @@ref
Used within or, more often, at the end of a sentence; same as
@code{@@xref} for Info; produces just the reference in the printed
manual without a preceding `See'.@refill

@item @@pxref
Used within parentheses to make a reference that suits both an Info
file and a printed book.  Starts with a lower case `see' within the
printed manual. (@samp{p} is for `parenthesis'.)@refill

@item @@inforef
Used to make a reference to an Info file for which there is no printed
manual.@refill
@end table

@noindent
(The @code{@@cite} command is used to make references to books and
manuals for which there is no corresponding Info file and, therefore,
no node to which to point.   @xref{cite, , @code{@@cite}}.)@refill

@node Cross Reference Parts
@comment  node-name,  next,  previous,  up
@section Parts of a Cross Reference
@cindex Cross reference parts
@cindex Parts of a cross reference

A cross reference command requires only one argument, which is the
name of the node to which it refers.  But a cross reference command
may contain up to four additional arguments.  By using these
arguments, you can provide a cross reference name for Info, a topic
description or section title for the printed output, the name of a
different Info file, and the name of a different printed
manual.@refill

Here is a simple cross reference example:@refill

@example
@@xref@{Node name@}.
@end example

@noindent
which produces

@example
*Note Node name::.
@end example

@noindent
and

@quotation
See Section @var{nnn} [Node name], page @var{ppp}.
@end quotation

@need 700
Here is an example of a full five-part cross reference:@refill

@example
@group
@@xref@{Node name, Cross Reference Name, Particular Topic,
info-file-name, A Printed Manual@}, for details.
@end group
@end example

@noindent
which produces

@example
*Note Cross Reference Name: (info-file-name)Node name,
for details.
@end example

@noindent
in Info and

@quotation
See section ``Particular Topic'' in @i{A Printed Manual}, for details.
@end quotation

@noindent
in a printed book.

The five possible arguments for a cross reference are:@refill

@enumerate
@item
The node or anchor name (required).  This is the location to which the
cross reference takes you.  In a printed document, the location of the
node provides the page reference only for references within the same
document.@refill

@item
The cross reference name for the Info reference, if it is to be
different from the node name or the topic description.  If you
include this argument, it becomes the first part of the cross reference.
It is usually omitted; then the topic description (third argument) is
used if it was specified; if that was omitted as well, the node name
is used.

@item
A topic description or section name.  Often, this is the title of the
section.  This is used as the name of the reference in the printed
manual.  If omitted, the node name is used.@refill

@item
The name of the Info file in which the reference is located, if it is
different from the current file.  You need not include any @samp{.info}
suffix on the file name, since Info readers try appending it
automatically.

@item
The name of a printed manual from a different Texinfo file.@refill
@end enumerate

The template for a full five argument cross reference looks like
this:@refill

@example
@group
@@xref@{@var{node-name}, @var{cross-reference-name}, @var{title-or-topic},
@var{info-file-name}, @var{printed-manual-title}@}.
@end group
@end example

Cross references with one, two, three, four, and five arguments are
described separately following the description of @code{@@xref}.@refill

Write a node name in a cross reference in exactly the same way as in
the @code{@@node} line, including the same capitalization; otherwise, the
formatters may not find the reference.@refill

You can write cross reference commands within a paragraph, but note
how Info and @TeX{} format the output of each of the various commands:
write @code{@@xref} at the beginning of a sentence; write
@code{@@pxref} only within parentheses, and so on.@refill

@node xref
@comment  node-name,  next,  previous,  up
@section @code{@@xref}
@findex xref
@cindex Cross references using @code{@@xref}
@cindex References using @code{@@xref}

The @code{@@xref} command generates a cross reference for the
beginning of a sentence.  The Info formatting commands convert it into
an Info cross reference, which the Info @samp{f} command can use to
bring you directly to another node.  The @TeX{} typesetting commands
convert it into a page reference, or a reference to another book or
manual.@refill

@menu
* Reference Syntax::            What a reference looks like and requires.
* One Argument::                @code{@@xref} with one argument.
* Two Arguments::               @code{@@xref} with two arguments.
* Three Arguments::             @code{@@xref} with three arguments.
* Four and Five Arguments::     @code{@@xref} with four and five arguments.
@end menu

@node Reference Syntax
@subsection What a Reference Looks Like and Requires

Most often, an Info cross reference looks like this:@refill

@example
*Note @var{node-name}::.
@end example

@noindent
or like this

@example
*Note @var{cross-reference-name}: @var{node-name}.
@end example

@noindent
In @TeX{}, a cross reference looks like this:

@quotation
See Section @var{section-number} [@var{node-name}], page @var{page}.
@end quotation

@noindent
or like this

@quotation
See Section @var{section-number} [@var{title-or-topic}], page @var{page}.
@end quotation

The @code{@@xref} command does not generate a period or comma to end
the cross reference in either the Info file or the printed output.
You must write that period or comma yourself; otherwise, Info will not
recognize the end of the reference.  (The @code{@@pxref} command works
differently.  @xref{pxref, , @code{@@pxref}}.)@refill

@quotation Caution
A period or comma @strong{must} follow the closing
brace of an @code{@@xref}.  It is required to terminate the cross
reference.  This period or comma will appear in the output, both in
the Info file and in the printed manual.@refill
@end quotation

@code{@@xref} must refer to an Info node by name.  Use @code{@@node}
to define the node (@pxref{Writing a Node}).@refill

@code{@@xref} is followed by several arguments inside braces, separated by
commas.  Whitespace before and after these commas is ignored.@refill

A cross reference requires only the name of a node; but it may contain
up to four additional arguments.  Each of these variations produces a
cross reference that looks somewhat different.@refill

@quotation Note
Commas separate arguments in a cross reference;
avoid including them in the title or other part lest the formatters
mistake them for separators.@refill
@end quotation

@node One Argument
@subsection @code{@@xref} with One Argument

The simplest form of @code{@@xref} takes one argument, the name of
another node in the same Info file.    The Info formatters produce
output that the Info readers can use to jump to the reference; @TeX{}
produces output that specifies the page and section number for you.@refill

@need 700
@noindent
For example,

@example
@@xref@{Tropical Storms@}.
@end example

@noindent
produces

@example
*Note Tropical Storms::.
@end example

@noindent
and

@quotation
See Section 3.1 [Tropical Storms], page 24.
@end quotation

@noindent
(Note that in the preceding example the closing brace is followed by a
period.)@refill

You can write a clause after the cross reference, like this:@refill

@example
@@xref@{Tropical Storms@}, for more info.
@end example

@noindent
which produces

@example
*Note Tropical Storms::, for more info.
@end example

@noindent
and

@quotation
See Section 3.1 [Tropical Storms], page 24, for more info.
@end quotation

@noindent
(Note that in the preceding example the closing brace is followed by a
comma, and then by the clause, which is followed by a period.)@refill

@node Two Arguments
@subsection @code{@@xref} with Two Arguments

With two arguments, the second is used as the name of the Info cross
reference, while the first is still the name of the node to which the
cross reference points.@refill

@need 750
@noindent
The template is like this:

@example
@@xref@{@var{node-name}, @var{cross-reference-name}@}.
@end example

@need 700
@noindent
For example,

@example
@@xref@{Electrical Effects, Lightning@}.
@end example

@noindent
produces:

@example
*Note Lightning: Electrical Effects.
@end example

@noindent
and

@quotation
See Section 5.2 [Electrical Effects], page 57.
@end quotation

@noindent
(Note that in the preceding example the closing brace is followed by a
period; and that the node name is printed, not the cross reference name.)

You can write a clause after the cross reference, like this:@refill

@example
@@xref@{Electrical Effects, Lightning@}, for more info.
@end example

@noindent
which produces
@example
*Note Lightning: Electrical Effects, for more info.
@end example

@noindent
and

@quotation
See Section 5.2 [Electrical Effects], page 57, for more info.
@end quotation

@noindent
(Note that in the preceding example the closing brace is followed by a
comma, and then by the clause, which is followed by a period.)@refill

@node Three Arguments
@subsection @code{@@xref} with Three Arguments

A third argument replaces the node name in the @TeX{} output.  The third
argument should be the name of the section in the printed output, or
else state the topic discussed by that section.  Often, you will want to
use initial upper case letters so it will be easier to read when the
reference is printed.  Use a third argument when the node name is
unsuitable because of syntax or meaning.@refill

Remember to avoid placing a comma within the title or topic section of
a cross reference, or within any other section.  The formatters divide
cross references into arguments according to the commas; a comma
within a title or other section will divide it into two arguments.  In
a reference, you need to write a title such as ``Clouds, Mist, and
Fog'' without the commas.@refill

Also, remember to write a comma or period after the closing brace of an
@code{@@xref} to terminate the cross reference.  In the following
examples, a clause follows a terminating comma.@refill


@need 750
@noindent
The template is like this:

@example
@group
@@xref@{@var{node-name}, @var{cross-reference-name}, @var{title-or-topic}@}.
@end group
@end example

@need 700
@noindent
For example,

@example
@group
@@xref@{Electrical Effects, Lightning, Thunder and Lightning@},
for details.
@end group
@end example

@noindent
produces

@example
*Note Lightning: Electrical Effects, for details.
@end example

@noindent
and

@quotation
See Section 5.2 [Thunder and Lightning], page 57, for details.
@end quotation

If a third argument is given and the second one is empty, then the
third argument serves both.  (Note how two commas, side by side, mark
the empty second argument.)@refill

@example
@group
@@xref@{Electrical Effects, , Thunder and Lightning@},
for details.
@end group
@end example

@noindent
produces

@example
*Note Thunder and Lightning: Electrical Effects, for details.
@end example

@noindent
and

@quotation
See Section 5.2 [Thunder and Lightning], page 57, for details.
@end quotation

As a practical matter, it is often best to write cross references with
just the first argument if the node name and the section title are the
same, and with the first and third arguments if the node name and title
are different.@refill

Here are several examples from @cite{The GNU Awk User's Guide}:@refill

@smallexample
@@xref@{Sample Program@}.
@@xref@{Glossary@}.
@@xref@{Case-sensitivity, ,Case-sensitivity in Matching@}.
@@xref@{Close Output, , Closing Output Files and Pipes@},
  for more information.
@@xref@{Regexp, , Regular Expressions as Patterns@}.
@end smallexample

@node Four and Five Arguments
@subsection @code{@@xref} with Four and Five Arguments

In a cross reference, a fourth argument specifies the name of another
Info file, different from the file in which the reference appears, and
a fifth argument specifies its title as a printed manual.@refill

Remember that a comma or period must follow the closing brace of an
@code{@@xref} command to terminate the cross reference.  In the
following examples, a clause follows a terminating comma.@refill

@need 800
@noindent
The template is:

@example
@group
@@xref@{@var{node-name}, @var{cross-reference-name}, @var{title-or-topic},
@var{info-file-name}, @var{printed-manual-title}@}.
@end group
@end example

@need 700
@noindent
For example,

@example
@@xref@{Electrical Effects, Lightning, Thunder and Lightning,
weather, An Introduction to Meteorology@}, for details.
@end example

@noindent
produces

@example
*Note Lightning: (weather)Electrical Effects, for details.
@end example

@noindent
The name of the Info file is enclosed in parentheses and precedes
the name of the node.

@noindent
In a printed manual, the reference looks like this:@refill

@quotation
See section ``Thunder and Lightning'' in @i{An Introduction to
Meteorology}, for details.
@end quotation

@noindent
The title of the printed manual is typeset in italics; and the
reference lacks a page number since @TeX{} cannot know to which page a
reference refers when that reference is to another manual.@refill

Often, you will leave out the second argument when you use the long
version of @code{@@xref}.  In this case, the third argument, the topic
description, will be used as the cross reference name in Info.@refill

@noindent
The template looks like this:

@example
@@xref@{@var{node-name}, , @var{title-or-topic}, @var{info-file-name},
@var{printed-manual-title}@}, for details.
@end example

@noindent
which produces

@example
*Note @var{title-or-topic}: (@var{info-file-name})@var{node-name}, for details.
@end example

@noindent
and

@quotation
See section @var{title-or-topic} in @var{printed-manual-title}, for details.
@end quotation

@need 700
@noindent
For example,

@example
@@xref@{Electrical Effects, , Thunder and Lightning,
weather, An Introduction to Meteorology@}, for details.
@end example

@noindent
produces

@example
@group
*Note Thunder and Lightning: (weather)Electrical Effects,
for details.
@end group
@end example

@noindent
and

@quotation
See section ``Thunder and Lightning'' in @i{An Introduction to
Meteorology}, for details.
@end quotation

On rare occasions, you may want to refer to another Info file that
is within a single printed manual---when multiple Texinfo files are
incorporated into the same @TeX{} run but make separate Info files.
In this case, you need to specify only the fourth argument, and not
the fifth.@refill

@node Top Node Naming
@section Naming a `Top' Node
@cindex Naming a `Top' Node in references
@cindex @samp{@r{Top}} node naming for references

In a cross reference, you must always name a node.  This means that in
order to refer to a whole manual, you must identify the `Top' node by
writing it as the first argument to the @code{@@xref} command.  (This
is different from the way you write a menu entry; see @ref{Other Info
Files, , Referring to Other Info Files}.)  At the same time, to
provide a meaningful section topic or title in the printed cross
reference (instead of the word `Top'), you must write an appropriate
entry for the third argument to the @code{@@xref} command.
@refill

@noindent
Thus, to make a cross reference to @cite{The GNU Make Manual},
write:@refill

@example
@@xref@{Top, , Overview, make, The GNU Make Manual@}.
@end example

@noindent
which produces

@example
*Note Overview: (make)Top.
@end example

@noindent
and

@quotation
See section ``Overview'' in @i{The GNU Make Manual}.
@end quotation

@noindent
In this example, @samp{Top} is the name of the first node, and
@samp{Overview} is the name of the first section of the manual.


@node ref
@section @code{@@ref}
@cindex Cross references using @code{@@ref}
@cindex References using @code{@@ref}
@findex ref

@code{@@ref} is nearly the same as @code{@@xref} except that it does
not generate a `See' in the printed output, just the reference itself.
This makes it useful as the last part of a sentence.

@noindent For example,

@cindex Hurricanes
@example
For more information, @@pxref@{This@}, and @@ref@{That@}.
@end example

@noindent produces in Info:

@example
For more information, *note This::, and *note That::.
@end example

@noindent and in printed output:

@quotation
For more information, see Section 1.1 [This], page 1,
and Section 1.2 [That], page 2.
@end quotation

The @code{@@ref} command sometimes tempts writers to express
themselves in a manner that is suitable for a printed manual but looks
awkward in the Info format.  Bear in mind that your audience will be
using both the printed and the Info format.  For example:

@cindex Sea surges
@example
Sea surges are described in @@ref@{Hurricanes@}.
@end example

@noindent looks ok in the printed output:

@quotation
Sea surges are described in Section 6.7 [Hurricanes], page 72.
@end quotation

@noindent but is awkward to read in Info, ``note'' being a verb:

@example
Sea surges are described in *note Hurricanes::.
@end example

You should write a period or comma immediately after an @code{@@ref}
command with two or more arguments.  If there is no such following
punctuation, @command{makeinfo} will generate a (grammatically
incorrect) period in the Info output; otherwise, the cross-reference
would fail completely, due to the current syntax of Info format.

In general, it is best to use @code{@@ref} only when you need some
word other than ``see'' to precede the reference.  When ``see'' (or
``See'') is ok, @code{@@xref} and @code{@@pxref} are preferable.


@node pxref
@section @code{@@pxref}
@cindex Cross references using @code{@@pxref}
@cindex References using @code{@@pxref}
@findex pxref

The parenthetical reference command, @code{@@pxref}, is nearly the
same as @code{@@xref}, but it is best used at the end of a sentence or
before a closing parenthesis.  The command differs from @code{@@xref}
in two ways:

@enumerate
@item
@TeX{} typesets the reference for the printed manual with a lower case
`see' rather than an upper case `See'.

@item
The Info formatting commands automatically end the reference with a
closing colon or period, if necessary.
@end enumerate

@code{@@pxref} is designed so that the output looks right and works
right at the end of a sentence or parenthetical phrase, both in
printed output and in an Info file.  In a printed manual, a closing
comma or period should not follow a cross reference within
parentheses; such punctuation is wrong.  But in an Info file, suitable
closing punctuation must follow the cross reference so Info can
recognize its end.  @code{@@pxref} spares you the need to use
complicated methods to put a terminator into one form of the output
and not the other.

@noindent
With one argument, a parenthetical cross reference looks like this:

@cindex Flooding
@example
@dots{} storms cause flooding (@@pxref@{Hurricanes@}) @dots{}
@end example

@need 800
@noindent
which produces

@example
@group
@dots{} storms cause flooding (*note Hurricanes::) @dots{}
@end group
@end example

@noindent
and

@quotation
@dots{} storms cause flooding (see Section 6.7 [Hurricanes], page 72) @dots{}
@end quotation

With two arguments, a parenthetical cross reference has this template:

@example
@dots{} (@@pxref@{@var{node-name}, @var{cross-reference-name}@}) @dots{}
@end example

@noindent
which produces

@example
@dots{} (*note @var{cross-reference-name}: @var{node-name}.) @dots{}
@end example

@noindent
and

@quotation
@dots{} (see Section @var{nnn} [@var{node-name}], page @var{ppp}) @dots{}
@end quotation

@code{@@pxref} can be used with up to five arguments, just like
@code{@@xref} (@pxref{xref, , @code{@@xref}}).

In past versions of Texinfo, it was not allowed to write punctuation
after a @code{@@pxref}, so it could be used @emph{only} before a right
parenthesis.  This is no longer the case, so now it can be used (for
example) at the end of a sentence, where a lowercase ``see'' works
best.  For instance:

@example
@dots{} For more information, @@pxref@{More@}.
@end example

@noindent
which outputs (in Info):

@example
@dots{} For more information, *note More::.
@end example

@noindent
This works fine.  @code{@@pxref} should only be followed by a comma,
period, or right parenthesis; in other cases, @command{makeinfo} has
to insert a period to make the cross-reference work correctly in Info,
and that period looks wrong.

As a matter of general style, @code{@@pxref} is best used at the ends
of sentences.  Although it technically works in the middle of a
sentence, that location breaks up the flow of reading.


@node inforef
@section @code{@@inforef}
@cindex Cross references using @code{@@inforef}
@cindex References using @code{@@inforef}
@findex inforef

@code{@@inforef} is used for making cross references to Info
documents---even from a printed manual.  This might be because you
want to refer to conditional @code{@@ifinfo} text
(@pxref{Conditionals}), or because printed output is not available
(perhaps because there is no Texinfo source), among other
possibilities.

The command takes either two or three arguments, in the following
order:@refill

@enumerate
@item
The node name.

@item
The cross reference name (optional).

@item
The Info file name.
@end enumerate

@noindent
Separate the arguments with commas, as with @code{@@xref}.  Also, you
must terminate the reference with a comma or period after the
@samp{@}}, as you do with @code{@@xref}.@refill

@noindent
The template is:

@example
@@inforef@{@var{node-name}, @var{cross-reference-name}, @var{info-file-name}@},
@end example

@need 800
@noindent
For example,

@example
@group
@@inforef@{Advanced, Advanced Info commands, info@},
for more information.
@end group
@end example

@need 800
@noindent
produces (in Info):

@example
@group
*Note Advanced Info commands: (info)Advanced,
for more information.
@end group
@end example

@need 800
@noindent
and (in the printed output):

@quotation
See Info file @file{info}, node @samp{Advanced}, for more information.
@end quotation

(This particular example is not realistic, since the Info manual is
written in Texinfo, so all formats are available.)

The converse of @code{@@inforef} is @code{@@cite}, which is used to
refer to printed works for which no Info form exists.  @xref{cite, ,
@code{@@cite}}.


@node uref
@section @code{@@url}, @code{@@uref@{@var{url}[, @var{text}][, @var{replacement}]@}}
@findex uref
@cindex Uniform resource locator, referring to
@cindex URL, referring to

@cindex @code{href}, producing HTML
@code{@@uref} produces a reference to a uniform resource locator (url).
It takes one mandatory argument, the url, and two optional arguments
which control the text that is displayed.  In HTML output, @code{@@uref}
produces a link you can follow.

@code{@@url} is a synonym for @code{@@uref}.  Originally, @code{@@url}
had the meaning of @code{@@indicateurl}
(@pxref{indicateurl,,@code{@@indicateurl}}), but in actual practice it
was misused the vast majority of the time.  So we've changed the
meaning.

The second argument, if specified, is the text to display (the default
is the url itself); in Info and DVI output, but not in HTML output, the
url is also output.

@cindex Man page, reference to
The third argument, if specified, is the text to display, but in this
case the url is @emph{not} output in any format.  This is useful when
the text is already sufficiently referential, as in a man page.  If
the third argument is given, the second argument is ignored.

If the url is long enough to cause problems with line breaking, you
may find it useful to insert @code{@@/} at places where a line break
would be acceptable (after @samp{/} characters, for instance).  This
tells @TeX{} to allow (but not force) a line break at those places.
@xref{Line Breaks}.

Here is an example of the simple one argument form, where the url is
both the target and the text of the link:

@example
The official GNU ftp site is @@uref@{ftp://ftp.gnu.org/gnu@}.
@end example

@noindent produces:
@display
The official GNU ftp site is @uref{ftp://ftp.gnu.org/gnu}.
@end display


An example of the two-argument form:
@example
The official @@uref@{ftp://ftp.gnu.org/gnu, GNU ftp site@}
holds programs and texts.
@end example

@noindent produces:
@display
The official @uref{ftp://ftp.gnu.org/gnu, GNU ftp site}
holds programs and texts.
@end display

@noindent that is, the Info output is this:
@example
The official GNU ftp site (ftp://ftp.gnu.org/gnu)
holds programs and texts.
@end example

@noindent and the HTML output is this:
@example
The official <a href="ftp://ftp.gnu.org/gnu">GNU ftp site</a>
holds programs and texts.
@end example


An example of the three-argument form:
@example
The @@uref@{/man.cgi/1/ls,,ls@} program @dots{}
@end example

@noindent produces:
@display
The @uref{/man.cgi/1/ls,,ls} program @dots{}
@end display

@noindent but with HTML:
@example
The <a href="/man.cgi/1/ls">ls</a> program @dots{}
@end example

To merely indicate a url without creating a link people can follow, use
@code{@@indicateurl} (@pxref{indicateurl, @code{@@indicateurl}}).

Some people prefer to display url's in the unambiguous format:

@display
<URL:http://@var{host}/@var{path}>
@end display

@noindent
@cindex <URL: convention, not used
You can use this form in the input file if you wish.  We feel it's not
necessary to include the @samp{<URL:} and @samp{>} in the output,
since any software that tries to detect url's in text already has to
detect them without the @samp{<URL:} to be useful.


@node cite
@section @code{@@cite}@{@var{reference}@}
@findex cite

Use the @code{@@cite} command for the name of a book that lacks a
companion Info file.  The command produces italics in the printed
manual, and quotation marks in the Info file.

If a book is written in Texinfo, it is better to use a cross reference
command since a reader can easily follow such a reference in Info.
@xref{xref, , @code{@@xref}}.


@node Marking Text
@chapter Marking Words and Phrases
@cindex Paragraph, marking text within
@cindex Marking words and phrases
@cindex Words and phrases, marking them
@cindex Marking text within a paragraph
@cindex Text, marking up

In Texinfo, you can mark words and phrases in a variety of ways.
The Texinfo formatters use this information to determine how to
highlight the text.
You can specify, for example, whether a word or phrase is a
defining occurrence, a metasyntactic variable, or a symbol used in a
program.  Also, you can emphasize text, in several different ways.

@menu
* Indicating::                  How to indicate definitions, files, etc.
* Emphasis::                    How to emphasize text.
@end menu


@node Indicating
@section Indicating Definitions, Commands, etc.
@cindex Highlighting text
@cindex Indicating commands, definitions, etc.

Texinfo has commands for indicating just what kind of object a piece of
text refers to.  For example, metasyntactic variables are marked by
@code{@@var}, and code by @code{@@code}.  Since the pieces of text are
labelled by commands that tell what kind of object they are, it is easy
to change the way the Texinfo formatters prepare such text.  (Texinfo is
an @emph{intentional} formatting language rather than a @emph{typesetting}
formatting language.)@refill

For example, in a printed manual,
code is usually illustrated in a typewriter font;
@code{@@code} tells @TeX{} to typeset this text in this font.  But it
would be easy to change the way @TeX{} highlights code to use another
font, and this change would not affect how keystroke examples are
highlighted.  If straight typesetting commands were used in the body
of the file and you wanted to make a change, you would need to check
every single occurrence to make sure that you were changing code and
not something else that should not be changed.@refill

@menu
* Useful Highlighting::         Highlighting provides useful information.
* code::                        Indicating program code.
* kbd::                         Showing keyboard input.
* key::                         Specifying keys.
* samp::                        Indicating a literal sequence of characters.
* verb::                        Indicating a verbatim sequence of characters.
* var::                         Indicating metasyntactic variables.
* env::                         Indicating environment variables.
* file::                        Indicating file names.
* command::                     Indicating command names.
* option::                      Indicating option names.
* dfn::                         Specifying definitions.
* abbr::                        Indicating abbreviations.
* acronym::                     Indicating acronyms.
* indicateurl::                 Indicating an example URL.
* email::                       Indicating an electronic mail address.
@end menu


@node Useful Highlighting
@subsection Highlighting Commands are Useful

The highlighting commands can be used to extract useful information
from the file, such as lists of functions or file names.  It is
possible, for example, to write a program in Emacs Lisp (or a keyboard
macro) to insert an index entry after every paragraph that contains
words or phrases marked by a specified command.  You could do this to
construct an index of functions if you had not already made the
entries.@refill

The commands serve a variety of purposes:@refill

@table @code
@item @@code@{@var{sample-code}@}
Indicate text that is a literal example of a piece of a program.
@xref{code,,@code{@@code}}.

@item @@kbd@{@var{keyboard-characters}@}
Indicate keyboard input.
@xref{kbd,,@code{@@kbd}}.

@item @@key@{@var{key-name}@}
Indicate the conventional name for a key on a keyboard.
@xref{key,,@code{@@key}}.

@item @@samp@{@var{text}@}
Indicate text that is a literal example of a sequence of characters.
@xref{samp,,@code{@@samp}}.

@item @@verb@{@var{text}@}
Write a verbatim sequence of characters.
@xref{verb,,@code{@@verb}}.

@item @@var@{@var{metasyntactic-variable}@}
Indicate a metasyntactic variable.
@xref{var,,@code{@@var}}.

@item @@env@{@var{environment-variable}@}
Indicate an environment variable.
@xref{env,,@code{@@env}}.

@item @@file@{@var{file-name}@}
Indicate the name of a file.
@xref{file,,@code{@@file}}.

@item @@command@{@var{command-name}@}
Indicate the name of a command.
@xref{command,,@code{@@command}}.

@item @@option@{@var{option}@}
Indicate a command-line option.
@xref{option,,@code{@@option}}.

@item @@dfn@{@var{term}@}
Indicate the introductory or defining use of a term.
@xref{dfn,,@code{@@dfn}}.

@item @@cite@{@var{reference}@}
Indicate the name of a book.
@xref{cite,,@code{@@cite}}.

@item @@abbr@{@var{abbreviation}@}
Indicate an abbreviation, such as `Comput.'.

@item @@acronym@{@var{acronym}@}
Indicate an acronym.
@xref{acronym,,@code{@@acronym}}.

@item @@indicateurl@{@var{uniform-resource-locator}@}
Indicate an example (that is, nonfunctional) uniform resource locator.
@xref{indicateurl,,@code{@@indicateurl}}.  (Use @code{@@url}
(@pxref{uref,,@code{@@url}}) for live url's.)

@item @@email@{@var{email-address}[, @var{displayed-text}]@}
Indicate an electronic mail address.
@xref{email,,@code{@@email}}.

@ignore
@item @@ctrl@{@var{ctrl-char}@}
Use for an ASCII control character.
@end ignore
@end table


@node code
@subsection @code{@@code}@{@var{sample-code}@}
@findex code

@cindex Syntactic tokens, indicating
Use the @code{@@code} command to indicate text that is a piece of a
program and which consists of entire syntactic tokens.  Enclose the
text in braces.

@cindex Expressions in a program, indicating
@cindex Keywords, indicating
@cindex Reserved words, indicating
Thus, you should use @code{@@code} for an expression in a program, for
the name of a variable or function used in a program, or for a
keyword in a programming language.

Use @code{@@code} for command names in languages that resemble
programming languages, such as Texinfo.  For example, @code{@@code} and
@code{@@samp} are produced by writing @samp{@@code@{@@@@code@}} and
@samp{@@code@{@@@@samp@}} in the Texinfo source, respectively.

@cindex Case, not altering in @code{@@code}
It is incorrect to alter the case of a word inside an @code{@@code}
command when it appears at the beginning of a sentence.  Most computer
languages are case sensitive.  In C, for example, @code{Printf} is
different from the identifier @code{printf}, and most likely is a
misspelling of it.  Even in languages which are not case sensitive, it
is confusing to a human reader to see identifiers spelled in different
ways.  Pick one spelling and always use that.  If you do not want to
start a sentence with a command name written all in lower case, you
should rearrange the sentence.

In the printed manual, @code{@@code} causes @TeX{} to typeset the
argument in a typewriter face.  In the Info file, it causes the Info
formatting commands to use single quotation marks around the text.
For example,

@example
The function returns @@code@{nil@}.
@end example

@noindent
produces this:

@quotation
The function returns @code{nil}.
@end quotation

@iftex
@noindent
and this in the Info file:
@example
The function returns `nil'.
@end example
@end iftex

Here are some cases for which it is preferable @emph{not} to use @code{@@code}:

@itemize @bullet
@item
For shell command names such as @command{ls} (use @code{@@command}).

@item
For shell options such as @samp{-c} when such options stand alone (use
@code{@@option}).

@item
Also, an entire shell command often looks better if written using
@code{@@samp} rather than @code{@@code}.  In this case, the rule is to
choose the more pleasing format.

@item
For environment variable such as @env{TEXINPUTS} (use @code{@@env}).

@item
For a string of characters shorter than a syntactic token.  For example,
if you are writing about @samp{goto-ch}, which is just a part of the
name for the @code{goto-char} Emacs Lisp function, you should use
@code{@@samp}.

@item
In general, when writing about the characters used in a token; for
example, do not use @code{@@code} when you are explaining what letters
or printable symbols can be used in the names of functions.  (Use
@code{@@samp}.)  Also, you should not use @code{@@code} to mark text
that is considered input to programs unless the input is written in a
language that is like a programming language.  For example, you should
not use @code{@@code} for the keystroke commands of GNU Emacs (use
@code{@@kbd} instead) although you may use @code{@@code} for the names
of the Emacs Lisp functions that the keystroke commands invoke.

@end itemize

Since @code{@@command}, @code{@@option}, and @code{@@env} were
introduced relatively recently, it is acceptable to use @code{@@code} or
@code{@@samp} for command names, options, and environment variables.
The new commands allow you to express the markup more precisely, but
there is no real harm in using the older commands, and of course the
long-standing manuals do so.

Ordinarily, @TeX{} will consider breaking lines at @samp{-} and
@samp{_} characters within @code{@@code} and related commands.  This
can be controlled with @code{@@allowcodebreaks}
(@pxref{allowcodebreaks,,@code{@@allowcodebreaks}}).


@node kbd
@subsection @code{@@kbd}@{@var{keyboard-characters}@}
@findex kbd
@cindex Keyboard input

Use the @code{@@kbd} command for characters of input to be typed by
users.  For example, to refer to the characters @kbd{M-a}, write:

@example
@@kbd@{M-a@}
@end example

@noindent
and to refer to the characters @kbd{M-x shell}, write:

@example
@@kbd@{M-x shell@}
@end example

@cindex User input
@cindex Slanted typewriter font, for @code{@@kbd}
By default, the @code{@@kbd} command produces a different font
(slanted typewriter instead of normal typewriter) in the printed
manual, so users can distinguish the characters that they are supposed
to type from those that the computer outputs.

In Info output, @code{@@kbd} is usually the same as @code{@@code},
producing `quotes' around its argument.  However, in typewriter-like
contexts such as the @code{@@example} environment (@pxref{example})
and @code{@@code} command itself, the quotes are omitted, since Info
format cannot use distinguishing fonts.

@findex kbdinputstyle
Since the usage of @code{@@kbd} varies from manual to manual, you can
control the font switching with the @code{@@kbdinputstyle} command.
This command has no effect on Info output.  Write this command at the
beginning of a line with a single word as an argument, one of the
following:

@vindex distinct@r{, value for @code{@@kbdinputstyle}}
@vindex example@r{, value for @code{@@kbdinputstyle}}
@vindex code@r{, value for @code{@@kbdinputstyle}}
@table @samp
@item code
Always use the same font for @code{@@kbd} as @code{@@code}.
@item example
Use the distinguishing font for @code{@@kbd} only in @code{@@example}
and similar environments.
@item distinct
(the default) Always use the distinguishing font for @code{@@kbd}.
@end table

You can embed another @@-command inside the braces of an @code{@@kbd}
command.  Here, for example, is the way to describe a command that
would be described more verbosely as ``press the @samp{r} key and then
press the @key{RETURN} key'':

@example
@@kbd@{r @@key@{RET@}@}
@end example

@noindent
This produces: @kbd{r @key{RET}}.  (The present manual uses the
default for @code{@@kbdinputstyle}.)

You also use the @code{@@kbd} command if you are spelling out the letters
you type; for example:

@example
To give the @@code@{logout@} command,
type the characters @@kbd@{l o g o u t @@key@{RET@}@}.
@end example

@noindent
This produces:

@quotation
To give the @code{logout} command,
type the characters @kbd{l o g o u t @key{RET}}.
@end quotation

(Also, this example shows that you can add spaces for clarity.  If you
explicitly want to mention a space character as one of the characters of
input, write @kbd{@@key@{SPC@}} for it.)@refill


@node key
@subsection @code{@@key}@{@var{key-name}@}
@findex key

Use the @code{@@key} command for the conventional name for a key on a
keyboard, as in:@refill

@example
@@key@{RET@}
@end example

You can use the @code{@@key} command within the argument of an
@code{@@kbd} command when the sequence of characters to be typed
includes one or more keys that are described by name.@refill

For example, to produce @kbd{C-x @key{ESC}} and @kbd{M-@key{TAB}} you
would type:

@example
@@kbd@{C-x @@key@{ESC@}@}
@@kbd@{M-@@key@{TAB@}@}
@end example

Here is a list of the recommended names for keys:
@cindex Recommended names for keys
@cindex Keys, recommended names
@cindex Names recommended for keys
@cindex Abbreviations for keys

@quotation
@table @t
@item SPC
Space
@item RET
Return
@item LFD
Linefeed (however, since most keyboards nowadays do not have a Linefeed key,
it might be better to call this character @kbd{C-j})
@item TAB
Tab
@item BS
Backspace
@item ESC
Escape
@item DELETE
Delete
@item SHIFT
Shift
@item CTRL
Control
@item META
Meta
@end table
@end quotation

@cindex META key
There are subtleties to handling words like `meta' or `ctrl' that are
names of modifier keys.  When mentioning a character in which the
modifier key is used, such as @kbd{Meta-a}, use the @code{@@kbd} command
alone; do not use the @code{@@key} command; but when you are referring
to the modifier key in isolation, use the @code{@@key} command.  For
example, write @samp{@@kbd@{Meta-a@}} to produce @kbd{Meta-a} and
@samp{@@key@{META@}} to produce @key{META}.

As a convention in GNU manuals, @code{@@key} should not be used in
index entries.


@node samp
@subsection @code{@@samp}@{@var{text}@}
@findex samp

Use the @code{@@samp} command to indicate text that is a literal example
or `sample' of a sequence of characters in a file, string, pattern, etc.
Enclose the text in braces.  The argument appears within single
quotation marks in both the Info file and the printed manual; in
addition, it is printed in a fixed-width font.@refill

@example
To match @@samp@{foo@} at the end of the line,
use the regexp @@samp@{foo$@}.
@end example

@noindent
produces

@quotation
To match @samp{foo} at the end of the line, use the regexp
@samp{foo$}.@refill
@end quotation

Any time you are referring to single characters, you should use
@code{@@samp} unless @code{@@kbd} or @code{@@key} is more appropriate.
Also, you may use @code{@@samp} for entire statements in C and for entire
shell commands---in this case, @code{@@samp} often looks better than
@code{@@code}.  Basically, @code{@@samp} is a catchall for whatever is
not covered by @code{@@code}, @code{@@kbd}, or @code{@@key}.@refill

Only include punctuation marks within braces if they are part of the
string you are specifying.  Write punctuation marks outside the braces
if those punctuation marks are part of the English text that surrounds
the string.  In the following sentence, for example, the commas and
period are outside of the braces:@refill

@example
@group
In English, the vowels are @@samp@{a@}, @@samp@{e@},
@@samp@{i@}, @@samp@{o@}, @@samp@{u@}, and sometimes
@@samp@{y@}.
@end group
@end example

@noindent
This produces:

@quotation
In English, the vowels are @samp{a}, @samp{e},
@samp{i}, @samp{o}, @samp{u},  and sometimes
@samp{y}.
@end quotation


@node verb
@subsection @code{@@verb}@{<char>@var{text}<char>@}
@findex verb
@cindex Verbatim in-line text

@cindex Delimiter character, for verbatim
Use the @code{@@verb} command to print a verbatim sequence of
characters.

Like @LaTeX{}'s @code{\verb} command, the verbatim text can be quoted using
any unique delimiter character.  Enclose the verbatim text, including the
delimiters, in braces.  Text is printed in a fixed-width font:

@example
How many @@verb@{|@@|@}-escapes does one need to print this
@@verb@{.@@a @@b @@c.@} string or @@verb@{+@@'e@?`@!`@{@}\+@} this?
@end example

@noindent
produces

@example
How many @verb{|@|}-escapes does one need to print this
@verb{.@a @b @c.} string or these @verb{+@'e?`{}!`\+} this?
@end example

This is in contrast to @code{@@samp} (see the previous section),
@code{@@code}, and similar commands; in those cases, the argument is
normal Texinfo text, where the three characters @code{@@@{@}} are
special.  With @code{@@verb}, nothing is special except the delimiter
character you choose.

It is not reliable to use @code{@@verb} inside other Texinfo
constructs.  In particular, it does not work to use @code{@@verb} in
anything related to cross-referencing, such as section titles or
figure captions.


@node var
@subsection @code{@@var}@{@var{metasyntactic-variable}@}
@findex var

Use the @code{@@var} command to indicate metasyntactic variables.  A
@dfn{metasyntactic variable} is something that stands for another piece of
text.  For example, you should use a metasyntactic variable in the
documentation of a function to describe the arguments that are passed
to that function.@refill

Do not use @code{@@var} for the names of particular variables in
programming languages.  These are specific names from a program, so
@code{@@code} is correct for them (@pxref{code}).  For example, the
Emacs Lisp variable @code{texinfo-tex-command} is not a metasyntactic
variable; it is properly formatted using @code{@@code}.

Do not use @code{@@var} for environment variables either; @code{@@env}
is correct for them (see the next section).

The effect of @code{@@var} in the Info file is to change the case of the
argument to all upper case.  In the printed manual and HTML output, the
argument is printed in slanted type.

@need 700
For example,

@example
To delete file @@var@{filename@},
type @@samp@{rm @@var@{filename@}@}.
@end example

@noindent
produces

@quotation
To delete file @var{filename}, type @samp{rm @var{filename}}.
@end quotation

@noindent
(Note that @code{@@var} may appear inside @code{@@code},
@code{@@samp}, @code{@@file}, etc.)@refill

Write a metasyntactic variable all in lower case without spaces, and
use hyphens to make it more readable.  Thus, the Texinfo source for
the illustration of how to begin a Texinfo manual looks like
this:@refill

@example
@group
\input texinfo
@@@@setfilename @@var@{info-file-name@}
@@@@settitle @@var@{name-of-manual@}
@end group
@end example

@noindent
This produces:

@example
@group
\input texinfo
@@setfilename @var{info-file-name}
@@settitle @var{name-of-manual}
@end group
@end example

In some documentation styles, metasyntactic variables are shown with
angle brackets, for example:@refill

@example
@dots{}, type rm <filename>
@end example

@noindent
However, that is not the style that Texinfo uses.  (You can, of
course, modify the sources to @file{texinfo.tex} and the Info formatting commands
to output the @code{<@dots{}>} format if you wish.)@refill


@node env
@subsection @code{@@env}@{@var{environment-variable}@}
@findex env

Use the @code{@@env} command to indicate environment variables, as used
by many operating systems, including GNU.  Do not use it for
metasyntactic variables; use @code{@@var} instead (see the previous
section).

@code{@@env} is equivalent to @code{@@code} in its effects.
For example:

@example
The @@env@{PATH@} environment variable @dots{}
@end example
@noindent produces
@quotation
The @env{PATH} environment variable @dots{}
@end quotation


@node file
@subsection @code{@@file}@{@var{file-name}@}
@findex file

Use the @code{@@file} command to indicate text that is the name of a
file, buffer, or directory, or is the name of a node in Info.  You can
also use the command for file name suffixes.  Do not use @code{@@file}
for symbols in a programming language; use @code{@@code}.

Currently, @code{@@file} is equivalent to @code{@@samp} in its effects.
For example,@refill

@example
The @@file@{.el@} files are in
the @@file@{/usr/local/emacs/lisp@} directory.
@end example

@noindent
produces

@quotation
The @file{.el} files are in
the @file{/usr/local/emacs/lisp} directory.
@end quotation


@node command
@subsection @code{@@command}@{@var{command-name}@}
@findex command
@cindex Command names, indicating
@cindex Program names, indicating

Use the @code{@@commannd} command to indicate command names, such as
@command{ls} or @command{cc}.

@code{@@command} is equivalent to @code{@@code} in its effects.
For example:

@example
The command @@command@{ls@} lists directory contents.
@end example
@noindent produces
@quotation
The command @command{ls} lists directory contents.
@end quotation

You should write the name of a program in the ordinary text font, rather
than using @code{@@command}, if you regard it as a new English word,
such as `Emacs' or `Bison'.

When writing an entire shell command invocation, as in @samp{ls -l},
you should use either @code{@@samp} or @code{@@code} at your discretion.


@node option
@subsection @code{@@option}@{@var{option-name}@}
@findex option

Use the @code{@@option} command to indicate a command-line option; for
example, @option{-l} or @option{--version} or
@option{--output=@var{filename}}.

@code{@@option} is equivalent to @code{@@samp} in its effects.
For example:

@example
The option @@option@{-l@} produces a long listing.
@end example
@noindent produces
@quotation
The option @option{-l} produces a long listing.
@end quotation

In tables, putting options inside @code{@@code} produces a
more pleasing effect.

@node dfn
@comment  node-name,  next,  previous,  up
@subsection @code{@@dfn}@{@var{term}@}
@findex dfn

Use the @code{@@dfn} command to identify the introductory or defining
use of a technical term.  Use the command only in passages whose
purpose is to introduce a term which will be used again or which the
reader ought to know.  Mere passing mention of a term for the first
time does not deserve @code{@@dfn}.  The command generates italics in
the printed manual, and double quotation marks in the Info file.  For
example:@refill

@example
Getting rid of a file is called @@dfn@{deleting@} it.
@end example

@noindent
produces

@quotation
Getting rid of a file is called @dfn{deleting} it.
@end quotation

As a general rule, a sentence containing the defining occurrence of a
term should be a definition of the term.  The sentence does not need
to say explicitly that it is a definition, but it should contain the
information of a definition---it should make the meaning clear.

@ignore
@c node ctrl, , cite, Indicating
@comment  node-name,  next,  previous,  up
@c subsection @code{@@ctrl}@{@var{ctrl-char}@}
@findex ctrl

The @code{@@ctrl} command is seldom used.  It describes an ASCII
control character by inserting the actual character into the Info
file.

Usually, in Texinfo, you talk what you type as keyboard entry by
describing it with @code{@@kbd}: thus, @samp{@@kbd@{C-a@}} for
@kbd{C-a}.  Use @code{@@kbd} in this way when talking about a control
character that is typed on the keyboard by the user.  When talking
about a control character appearing in a file or a string, do not use
@code{@@kbd} since the control character is not typed.  Also, do not
use @samp{C-} but spell out @code{control-}, as in @samp{control-a},
to make it easier for a reader to understand.@refill

@code{@@ctrl} is an idea from the beginnings of Texinfo which may not
really fit in to the scheme of things.  But there may be times when
you want to use the command.  The pattern is
@code{@@ctrl@{@var{ch}@}}, where @var{ch} is an ASCII character
whose control-equivalent is wanted.  For example, to specify
@samp{control-f}, you would enter@refill

@example
@@ctrl@{f@}
@end example

@noindent
produces

@quotation
@ctrl{f}
@end quotation

In the Info file, this generates the specified control character, output
literally into the file.  This is done so a user can copy the specified
control character (along with whatever else he or she wants) into another
Emacs buffer and use it.  Since the `control-h',`control-i', and
`control-j' characters are formatting characters, they should not be
indicated with @code{@@ctrl}.@refill

In a printed manual, @code{@@ctrl} generates text to describe or
identify that control character: an uparrow followed by the character
@var{ch}.@refill
@end ignore


@node abbr
@subsection @code{@@abbr}@{@var{abbreviation}[, @var{meaning}]@}
@findex abbr

@cindex Abbreviations, tagging
You can use the @code{@@abbr} command for general abbreviations.  The
abbreviation is given as the single argument in braces, as in
@samp{@@abbr@{Comput.@}}.  As a matter of style, or for particular
abbreviations, you may prefer to omit periods, as in
@samp{@@abbr@{Mr@} Stallman}.

@code{@@abbr} accepts an optional second argument, intended to be used
for the meaning of the abbreviation.

If the abbreviation ends with a lowercase letter and a period, and is
not at the end of a sentence, and has no second argument, remember to
use the @code{@@.} command (@pxref{Not Ending a
Sentence}) to get the correct spacing.  However, you do not have to
use @code{@@.} within the abbreviation itself; Texinfo automatically
assumes periods within the abbreviation do not end a sentence.

@cindex <abbr> and <abbrev> tags
In @TeX{} and in the Info output, the first argument is printed as-is;
if the second argument is present, it is printed in parentheses after
the abbreviation.  In HTML and XML, the @code{<abbr>} tag is
used; in Docbook, the @code{<abbrev>} tag is used.  For instance:

@example
@@abbr@{Comput. J., Computer Journal@}
@end example

@noindent produces:

@display
@abbr{Comput. J., Computer Journal}
@end display

For abbreviations consisting of all capital letters, you may prefer to
use the @code{@@acronym} command instead.  See the next section for
more on the usage of these two commands.


@node acronym
@subsection @code{@@acronym}@{@var{acronym}[, @var{meaning}]@}
@findex acronym

@cindex NASA, as acronym
@cindex Acronyms, tagging
Use the @code{@@acronym} command for abbreviations written in all
capital letters, such as `@acronym{NASA}'.  The abbreviation is given as
the single argument in braces, as in @samp{@@acronym@{NASA@}}.  As
a matter of style, or for particular acronyms, you may prefer to
use periods, as in @samp{@@acronym@{N.A.S.A.@}}.

@code{@@acronym} accepts an optional second argument, intended to be
used for the meaning of the acronym.

If the acronym is at the end of a sentence, and if there is no second
argument, remember to use the @code{@@.} or similar command
(@pxref{Ending a Sentence}) to get the correct spacing.

@cindex <acronym> tag
In @TeX{}, the acronym is printed in slightly smaller font.  In the
Info output, the argument is printed as-is.  In either format, if the
second argument is present, it is printed in parentheses after the
acronym.  In HTML, Docbook, and XML, the @code{<acronym>} tag is
used.  

For instance (since GNU is a recursive acronym, we use
@code{@@acronym} recursively):

@example
@@acronym@{GNU, @@acronym@{GNU@}'s Not Unix@}
@end example

@noindent produces:

@display
@acronym{GNU, @acronym{GNU}'s Not Unix}
@end display

@cindex Family names, in all capitals
In some circumstances, it is conventional to print family names in all
capitals.  Don't use @code{@@acronym} for this, since a name is not an
acronym.  Use @code{@@sc} instead (@pxref{Smallcaps}).

@code{@@abbr} and @code{@@acronym} are closely related commands: they
both signal to the reader that a shortened form is being used, and
possibly give a meaning.  When choosing whether to use these two
commands, please bear the following in mind.

@itemize @minus
@item
In standard English usage, acronyms are a subset of abbreviations:
they include pronounceable words like `@acronym{NATO}', `radar', and
`snafu', and some sources also include syllable acronyms like
`Usenet', hybrids like `@acronym{SIGGRAPH}', and unpronounceable
initialisms like `@acronym{FBI}'.

@item
In Texinfo, an acronym (but not an abbreviation) should consist only
of capital letters and periods, no lowercase.

@item
In @TeX{}, an acronym (but not an abbreviation) is printed in a
slightly smaller font.

@item
Some browsers place a dotted bottom border under abbreviations but not
acronyms.

@item
It's not essential to use either of these commands for all
abbreviations; use your judgment.  Text is perfectly readable without
them.

@end itemize


@node indicateurl
@subsection @code{@@indicateurl}@{@var{uniform-resource-locator}@}
@findex indicateurl
@cindex Uniform resource locator, indicating
@cindex URL, indicating

Use the @code{@@indicateurl} command to indicate a uniform resource
locator on the World Wide Web.  This is analogous to @code{@@file},
@code{@@var}, etc., and is purely for markup purposes.  It does not
produce a link you can follow in HTML output (use the @code{@@uref}
command for that, @pxref{uref,, @code{@@uref}}).  It is useful for
url's which do not actually exist.  For example:

@example
For example, the url might be @@indicateurl@{http://example.org/path@}.
@end example

@noindent which produces:

@display
For example, the url might be @indicateurl{http://example.org/path}.
@end display


@node email
@subsection @code{@@email}@{@var{email-address}[, @var{displayed-text}]@}
@findex email

Use the @code{@@email} command to indicate an electronic mail address.
It takes one mandatory argument, the address, and one optional argument, the
text to display (the default is the address itself).

@cindex Mailto link
In Info, the address is shown in angle brackets, preceded by the text
to display if any.  In @TeX{}, the angle brackets are omitted.  In
HTML output, @code{@@email} produces a @samp{mailto} link that usually
brings up a mail composition window.  For example:

@example
Send bug reports to @@email@{bug-texinfo@@@@gnu.org@},
suggestions to the @@email@{bug-texinfo@@@@gnu.org, same place@}.
@end example
@noindent produces
@display
Send bug reports to @email{bug-texinfo@@gnu.org},
suggestions to the @email{bug-texinfo@@gnu.org, same place}.
@end display


@node Emphasis
@section Emphasizing Text
@cindex Emphasizing text

Usually, Texinfo changes the font to mark words in the text according to
what category the words belong to; an example is the @code{@@code} command.
Most often, this is the best way to mark words.
However, sometimes you will want to emphasize text without indicating a
category.  Texinfo has two commands to do this.  Also, Texinfo has
several commands that specify the font in which @TeX{} will typeset
text.  These commands have no effect on Info and only one of them,
the @code{@@r} command, has any regular use.@refill

@menu
* emph & strong::               How to emphasize text in Texinfo.
* Smallcaps::                   How to use the small caps font.
* Fonts::                       Various font commands for printed output.
@end menu

@node emph & strong
@subsection @code{@@emph}@{@var{text}@} and @code{@@strong}@{@var{text}@}
@cindex Emphasizing text, font for
@findex emph
@findex strong

The @code{@@emph} and @code{@@strong} commands are for emphasis;
@code{@@strong} is stronger.  In printed output, @code{@@emph} produces
@emph{italics} and @code{@@strong} produces @strong{bold}.

For example,

@example
@group
@@strong@{Caution:@} @@samp@{rm * .[^.]*@}
removes @@emph@{all@} files in the directory.
@end group
@end example

@noindent
produces the following in printed output and HTML:

@quotation
@strong{Caution}: @samp{rm * .[^.]*}
removes @emph{all} files in the directory.
@end quotation

@noindent
and the following in Info:

@example
*Caution:* `rm * .[^.]*' removes _all_
files in the directory.
@end example

The @code{@@strong} command is seldom used except to mark what is, in
effect, a typographical element, such as the word `Caution' in the
preceding example.

In the Info output, @code{@@emph} surrounds the text with underscores
(@samp{_}), and @code{@@strong} puts asterisks around the text.

@quotation Caution
Do not use @code{@@strong} with the word @samp{Note}; Info will
mistake the combination for a cross reference.  (It's usually
redundant, anyway.)  Use a phrase such as @strong{Please notice} or
@strong{Caution} instead, or the optional argument to
@code{@@quotation}---@samp{Note} is allowable there.
@end quotation


@node Smallcaps
@subsection @code{@@sc}@{@var{text}@}: The Small Caps Font
@cindex Small caps font
@findex sc @r{(small caps font)}

Use the @samp{@@sc} command to set text in @sc{a small caps font}
(where possible).  Write the text you want to be in small caps between
braces in lower case, like this:

@example
Richard @@sc@{Stallman@} founded @@acronym@{GNU@}.
@end example

@noindent
This produces:

@display
Richard @sc{Stallman} founded @acronym{GNU}.
@end display

As shown here, we recommend using @code{@@acronym} for actual
acronyms (@pxref{acronym}), and reserving @code{@@sc} for special
cases where you want small caps.  The output is not the same
(@code{@@acronym} prints in a smaller text font, not the small caps
font), but more importantly it describes the actual text more
accurately.

Family names are one case where small capitals are sometimes desirable,
also as shown here.

@cindex <small> tag
@TeX{} typesets any uppercase letters between the braces of an
@code{@@sc} command in full-size capitals; only lowercase letters are
printed in the small caps font.  In the Info output, the argument to
@code{@@sc} is printed in all upper case.  In HTML, the argument is
uppercased and the output marked with the @code{<small>} tag to reduce
the font size.

Since it's redundant to mark all-uppercase text with @code{@@sc},
@command{makeinfo} warns about such usage.

We recommend using regular mixed case wherever possible.


@node Fonts
@subsection Fonts for Printing, Not Info
@cindex Fonts for printing, not Info

@findex fonttextsize
@cindex Font size, reducing
@cindex Reducing font size
@cindex Smaller fonts
Texinfo provides one command to change the size of the main body font
in the @TeX{} output for a document: @code{@@fonttextsize}.  It has no
effect at all in other output.  It takes a single argument on the
remainder of the line, which must be either @samp{10} or @samp{11}.
For example:

@example
@@fonttextsize 10
@end example

@cindex Printing cost, reducing
The effect is to reduce the body font to a 10@dmn{pt} size (the
default is 11@dmn{pt}).  Fonts for other elements, such as sections
and chapters, are reduced accordingly.  This should only be used in
conjunction with @code{@@smallbook} (@pxref{smallbook,,Printing
``Small'' Books}) or similar, since 10@dmn{pt} fonts on standard paper
(8.5x11 or A4) are too small.  One reason to use this command is to
save pages, and hence printing cost, for physical books.

Texinfo does not at present have commands to switch the font family
to use, or more general size-changing commands.

@cindex Styles, font
Texinfo also provides a number of font commands that specify font changes
in the printed manual and (where possible) in the HTML output, but
have no effect in the Info file.  All the commands apply to an
argument that follows, surrounded by braces.

@table @code
@item @@b
@findex b @r{(bold font)}
@cindex Bold font
selects @b{bold} face;

@item @@i
@findex i @r{(italic font)}
@cindex Italic font
selects an @i{italic} font;

@item @@r
@findex r @r{(roman font)}
@cindex Roman font
@cindex Default font
selects a @r{roman} font, which is the usual font in which text is
printed.  It may or may not be seriffed.

@item @@sansserif
@findex sansserif @r{(sans serif font)}
@cindex Sans serif font
selects a @sansserif{sans serif} font;

@item @@slanted
@findex slanted @r{(slanted font)}
@cindex Slanted font
@cindex Oblique font
selects a @slanted{slanted} font;

@item @@t
@findex t @r{(typewriter font)}
@cindex Monospace font
@cindex Fixed-width font
@cindex Typewriter font
selects the @t{fixed-width}, typewriter-style font used by @code{@@code};

@end table

(The commands with longer names were invented much later than the
others, at which time it did not seem desirable to use very short
names for such an infrequently needed feature.)

@cindex <lineannotation> Docbook tag
Only the @code{@@r} command has much use: in example-like
environments, you can use the @code{@@r} command to write comments in
the standard roman font instead of the fixed-width font.  This looks
better in printed output, and produces a @code{<lineannotation>} tag
in Docbook output.

For example,

@example
@group
@@lisp
(+ 2 2)    ; @@r@{Add two plus two.@}
@@end lisp
@end group
@end example

@noindent
produces

@lisp
(+ 2 2)    ; @r{Add two plus two.}
@end lisp

In general, you should avoid using the other font commands.  Some of
them are only useful when documenting functionality of specific font
effects, such as in @TeX{} and related packages.


@node Quotations and Examples
@chapter Quotations and Examples

Quotations and examples are blocks of text consisting of one or more
whole paragraphs that are set off from the bulk of the text and
treated differently.  They are usually indented in the output.

@findex end
In Texinfo, you always begin a quotation or example by writing an
@@-command at the beginning of a line by itself, and end it by writing
an @code{@@end} command that is also at the beginning of a line by
itself.  For instance, you begin an example by writing @code{@@example}
by itself at the beginning of a line and end the example by writing
@code{@@end example} on a line by itself, at the beginning of that
line, and with only one space between the @code{@@end} and the
@code{example}.

@menu
* Block Enclosing Commands::    Different constructs for different purposes.
* quotation::                   Writing a quotation.
* example::                     Writing an example in a fixed-width font.
* verbatim::                    Writing a verbatim example.
* verbatiminclude::             Including a file verbatim.
* lisp::                        Illustrating Lisp code.
* small::                       Examples in a smaller font.
* display::                     Writing an example in the current font.
* format::                      Writing an example without narrowed margins.
* exdent::                      Undo indentation on a line.
* flushleft & flushright::      Pushing text flush left or flush right.
* noindent::                    Preventing paragraph indentation.
* indent::                      Forcing paragraph indentation.
* cartouche::                   Drawing rounded rectangles around examples.
@end menu


@node Block Enclosing Commands
@section Block Enclosing Commands

Here are commands for quotations and examples, explained further in the
following sections:

@table @code
@item @@quotation
Indicate text that is quoted. The text is filled, indented (from both
margins), and printed in a roman font by default.

@item @@example
Illustrate code, commands, and the like. The text is printed
in a fixed-width font, and indented but not filled.

@item @@verbatim
Mark a piece of text that is to be printed verbatim; no character
substitutions are made and all commands are ignored, until the next
@code{@@end verbatim}.  The text is printed in a fixed-width font,
and not indented or filled.  Extra spaces and blank lines are
significant, and tabs are expanded.

@item @@smallexample
Same as @code{@@example}, except that in @TeX{} this command typesets
text in a smaller font.

@item @@lisp
Like @code{@@example}, but specifically for illustrating Lisp code. The
text is printed in a fixed-width font, and indented but not filled.

@item @@smalllisp
Is to @code{@@lisp} as @code{@@smallexample} is to @code{@@example}.

@item @@display
Display illustrative text.  The text is indented but not filled, and
no font is selected (so, by default, the font is roman).@refill

@item @@smalldisplay
Is to @code{@@display} as @code{@@smallexample} is to @code{@@example}.

@item @@format
Like @code{@@display} (the text is not filled and no font is selected),
but the text is not indented.

@item @@smallformat
Is to @code{@@format} as @code{@@smallexample} is to @code{@@example}.
@end table

The @code{@@exdent} command is used within the above constructs to
undo the indentation of a line.

The @code{@@flushleft} and @code{@@flushright} commands are used to line
up the left or right margins of unfilled text.@refill

The @code{@@noindent} command may be used after one of the above
constructs to prevent the following text from being indented as a new
paragraph.

You can use the @code{@@cartouche} environment around one of the above
constructs to highlight the example or quotation by drawing a box with
rounded corners around it.  @xref{cartouche, , Drawing Cartouches Around
Examples}.


@node quotation
@section @code{@@quotation}: Block quotations
@cindex Quotations
@findex quotation

The text of a quotation is processed normally (regular font, text is
filled) except that:

@itemize @bullet
@item
the margins are closer to the center of the page, so the whole of the
quotation is indented;

@item
and the first lines of paragraphs are indented no more than other lines.

@end itemize

@quotation
This is an example of text written between an @code{@@quotation}
command and an @code{@@end quotation} command.  An @code{@@quotation}
command is most often used to indicate text that is excerpted from
another (real or hypothetical) printed work.
@end quotation

Write an @code{@@quotation} command as text on a line by itself.  This
line will disappear from the output.  Mark the end of the quotation
with a line beginning with and containing only @code{@@end quotation}.
The @code{@@end quotation} line will likewise disappear from the
output.

@code{@@quotation} takes one optional argument, given on the remainder
of the line.  This text, if present, is included at the beginning of
the quotation in bold or otherwise emphasized, and followed with a
@samp{:}.  For example:

@example
@@quotation Note
This is
a foo.
@@end quotation
@end example

@noindent
produces

@quotation Note
This is
a foo.
@end quotation

If the @code{@@quotation} argument is exactly one of these words:

@example
Caution  Important  Note  Tip  Warning
@end example

@cindex <note> Docbook tag
@cindex <blockquote> HTML tag
@noindent then the Docbook output uses corresponding special tags
(@code{<note>}, etc.) instead of the default @code{<blockquote>}.
HTML output always uses @code{<blockquote>}.


@node example
@section @code{@@example}: Example Text
@cindex Examples, formatting them
@cindex Formatting examples
@findex example

The @code{@@example} environment is used to indicate an example that
is not part of the running text, such as computer input or output.
Write an @code{@@example} command at the beginning of a line by
itself.  Mark the end of the example with an @code{@@end example}
command, also written at the beginning of a line by itself.

An @code{@@example} environment has the following characteristics:

@itemize
@item Each line in the input file is a line in the output; that is,
the source text is not filled as it normally is.
@item Extra spaces and blank lines are significant.
@item The output is indented.
@item The output uses a fixed-width font.
@item Texinfo commands @emph{are} expanded; if you want the output to
be the input verbatim, use the @code{@@verbatim} environment instead
(@pxref{verbatim,,@code{@@verbatim}}).
@end itemize

For example,

@example
@@example
cp foo @@var@{dest1@}; \
 cp foo @@var@{dest2@}
@@end example
@end example

@noindent
produces

@example
cp foo @var{dest1}; \
 cp foo @var{dest2}
@end example

The lines containing @code{@@example} and @code{@@end example} will
disappear from the output.  To make the output look good, you should
put a blank line before the @code{@@example} and another blank line
after the @code{@@end example}.  Blank lines inside the beginning
@code{@@example} and the ending @code{@@end example}, on the other
hand, do appear in the output.

@quotation Caution
Do not use tabs in the lines of an example!  (Or anywhere else in
Texinfo, except in verbatim environments.)  @TeX{} treats tabs as
single spaces, and that is not what they look like.  In Emacs, you can
use @kbd{M-x untabify} to convert tabs in a region to multiple spaces.
@end quotation

Examples are often, logically speaking, ``in the middle'' of a
paragraph, and the text that continues afterwards should not be
indented, as in the example above.  The @code{@@noindent} command
prevents a piece of text from being indented as if it were a new
paragraph (@pxref{noindent,,@code{@@noindent}}.

If you want to embed code fragments within sentences, instead of
displaying them, use the @code{@@code} command or its relatives
(@pxref{code,,@code{@@code}}).

If you wish to write a ``comment'' on a line of an example in the
normal roman font, you can use the @code{@@r} command (@pxref{Fonts}).


@node verbatim
@section @code{@@verbatim}: Literal Text
@findex verbatim
@cindex Verbatim environment

Use the @code{@@verbatim} environment for printing of text that may
contain special characters or commands that should not be interpreted,
such as computer input or output (@code{@@example} interprets its text
as regular Texinfo commands).  This is especially useful for including automatically
generated files in a Texinfo manual.

In general, the output will be just the same as the input.  No
character substitutions are made, e.g., all spaces and blank lines are
significant, including tabs.  In the printed manual, the text is
typeset in a fixed-width font, and not indented or filled.

Write a @code{@@verbatim} command at the beginning of a line by itself.
This line will disappear from the output.  Mark the end of the verbatim
block with a @code{@@end verbatim} command, also written at the
beginning of a line by itself.  The @code{@@end verbatim} will also
disappear from the output.

For example:
@c oops, got to trick this a bit: can't use @end verbatim inside @verbatim

@example
@exdent @t{@@verbatim}
@exdent @t{@{}
@exdent @key{TAB}@t{@@command with strange characters: @@'e}
@exdent @t{expand@key{TAB}me}
@exdent @t{@}}
@exdent @t{@@end verbatim}
@end example

@noindent
This produces:

@verbatim
{
        @command with strange characters: @'e
expand	me
}
@end verbatim

Since the lines containing @code{@@verbatim} and @code{@@end verbatim}
produce no output, typically you should put a blank line before the
@code{@@verbatim} and another blank line after the @code{@@end
verbatim}.  Blank lines between the beginning @code{@@verbatim} and
the ending @code{@@end verbatim} will appear in the output.

@cindex Verbatim, small
@cindex Small verbatim
You can get a ``small'' verbatim by enclosing the @code{@@verbatim} in
an @code{@@smallformat} environment, as shown here:

@c more cheating ...
@smallexample
@exdent @t{@@smallformat}
@exdent @t{@@verbatim}
@exdent @t{... still verbatim, but in a smaller font ...}
@exdent @t{@@end verbatim}
@exdent @t{@@end smallformat}
@end smallexample

Finally, a word of warning: it is not reliable to use
@code{@@verbatim} inside other Texinfo constructs.


@node verbatiminclude
@section @code{@@verbatiminclude} @var{file}: Include a File Verbatim
@cindex Verbatim, include file
@cindex Including a file verbatim
@findex verbatiminclude

You can include the exact contents of a file in the document with the
@code{@@verbatiminclude} command:

@example
@@verbatiminclude @var{filename}
@end example

The contents of @var{filename} is printed in a verbatim environment
(@pxref{verbatim,,@code{@@verbatim}}).  Generally, the file is printed
exactly as it is, with all special characters and white space
retained.  No indentation is added; if you want indentation, enclose
the @code{@@verbatiminclude} within @code{@@example}
(@pxref{example,,@code{@@example}}).

The name of the file is taken literally, with a single exception:
@code{@@value@{@var{var}@}} references are expanded.  This makes it
possible to include files in other directories within a distribution,
for instance:

@example
@@verbatiminclude @@value@{top_srcdir@}/NEWS
@end example

@noindent (You still have to get @code{top_srcdir} defined in the
first place.)

For a method on printing the file contents in a smaller font size, see
the end of the previous section on @code{@@verbatim}.


@node lisp
@section @code{@@lisp}: Marking a Lisp Example
@findex lisp
@cindex Lisp example

The @code{@@lisp} command is used for Lisp code.  It is synonymous
with the @code{@@example} command.

@lisp
This is an example of text written between an
@code{@@lisp} command and an @code{@@end lisp} command.
@end lisp

Use @code{@@lisp} instead of @code{@@example} to preserve information
regarding the nature of the example.  This is useful, for example, if
you write a function that evaluates only and all the Lisp code in a
Texinfo file.  Then you can use the Texinfo file as a Lisp
library.@footnote{It would be straightforward to extend Texinfo to work
in a similar fashion for C, Fortran, or other languages.}

Mark the end of @code{@@lisp} with @code{@@end lisp} on a line by
itself.


@node small
@section @code{@@small@dots{}} Block Commands
@cindex Small examples
@cindex Examples in smaller fonts
@cindex Lisp examples in smaller fonts
@findex smalldisplay
@findex smallexample
@findex smallformat
@findex smalllisp

In addition to the regular @code{@@example} and @code{@@lisp} commands,
Texinfo has ``small'' example-style commands.  These are
@code{@@smalldisplay}, @code{@@smallexample}, @code{@@smallformat}, and
@code{@@smalllisp}.

In Info, the @code{@@small@dots{}} commands are equivalent to their
non-small companion commands.

In @TeX{}, however, the @code{@@small@dots{}} commands typeset text in
a smaller font than the non-small example commands.  Consequently,
many examples containing long lines fit on a page without needing to
be shortened.

Mark the end of an @code{@@small@dots{}} block with a corresponding
@code{@@end small@dots{}}.  For example, pair @code{@@smallexample} with
@code{@@end smallexample}.

Here is an example of the font used by the @code{@@small@dots{}}
commands (in Info, the output will be the same as usual):

@smallexample
@dots{} to make sure that you have the freedom to
distribute copies of free software (and charge for
this service if you wish), that you receive source
code or can get it if you want it, that you can
change the software or use pieces of it in new free
programs; and that you know you can do these things.
@end smallexample

The @code{@@small@dots{}} commands make it easier to prepare manuals
without forcing you to edit examples by hand to fit them onto narrower
pages.

As a general rule, a printed document looks much better if you use
only one of (for instance) @code{@@example} or @code{@@smallexample}
consistently within a chapter.


@node display
@section @code{@@display} and @code{@@smalldisplay}
@cindex Display formatting
@findex display

The @code{@@display} command begins a kind of example, where each line
of input produces a line of output, and the output is indented.  It is
thus like the @code{@@example} command except that, in a printed
manual, @code{@@display} does not select the fixed-width font.  In
fact, it does not specify the font at all, so that the text appears in
the same font it would have appeared in without the @code{@@display}
command.

@display
This is an example of text written between an @code{@@display} command
and an @code{@@end display} command.  The @code{@@display} command
indents the text, but does not fill it.
@end display

@findex smalldisplay
Texinfo also provides a command @code{@@smalldisplay}, which is like
@code{@@display} but uses a smaller font in @code{@@smallbook} format.
@xref{small}.

The @code{@@table} command (@pxref{table}) does not work inside
@code{@@display}.  Since @code{@@display} is line-oriented, it doesn't
make sense to use them together.  If you want to indent a table, try
@code{@@quotation} (@pxref{quotation}).


@node format
@section @code{@@format} and @code{@@smallformat}
@findex format

The @code{@@format} command is similar to @code{@@example} except
that, in the printed manual, @code{@@format} does not select the
fixed-width font and does not narrow the margins.

@format
This is an example of text written between an @code{@@format} command
and an @code{@@end format} command.  As you can see
from this example,
the @code{@@format} command does not fill the text.
@end format

@findex smallformat
Texinfo also provides a command @code{@@smallformat}, which is like
@code{@@format} but uses a smaller font in @code{@@smallbook} format.
@xref{small}.



@node exdent
@section @code{@@exdent}: Undoing a Line's Indentation
@cindex Indentation undoing
@findex exdent

The @code{@@exdent} command removes any indentation a line might have.
The command is written at the beginning of a line and applies only to
the text that follows the command that is on the same line.  Do not use
braces around the text.  In a printed manual, the text on an
@code{@@exdent} line is printed in the roman font.@refill

@code{@@exdent} is usually used within examples.  Thus,@refill

@example
@group
@@example
This line follows an @@@@example command.
@@exdent This line is exdented.
This line follows the exdented line.
The @@@@end example comes on the next line.
@@end example
@end group
@end example

@noindent
produces

@example
@group
This line follows an @@example command.
@exdent This line is exdented.
This line follows the exdented line.
The @@end example comes on the next line.
@end group
@end example

In practice, the @code{@@exdent} command is rarely used.
Usually, you un-indent text by ending the example and
returning the page to its normal width.@refill


@node flushleft & flushright
@section @code{@@flushleft} and @code{@@flushright}
@findex flushleft
@findex flushright
@cindex Ragged right
@cindex Ragged left

The @code{@@flushleft} and @code{@@flushright} commands line up the
ends of lines on the left and right margins of a page,
but do not fill the text.  The commands are written on lines of their
own, without braces.  The @code{@@flushleft} and @code{@@flushright}
commands are ended by @code{@@end flushleft} and @code{@@end
flushright} commands on lines of their own.@refill

@need 1500
For example,

@example
@group
@@flushleft
This text is
written flushleft.
@@end flushleft
@end group
@end example

@noindent
produces

@quotation
@flushleft
This text is
written flushleft.
@end flushleft
@end quotation


@code{@@flushright} produces the type of indentation often used in the
return address of letters.  For example,

@example
@group
@@flushright
Here is an example of text written
flushright.  The @@code@{@@flushright@} command
right justifies every line but leaves the
left end ragged.
@@end flushright
@end group
@end example

@noindent
produces

@flushright
Here is an example of text written
flushright.  The @code{@@flushright} command
right justifies every line but leaves the
left end ragged.
@end flushright


@node noindent
@section @code{@@noindent}: Omitting Indentation
@cindex Omitting indentation
@cindex Suppressing indentation
@cindex Indentation, omitting
@findex noindent

An example or other inclusion can break a paragraph into segments.
Ordinarily, the formatters indent text that follows an example as a new
paragraph.  You can prevent this on a case-by-case basis by writing
@code{@@noindent} at the beginning of a line, preceding the continuation
text.  You can also disable indentation for all paragraphs globally with
@code{@@paragraphindent} (@pxref{paragraphindent, Paragraph Indenting}).

It is best to write @code{@@noindent} on a line by itself, since in most
environments, spaces following the command will not be ignored.  It's ok
to use it at the beginning of a line, with text following, outside of
any environment.

@need 1500
For example:

@example
@group
@@example
This is an example
@@end example

@@noindent
This line is not indented.  As you can see, the
beginning of the line is fully flush left with the line
that follows after it.  (This whole example is between
@@code@{@@@@display@} and @@code@{@@@@end display@}.)
@end group
@end example

@noindent produces:

@display

@example
This is an example
@end example

@noindent
This line is not indented.  As you can see, the
beginning of the line is fully flush left with the line
that follows after it.  (This whole example is between
@code{@@display} and @code{@@end display}.)

@end display

To adjust the number of blank lines properly in the Info file output,
remember that the line containing @code{@@noindent} does not generate a
blank line, and neither does the @code{@@end example} line.

In the Texinfo source file for this manual, each line that says
`produces' is preceded by @code{@@noindent}.

Do not put braces after an @code{@@noindent} command; they are not
necessary, since @code{@@noindent} is a command used outside of
paragraphs (@pxref{Command Syntax}).


@node indent
@section @code{@@indent}: Forcing Indentation
@cindex Forcing indentation
@cindex Inserting indentation
@cindex Indentation, forcing
@findex indent

@indent
To complement the @code{@@noindent} command (see the previous
section), Texinfo provides the @code{@@indent} command that forces a
paragraph to be indented.  This paragraph, for instance, is indented
using an @code{@@indent} command.  The first paragraph of a section is
the most likely place to use @code{@@indent}, to override the normal
behavior of no indentation there (@pxref{paragraphindent}).

It is best to write @code{@@indent} on a line by itself, since in most
environments, spaces following the command will not be ignored.  The
@code{@@indent} line will not generate a blank line in the Info output
within an environment.

However, it is ok to use it at the beginning of a line, with text
following, outside of any environment.

Do not put braces after an @code{@@indent} command; they are not
necessary, since @code{@@indent} is a command used outside of
paragraphs (@pxref{Command Syntax}).


@node cartouche
@section @code{@@cartouche}: Rounded Rectangles Around Examples
@findex cartouche
@cindex Box with rounded corners
@cindex Rounded rectangles, around examples

In a printed manual, the @code{@@cartouche} command draws a box with
rounded corners around its contents.  In HTML, a normal rectangle is
drawn (that's the best HTML can do).  @code{@@cartouche} has no effect
in Info output.

You can use this command to further highlight an example or quotation.
For instance, you could write a manual in which one type of example is
surrounded by a cartouche for emphasis.

For example,

@example
@@cartouche
@@example
% pwd
/usr/local/share/emacs
@@end example
@@end cartouche
@end example

@noindent
surrounds the two-line example with a box with rounded corners, in the
printed manual.

The output from the example looks like this (if you're reading this in
Info, you'll see the @code{@@cartouche} had no effect):

@cartouche
@example
% pwd
/usr/local/info
@end example
@end cartouche

For proper output in HTML, it's necessary to put the
@code{@@cartouche} around the @code{@@example}, and not the other way
around.  This limitation of @command{makeinfo} may be removed one day.

@code{@@cartouche} also implies @code{@@group} (@pxref{group}).

@node Lists and Tables
@chapter Lists and Tables
@cindex Making lists and tables
@cindex Lists and tables, making
@cindex Tables and lists, making

Texinfo has several ways of making lists and tables.  Lists can be
bulleted or numbered; two-column tables can highlight the items in
the first column; multi-column tables are also supported.

@menu
* Introducing Lists::           Texinfo formats lists for you.
* itemize::                     How to construct a simple list.
* enumerate::                   How to construct a numbered list.
* Two-column Tables::           How to construct a two-column table.
* Multi-column Tables::         How to construct generalized tables.
@end menu

@node Introducing Lists
@section Introducing Lists

Texinfo automatically indents the text in lists or tables, and numbers
an enumerated list.  This last feature is useful if you modify the
list, since you do not need to renumber it yourself.@refill

Numbered lists and tables begin with the appropriate @@-command at the
beginning of a line, and end with the corresponding @code{@@end}
command on a line by itself.  The table and itemized-list commands
also require that you write formatting information on the same line as
the beginning @@-command.@refill

Begin an enumerated list, for example, with an @code{@@enumerate}
command and end the list with an @code{@@end enumerate} command.
Begin an itemized list with an @code{@@itemize} command, followed on
the same line by a formatting command such as @code{@@bullet}, and end
the list with an @code{@@end itemize} command.@refill
@findex end

Precede each element of a list with an @code{@@item} or @code{@@itemx}
command.@refill

@sp 1
@noindent
Here is an itemized list of the different kinds of table and lists:@refill

@itemize @bullet
@item
Itemized lists with and without bullets.

@item
Enumerated lists, using numbers or letters.

@item
Two-column tables with highlighting.
@end itemize

@sp 1
@noindent
Here is an enumerated list with the same items:@refill

@enumerate
@item
Itemized lists with and without bullets.

@item
Enumerated lists, using numbers or letters.

@item
Two-column tables with highlighting.
@end enumerate

@sp 1
@noindent
And here is a two-column table with the same items and their
@w{@@-commands}:@refill

@table @code
@item @@itemize
Itemized lists with and without bullets.

@item @@enumerate
Enumerated lists, using numbers or letters.

@item @@table
@itemx @@ftable
@itemx @@vtable
Two-column tables, optionally with indexing.
@end table


@node itemize
@section @code{@@itemize}: Making an Itemized List
@cindex Itemization
@findex itemize

The @code{@@itemize} command produces sequences of indented
paragraphs, with a bullet or other mark inside the left margin
at the beginning of each paragraph for which such a mark is desired.@refill

@cindex @code{@@w}, for blank items
Begin an itemized list by writing @code{@@itemize} at the beginning of
a line.  Follow the command, on the same line, with a character or a
Texinfo command that generates a mark.  Usually, you will write
@code{@@bullet} after @code{@@itemize}, but you can use
@code{@@minus}, or any command or character that results in a single
character in the Info file.  If you don't want any mark at all, use
@code{@@w}.  (When you write the mark command such as
@code{@@bullet} after an @code{@@itemize} command, you may omit the
@samp{@{@}}.)  If you don't specify a mark command, the default is
@code{@@bullet}.

Write the text of the indented paragraphs themselves after the
@code{@@itemize}, up to another line that says @code{@@end
itemize}.@refill

@findex item
At the beginning of each paragraph for which a mark in the margin is
desired, write a line that starts with @code{@@item}.  It is ok to
have text following the @code{@@item}.

Usually, you should put a blank line before an @code{@@item}.  This
puts a blank line in the Info file. (@TeX{} inserts the proper
interline whitespace in either case.)  Except when the entries are
very brief, these blank lines make the list look better.@refill

Here is an example of the use of @code{@@itemize}, followed by the
output it produces.  @code{@@bullet} produces an @samp{*} in Info and a
round dot in @TeX{}.

@example
@group
@@itemize @@bullet
@@item
Some text for foo.

@@item
Some text
for bar.
@@end itemize
@end group
@end example

@noindent
This produces:

@quotation
@itemize @bullet
@item
Some text for foo.

@item
Some text
for bar.
@end itemize
@end quotation

Itemized lists may be embedded within other itemized lists.  Here is a
list marked with dashes embedded in a list marked with bullets:@refill

@example
@group
@@itemize @@bullet
@@item
First item.

@@itemize @@minus
@@item
Inner item.

@@item
Second inner item.
@@end itemize

@@item
Second outer item.
@@end itemize
@end group
@end example

@noindent
This produces:

@quotation
@itemize @bullet
@item
First item.

@itemize @minus
@item
Inner item.

@item
Second inner item.
@end itemize

@item
Second outer item.
@end itemize
@end quotation


@node enumerate
@section @code{@@enumerate}: Making a Numbered or Lettered List
@cindex Enumeration
@findex enumerate

@code{@@enumerate} is like @code{@@itemize} (@pxref{itemize,,
@code{@@itemize}}), except that the labels on the items are
successive integers or letters instead of bullets.

Write the @code{@@enumerate} command at the beginning of a line.  The
command does not require an argument, but accepts either a number or a
letter as an option.  Without an argument, @code{@@enumerate} starts the
list with the number @samp{1}.  With a numeric argument, such as
@samp{3}, the command starts the list with that number.  With an upper
or lower case letter, such as @samp{a} or @samp{A}, the command starts
the list with that letter.

Write the text of the enumerated list in the same way as an itemized
list: write a line starting with @code{@@item} at the beginning of
each paragraph that you want enumerated.  It is ok to have text
following the @code{@@item}.

You should put a blank line between entries in the list.
This generally makes it easier to read the Info file.

@need 1500
Here is an example of @code{@@enumerate} without an argument:

@example
@group
@@enumerate
@@item
Underlying causes.

@@item
Proximate causes.
@@end enumerate
@end group
@end example

@noindent
This produces:

@enumerate
@item
Underlying causes.

@item
Proximate causes.
@end enumerate
@sp 1
Here is an example with an argument of @kbd{3}:@refill
@sp 1
@example
@group
@@enumerate 3
@@item
Predisposing causes.

@@item
Precipitating causes.

@@item
Perpetuating causes.
@@end enumerate
@end group
@end example

@noindent
This produces:

@enumerate 3
@item
Predisposing causes.

@item
Precipitating causes.

@item
Perpetuating causes.
@end enumerate
@sp 1
Here is a brief summary of the alternatives.  The summary is constructed
using @code{@@enumerate} with an argument of @kbd{a}.@refill
@sp 1
@enumerate a
@item
@code{@@enumerate}

Without an argument, produce a numbered list, starting with the number
1.@refill

@item
@code{@@enumerate @var{positive-integer}}

With a (positive) numeric argument, start a numbered list with that
number.  You can use this to continue a list that you interrupted with
other text.@refill

@item
@code{@@enumerate @var{upper-case-letter}}

With an upper case letter as argument, start a list
in which each item is marked
by a letter, beginning with that upper case letter.@refill

@item
@code{@@enumerate @var{lower-case-letter}}

With a lower case letter as argument, start a list
in which each item is marked by
a letter, beginning with that lower case letter.@refill
@end enumerate

You can also nest enumerated lists, as in an outline.@refill

@node Two-column Tables
@section Making a Two-column Table
@cindex Tables, making two-column
@findex table

@code{@@table} is similar to @code{@@itemize} (@pxref{itemize,,
@code{@@itemize}}), but allows you to specify a name or heading line for
each item.  The @code{@@table} command is used to produce two-column
tables, and is especially useful for glossaries, explanatory
exhibits, and command-line option summaries.

@menu
* table::                       How to construct a two-column table.
* ftable vtable::               Automatic indexing for two-column tables.
* itemx::                       How to put more entries in the first column.
@end menu

@node table
@subsection Using the @code{@@table} Command

@cindex Definition lists, typesetting
Use the @code{@@table} command to produce two-column tables.  It is
usually listed for ``definition lists'' of various sorts, where you
have a list of terms and a brief text with each one.

Write the @code{@@table} command at the beginning of a line, after a
blank line, and follow it on the same line with an argument that is a
Texinfo ``indicating'' command such as @code{@@code}, @code{@@samp},
@code{@@var}, @code{@@option}, or @code{@@kbd} (@pxref{Indicating}).

This command will be applied to the text that goes into the first
column of each item and thus determines how it will be highlighted.
For example, @code{@@table @@code} will cause the text in the first
column to be output as if it @code{@@code} command.

@findex asis
You may also use the @code{@@asis} command as an argument to
@code{@@table}.  @code{@@asis} is a command that does nothing; if you
use this command after @code{@@table}, the first column entries are
output without added highlighting (``as is'').

The @code{@@table} command works with other commands besides those
explicitly mentioned here.  However, you can only use commands that
normally take arguments in braces.  (In this case, however, you use
the command name without an argument, because the subsequent
@code{@@item}'s will supply the argument.)

@findex item
Begin each table entry with an @code{@@item} command at the beginning
of a line.  Write the first column text on the same line as the
@code{@@item} command.  Write the second column text on the line
following the @code{@@item} line and on subsequent lines.  (You do not
need to type anything for an empty second column entry.)  You may
write as many lines of supporting text as you wish, even several
paragraphs.  But only the text on the same line as the @code{@@item}
will be placed in the first column (including any footnotes).

Normally, you should put a blank line before an @code{@@item} line.
This puts a blank line in the Info file.  Except when the entries are
very brief, a blank line looks better.

End the table with a line consisting of @code{@@end table}, followed
by a blank line.  @TeX{} will always start a new paragraph after the
table, so the blank line is needed for the Info output to be analogous.

@need 1500
The following table, for example, highlights the text in the first
column with an @code{@@samp} command:

@example
@group
@@table @@samp
@@item foo
This is the text for
@@samp@{foo@}.

@@item bar
Text for @@samp@{bar@}.
@@end table
@end group
@end example

@noindent
This produces:

@table @samp
@item foo
This is the text for
@samp{foo}.
@item bar
Text for @samp{bar}.
@end table

If you want to list two or more named items with a single block of
text, use the @code{@@itemx} command.  (@xref{itemx,,@code{@@itemx}}.)


@node ftable vtable
@subsection @code{@@ftable} and @code{@@vtable}
@cindex Tables with indexes
@cindex Indexing table entries automatically
@findex ftable
@findex vtable

The @code{@@ftable} and @code{@@vtable} commands are the same as the
@code{@@table} command except that @code{@@ftable} automatically enters
each of the items in the first column of the table into the index of
functions and @code{@@vtable} automatically enters each of the items in
the first column of the table into the index of variables.  This
simplifies the task of creating indices.  Only the items on the same
line as the @code{@@item} commands are indexed, and they are indexed in
exactly the form that they appear on that line.  @xref{Indices},
for more information about indices.@refill

Begin a two-column table using @code{@@ftable} or @code{@@vtable} by
writing the @@-command at the beginning of a line, followed on the same
line by an argument that is a Texinfo command such as @code{@@code},
exactly as you would for an @code{@@table} command; and end the table
with an @code{@@end ftable} or @code{@@end vtable} command on a line by
itself.

See the example for @code{@@table} in the previous section.

@node itemx
@subsection @code{@@itemx}
@cindex Two named items for @code{@@table}
@findex itemx

Use the @code{@@itemx} command inside a table when you have two or more
first column entries for the same item, each of which should appear on a
line of its own.

Use @code{@@item} for the first entry, and @code{@@itemx} for all
subsequent entries; @code{@@itemx} must always follow an @code{@@item}
command, with no blank line intervening.

The @code{@@itemx} command works exactly like @code{@@item} except
that it does not generate extra vertical space above the first column
text.  If you have multiple consecutive @code{@@itemx} commands, do
not insert any blank lines between them.

For example,

@example
@group
@@table @@code
@@item upcase
@@itemx downcase
These two functions accept a character or a string as
argument, and return the corresponding upper case (lower
case) character or string.
@@end table
@end group
@end example

@noindent
This produces:

@table @code
@item upcase
@itemx downcase
These two functions accept a character or a string as
argument, and return the corresponding upper case (lower
case) character or string.@refill
@end table

@noindent
(Note also that this example illustrates multi-line supporting text in
a two-column table.)@refill


@node Multi-column Tables
@section @code{@@multitable}: Multi-column Tables
@cindex Tables, making multi-column
@findex multitable

@code{@@multitable} allows you to construct tables with any number of
columns, with each column having any width you like.

You define the column widths on the @code{@@multitable} line itself, and
write each row of the actual table following an @code{@@item} command,
with columns separated by an @code{@@tab} command.  Finally, @code{@@end
multitable} completes the table.  Details in the sections below.

@menu
* Multitable Column Widths::    Defining multitable column widths.
* Multitable Rows::             Defining multitable rows, with examples.
@end menu

@node Multitable Column Widths
@subsection Multitable Column Widths
@cindex Multitable column widths
@cindex Column widths, defining for multitables
@cindex Widths, defining multitable column

You can define the column widths for a multitable in two ways: as
fractions of the line length; or with a prototype row.  Mixing the two
methods is not supported.  In either case, the widths are defined
entirely on the same line as the @code{@@multitable} command.

@enumerate
@item
@findex columnfractions
@cindex Line length, column widths as fraction of
To specify column widths as fractions of the line length, write
@code{@@columnfractions} and the decimal numbers (presumably less than
1; a leading zero is allowed and ignored) after the
@code{@@multitable} command, as in:

@example
@@multitable @@columnfractions .33 .33 .33
@end example

The fractions need not add up exactly to 1.0, as these do not.  This
allows you to produce tables that do not need the full line length.

@item
@cindex Prototype row, column widths defined by
To specify a prototype row, write the longest entry for each column
enclosed in braces after the @code{@@multitable} command.  For example:

@example
@@multitable @{some text for column one@} @{for column two@}
@end example

@noindent
The first column will then have the width of the typeset `some text for
column one', and the second column the width of `for column two'.

The prototype entries need not appear in the table itself.

Although we used simple text in this example, the prototype entries can
contain Texinfo commands; markup commands such as @code{@@code} are
particularly likely to be useful.

@end enumerate


@node Multitable Rows
@subsection Multitable Rows
@cindex Multitable rows
@cindex Rows, of a multitable

@findex item
@findex tab
After the @code{@@multitable} command defining the column widths (see
the previous section), you begin each row in the body of a multitable
with @code{@@item}, and separate the column entries with @code{@@tab}.
Line breaks are not special within the table body, and you may break
input lines in your source file as necessary.

@findex headitem
@cindex Heading row, in table
@cindex <thead> HTML tag
You can also use @code{@@headitem} instead of @code{@@item} to produce
a @dfn{heading row}.  The @TeX{} output for such a row is in bold, and
the HTML, XML, and Docbook output uses the @code{<thead>} tag.  In
Info, the heading row is followed by a separator line made of dashes
(@samp{-} characters).

Here is a complete example of a multi-column table (the text is from
@cite{The GNU Emacs Manual}, @pxref{Split Window,, Splitting Windows,
emacs, The GNU Emacs Manual}):

@example
@@multitable @@columnfractions .15 .45 .4
@@headitem Key @@tab Command @@tab Description
@@item C-x 2
@@tab @@code@{split-window-vertically@}
@@tab Split the selected window into two windows,
with one above the other.
@@item C-x 3
@@tab @@code@{split-window-horizontally@}
@@tab Split the selected window into two windows
positioned side by side.
@@item C-Mouse-2
@@tab
@@tab In the mode line or scroll bar of a window,
split that window.
@@end multitable
@end example

@noindent produces:

@multitable @columnfractions .15 .45 .4
@headitem Key @tab Command @tab Description
@item C-x 2
@tab @code{split-window-vertically}
@tab Split the selected window into two windows,
with one above the other.
@item C-x 3
@tab @code{split-window-horizontally}
@tab Split the selected window into two windows
positioned side by side.
@item C-Mouse-2
@tab
@tab In the mode line or scroll bar of a window,
split that window.
@end multitable


@node Special Displays
@chapter Special Displays
@cindex Special displays

The commands in this chapter allow you to write text that is specially
displayed (output format permitting), outside of the normal document
flow.

One set of such commands is for creating ``floats'', that is, figures,
tables, and the like, set off from the main text, possibly numbered,
captioned, and/or referred to from elsewhere in the document.  Images
are often included in these displays.

Another group of commands is for creating footnotes in Texinfo.

@menu
* Floats::                      Figures, tables, and the like.
* Images::                      Including graphics and images.
* Footnotes::                   Writing footnotes.
@end menu


@node Floats
@section Floats
@cindex Floats, in general

A @dfn{float} is a display which is set off from the main text.  It is
typically labelled as being a ``Figure'', ``Table'', ``Example'', or
some similar type.

@cindex Floating, not yet implemented
A float is so-named because, in principle, it can be moved to the
bottom or top of the current page, or to a following page, in the
printed output.  (Floating does not make sense in other output
formats.)  In the present version of Texinfo, however, this floating
is unfortunately not yet implemented.  Instead, the floating material
is simply output at the current location, more or less as if it were
an @code{@@group} (@pxref{group,,@code{@@group}}).

@menu
* float::                       Producing floating material.
* caption shortcaption::        Specifying descriptions for floats.
* listoffloats::                A table of contents for floats.
@end menu


@node float
@subsection @code{@@float} [@var{type}][,@var{label}]: Floating Material
@findex float
@cindex Float environment

To produce floating material, enclose the material you want to be
displayed separate between @code{@@float} and @code{@@end float}
commands, on lines by themselves.

Floating material uses @code{@@image} to display an already-existing
graphic (@pxref{Images}), or @code{@@multitable} to display a table
(@pxref{Multi-column Tables}).  However, the contents of the float can
be anything.  Here's an example with simple text:

@example
@@float Figure,fig:ex1
This is an example float.
@@end float
@end example

@noindent And the output:

@float Figure,fig:ex1
This is an example float.
@end float

As shown in the example, @code{@@float} takes two arguments (separated
by a comma), @var{type} and @var{label}.  Both are optional.

@table @var
@item type
Specifies the sort of float this is; typically a word such as
``Figure'', ``Table'', etc.  If not given, and @var{label} is, any
cross-referencing will simply use a bare number.

@item label
Specifies a cross-reference label for this float.  If given, this
float is automatically given a number, and will appear in any
@code{@@listoffloats} output (@pxref{listoffloats}).  Cross-references
to @var{label} are allowed.

@cindex Floats, making unnumbered
@cindex Unnumbered float, creating
On the other hand, if @var{label} is not given, then the float will
not be numbered and consequently will not appear in the
@code{@@listoffloats} output or be cross-referenceable.
@end table

@noindent Normally, you specify both @var{type} and @var{label}, to get a
labeled and numbered float.

@cindex Floats, numbering of
@cindex Numbering of floats
In Texinfo, all floats are numbered the same way: with the chapter
number (or appendix letter), a period, and the float number, which
simply counts 1, 2, 3, @dots{}, and is reset at each chapter.  Each
float type is counted independently.  

Floats within an @code{@@unnumbered} are numbered, or outside of any
chapter, are simply numbered consecutively from 1.

These numbering conventions are not, at present, changeable.


@node caption shortcaption
@subsection @code{@@caption} & @code{@@shortcaption}
@findex caption
@findex shortcaption
@cindex Captions, for floats
@cindex Short captions, for lists of floats

You may write an @code{@@caption} anywhere within a @code{@@float}
environment, to define a caption for the float.  It is not allowed in
any other context.  @code{@@caption} takes a single argument, enclosed
in braces.  Here's an example:

@example
@@float
An example float, with caption.
@@caption@{Caption for example float.@}
@@end float
@end example

@noindent The output is:

@float
An example float, with caption.
@caption{Caption for example float.}
@end float

@code{@@caption} can appear anywhere within the float; it is not
processed until the @code{@@end float}.  The caption text is usually a
sentence or two, but may consist of several paragraphs if necessary.

In the output, the caption always appears below the float; this is not
currently changeable.  It is preceded by the float type and/or number,
as specified to the @code{@@float} command (see the previous section).

The @code{@@shortcaption} command likewise may be used only within
@code{@@float}, and takes a single argument in braces.  The short
caption text is used instead of the caption text in a list of floats
(see the next section).  Thus, you can write a long caption for the
main document, and a short title to appear in the list of floats.  For
example:

@example
@@float
... as above ...
@@shortcaption@{Text for list of floats.@}
@@end float
@end example

The text for @code{@@caption} and @code{@@shortcaption} may not
contain comments (@code{@@c}), verbatim text (@code{@@verb}),
environments such as @code{@@example}, or other complex constructs.


@node listoffloats
@subsection @code{@@listoffloats}: Tables of Contents for Floats
@findex listoffloats
@cindex List of floats
@cindex Floats, list of
@cindex Table of contents, for floats

You can write a @code{@@listoffloats} command to generate a list of
floats for a given float type (@pxref{float}), analogous to the
document's overall table of contents.  Typically, it is written in its
own @code{@@unnumbered} node to provide a heading and structure,
rather like @code{@@printindex} (@pxref{Printing Indices & Menus}).

@code{@@listoffloats} takes one optional argument, the float type.
Here's an example:

@example
@@node List of Figures
@@unnumbered List of Figures
@@listoffloats Figure
@end example

@noindent And the output from @code{@@listoffloats}:

@display
@listoffloats Figure
@end display

Without any argument, @code{@@listoffloats} generates a list of
floats for which no float type was specified, i.e., no first argument
to the @code{@@float} command (@pxref{float}).

Each line in the list of floats contains the float type (if any),
the float number, and the caption, if any---the @code{@@shortcaption}
argument, if it was specified, else the @code{@@caption} argument.
In Info, the result is a menu where each float can be selected.  In
HTML, each line is a link to the float.  In printed output, the page
number is included.

Unnumbered floats (those without cross-reference labels) are omitted
from the list of floats.


@node Images
@section Inserting Images

@cindex Images, inserting
@cindex Pictures, inserting
@findex image

You can insert an image given in an external file with the
@code{@@image} command.  Although images can be used anywhere,
including the middle of a paragraph, we describe them in this chapter
since they are most often part of a displayed figure or example.

@menu
* Image Syntax::
* Image Scaling::
@end menu


@node Image Syntax
@subsection Image Syntax

Here is the synopsis of the @code{@@image} command:

@example
@@image@{@var{filename}@r{[,} @var{width}@r{[,} @var{height}@r{[,} @var{alttext}@r{[, }@var{extension}@r{]]]]}@}
@end example

@cindex Formats for images
@cindex Image formats
The @var{filename} argument is mandatory, and must not have an
extension, because the different processors support different formats:

@itemize @bullet
@item
@pindex eps image format
@TeX{} reads the file @file{@var{filename}.eps} (Encapsulated PostScript
format).
@item
@pindex pdftex@r{, and images}
@pindex png image format
@pindex jpeg image format
@pindex pdf image inclusions
pdf@TeX{} reads @file{@var{filename}.png}, @file{@var{filename}.jpg},
@file{@var{filename}.jpeg}, or @file{@var{filename}.pdf} (in that
order).  It also tries uppercase versions of the extensions.  The PDF
format cannot support EPS images, so they must be converted first.
@item
@code{makeinfo} includes @file{@var{filename}.txt} verbatim for
Info output (more or less as if it was an @code{@@example}).
@item
@code{makeinfo} uses the optional fifth argument @var{extension} to
@code{@@image} for the filename extension, if it is specified.  For example:

@pindex XPM image format
@example
@@image@{foo,,,,.xpm@}
@end example

@noindent
will cause @code{makeinfo} to look for @file{foo.xpm} before any others.

@end itemize

The @var{width} and @var{height} arguments are described in the next
section.

For @TeX{} output, if an image is the only thing in a paragraph it
will ordinarily be displayed on a line by itself, respecting the
current environment indentation, but without the normal paragraph
indentation.  If you want it centered, use @code{@@center}
(@pxref{titlefont center sp,,@code{@@titlefont @@center @@sp}}).

@cindex Alt attribute for images
@cindex Images, alternate text for
@findex - (in image alt string)
For HTML output, @code{makeinfo} sets the @dfn{alt attribute} for
inline images to the optional @var{alttext} (fourth) argument to
@code{@@image}, if supplied.  If not supplied, @code{makeinfo} uses
the full file name of the image being displayed.  The @var{alttext} is
taken as Texinfo text, so special characters such as @samp{"} and
@samp{<} and @samp{&} are escaped in the HTML and XML output; also,
you can get an empty @code{alt} string with @code{@@-} (a command
that produces no output; @pxref{- and hyphenation}).

For Info output, the @code{alt} string is also processed as Texinfo
text and output.  In this case, @samp{\} is escaped as @samp{\\} and
@samp{"} as @samp{\"}; no other escapes are done.

@cindex PNG image format
@cindex JPEG image format
If you do not supply the optional @var{extension} (fifth) argument,
@code{makeinfo} first tries @file{@var{filename}.png}; if that does
not exist, it tries @file{@var{filename}.jpg}.  If that does not exist
either, it complains.

In Info output, @code{makeinfo} writes a reference to the binary image
file (trying @var{filename} suffixed with @file{@var{extension}},
@file{@var{.extension}}, @file{.png}, or @file{.jpg}, in that order)
if one exists.  It also literally includes the @file{.txt} file if one
exists.  This way, Info readers which can display images (such as the
Emacs Info browser, running under X) can do so, whereas Info readers
which can only use text (such as the standalone Info reader) can
display the textual version.

@cindex @samp{^@@^H} for images in Info
The implementation of this is to put the following construct into the
Info output:

@example
^@@^H[image src="@var{binaryfile}" text="@var{txtfile}"
           alt="@var{alttext} ... ^@@^H]
@end example

@noindent where @samp{^@@} and @samp{^H} stand for the actual null and
backspace control characters.  If one of the files is not present, the
corresponding argument is omitted.

The reason for mentioning this here is that older Info browsers (this
feature was introduced in Texinfo version 4.6) will display the above
literally, which, although not pretty, should not be harmful.


@node Image Scaling
@subsection Image Scaling

@cindex Images, scaling
@cindex Scaling images
@cindex Width of images
@cindex Height of images
@cindex Aspect ratio of images
@cindex Distorting images
The optional @var{width} and @var{height} arguments to the
@code{@@image} command (see the previous section) specify the size to
scale the image to.  They are ignored for Info output.  If neither is
specified, the image is presented in its natural size (given in the
file); if only one is specified, the other is scaled proportionately;
and if both are specified, both are respected, thus possibly distorting
the original image by changing its aspect ratio.

@cindex Dimensions and image sizes
The @var{width} and @var{height} may be specified using any valid @TeX{}
dimension, namely:

@table @asis
@item pt
@cindex Points (dimension)
point (72.27pt = 1in)
@item pc
@cindex Picas
pica (1pc = 12pt)
@item bp
@cindex Big points
big point (72bp = 1in)
@item in
@cindex Inches
inch
@item cm
@cindex Centimeters
centimeter (2.54cm = 1in)
@item mm
@cindex Millimeters
millimeter (10mm = 1cm)
@item dd
@cindex Did@^ot points
did@^ot point (1157dd = 1238pt)
@item cc
@cindex Ciceros
cicero (1cc = 12dd)
@item sp
@cindex Scaled points
scaled point (65536sp = 1pt)
@end table

@pindex ridt.eps
For example, the following will scale a file @file{ridt.eps} to one
inch vertically, with the width scaled proportionately:

@example
@@image@{ridt,,1in@}
@end example

@pindex epsf.tex
For @code{@@image} to work with @TeX{}, the file @file{epsf.tex} must be
installed somewhere that @TeX{} can find it.  (The standard location is
@file{@var{texmf}/tex/generic/dvips/epsf.tex}, where @var{texmf} is a
root of your @TeX{} directory tree.)  This file is included in the
Texinfo distribution and is also available from
@uref{ftp://tug.org/tex/epsf.tex}, among other places.

@code{@@image} can be used within a line as well as for displayed
figures.  Therefore, if you intend it to be displayed, be sure to leave
a blank line before the command, or the output will run into the
preceding text.

Image scaling is presently implemented only in @TeX{}, not in HTML or
any other sort of output.


@node Footnotes
@section Footnotes
@cindex Footnotes
@findex footnote

A @dfn{footnote} is for a reference that documents or elucidates the
primary text.@footnote{A footnote should complement or expand upon
the primary text, but a reader should not need to read a footnote to
understand the primary text.  For a thorough discussion of footnotes,
see @cite{The Chicago Manual of Style}, which is published by the
University of Chicago Press.}  Footnotes are distracting; use them
sparingly, if at all.  Standard bibliographical references are better
placed in a bibliography at the end of a document than in footnotes
throughout.

@menu
* Footnote Commands::           How to write a footnote in Texinfo.
* Footnote Styles::             Controlling how footnotes appear in Info.
@end menu


@node Footnote Commands
@subsection Footnote Commands

In Texinfo, footnotes are created with the @code{@@footnote} command.
This command is followed immediately by a left brace, then by the text
of the footnote, and then by a terminating right brace.  Footnotes may
be of any length (they will be broken across pages if necessary), but
are usually short.  The template is:

@example
ordinary text@@footnote@{@var{text of footnote}@}
@end example

As shown here, the @code{@@footnote} command should come right after the
text being footnoted, with no intervening space; otherwise, the footnote
marker might end up starting a line.

For example, this clause is followed by a sample footnote@footnote{Here
is the sample footnote.}; in the Texinfo source, it looks like
this:

@example
@dots{}a sample footnote@@footnote@{Here is the sample
footnote.@}; in the Texinfo source@dots{}
@end example

As you can see, the source includes two punctuation marks next to each
other; in this case, @samp{.@};} is the sequence.  This is normal (the
first ends the footnote and the second belongs to the sentence being
footnoted), so don't worry that it looks odd.

In a printed manual or book, the reference mark for a footnote is a
small, superscripted number; the text of the footnote appears at the
bottom of the page, below a horizontal line.

In Info, the reference mark for a footnote is a pair of parentheses
with the footnote number between them, like this: @samp{(1)}.  The
reference mark is followed by a cross-reference link to the footnote's
text.

In the HTML output, footnote references are marked with a small,
superscripted number which is rendered as a hypertext link to the
footnote text.

By the way, footnotes in the argument of an @code{@@item} command for a
@code{@@table} must be on the same line as the @code{@@item}
(as usual).  @xref{Two-column Tables}.


@node Footnote Styles
@subsection Footnote Styles

Info has two footnote styles, which determine where the text of the
footnote is located:

@itemize @bullet
@cindex @samp{@r{End}} node footnote style
@item
In the `End' node style, all the footnotes for a single node
are placed at the end of that node.  The footnotes are separated from
the rest of the node by a line of dashes with the word
@samp{Footnotes} within it.  Each footnote begins with an
@samp{(@var{n})} reference mark.

@need 700
@noindent
Here is an example of a single footnote in the end of node style:@refill

@example
@group
--------- Footnotes ---------

(1)  Here is a sample footnote.
@end group
@end example

@cindex @samp{@r{Separate}} footnote style
@item
In the `Separate' node style, all the footnotes for a single
node are placed in an automatically constructed node of
their own.  In this style, a ``footnote reference'' follows
each @samp{(@var{n})} reference mark in the body of the
node.  The footnote reference is actually a cross reference
which you use to reach the footnote node.

The name of the node with the footnotes is constructed
by appending @w{@samp{-Footnotes}} to the name of the node
that contains the footnotes. (Consequently, the footnotes'
node for the @file{Footnotes} node is
@w{@file{Footnotes-Footnotes}}!)  The footnotes' node has an
`Up' node pointer that leads back to its parent node.

@noindent
Here is how the first footnote in this manual looks after being
formatted for Info in the separate node style:

@smallexample
@group
File: texinfo.info  Node: Overview-Footnotes, Up: Overview

(1) The first syllable of "Texinfo" is pronounced like "speck", not
"hex". @dots{}
@end group
@end smallexample
@end itemize

Unless your document has long and important footnotes (as in, say,
Gibbon's @cite{Decline and Fall @dots{}}), we recommend the @samp{end}
style, as it is simpler for readers to follow.

@findex footnotestyle
Use the @code{@@footnotestyle} command to specify an Info file's
footnote style.  Write this command at the beginning of a line followed
by an argument, either @samp{end} for the end node style or
@samp{separate} for the separate node style.

@need 700
For example,

@example
@@footnotestyle end
@end example
@noindent
or
@example
@@footnotestyle separate
@end example

Write an @code{@@footnotestyle} command before or shortly after the
end-of-header line at the beginning of a Texinfo file.  (If you
include the @code{@@footnotestyle} command between the start-of-header
and end-of-header lines, the region formatting commands will format
footnotes as specified.)@refill

If you do not specify a footnote style, the formatting commands use
their default style.  Currently, @code{texinfo-format-buffer} and
@code{texinfo-format-region} use the `separate' style and
@code{makeinfo} uses the `end' style.


@node Indices
@chapter Indices
@cindex Indices

Using Texinfo, you can generate indices without having to sort and
collate entries manually.  In an index, the entries are listed in
alphabetical order, together with information on how to find the
discussion of each entry.  In a printed manual, this information
consists of page numbers.  In an Info file, this information is a menu
entry leading to the first node referenced.

Texinfo provides several predefined kinds of index: an index
for functions, an index for variables, an index for concepts, and so
on.  You can combine indices or use them for other than their
canonical purpose.  Lastly, you can define your own new indices.

@xref{Printing Indices & Menus}, for information on how to print
indices.

@menu
* Index Entries::               Choose different words for index entries.
* Predefined Indices::          Use different indices for different kinds
                                 of entries.
* Indexing Commands::           How to make an index entry.
* Combining Indices::           How to combine indices.
* New Indices::                 How to define your own indices.
@end menu


@node Index Entries
@section Making Index Entries
@cindex Index entries, making
@cindex Entries, making index

When you are making index entries, it is good practice to think of the
different ways people may look for something.  Different people
@emph{do not} think of the same words when they look something up.  A
helpful index will have items indexed under all the different words
that people may use.  For example, one reader may think it obvious that
the two-letter names for indices should be listed under ``Indices,
two-letter names'', since the word ``Index'' is the general concept.
But another reader may remember the specific concept of two-letter
names and search for the entry listed as ``Two letter names for
indices''.  A good index will have both entries and will help both
readers.@refill

Like typesetting, the construction of an index is a highly skilled,
professional art, the subtleties of which are not appreciated until you
need to do it yourself.@refill

@xref{Printing Indices & Menus}, for information about printing an index
at the end of a book or creating an index menu in an Info file.@refill


@node Predefined Indices
@section Predefined Indices

Texinfo provides six predefined indices.  Here are their nominal
meanings, abbreviations, and the corresponding index entry commands:

@table @samp
@item cp
@cindex @code{cp} (concept) index
(@code{@@cindex}) concept index, for general concepts.
@item fn
@cindex @code{fn} (function) index
(@code{@@findex}) function index, for function and function-like
names (such as entry points of libraries).
@item ky
@cindex @code{ky} (keystroke) index
(@code{@@kindex}) keystroke index, for keyboard commands.
@item pg
@cindex @code{pg} (program) index
(@code{@@pindex}) program index, for names of programs.
@item tp
@cindex @code{tp} (data type) index
(@code{@@tindex}) data type index, for type names (such as structures
defined in header files).
@item vr
@cindex @code{vr} (variable) index
(@code{@@vindex}) variable index, for variable names (such as global
variables of libraries).
@end table

@noindent
Not every manual needs all of these, and most manuals use only two or
three at most.  The present manual, for example, has two indices: a
concept index and an @@-command index (that is actually the function
index but is called a command index in the chapter heading).

You are not required to use the predefined indices strictly for their
canonical purposes.  For example, suppose you wish to index some C
preprocessor macros.  You could put them in the function index along
with actual functions, just by writing @code{@@findex} commands for
them; then, when you print the ``Function Index'' as an unnumbered
chapter, you could give it the title `Function and Macro Index' and
all will be consistent for the reader.

On the other hand, it is best not to stray too far from the meaning of
the predefined indices.  Otherwise, in the event that your text is
combined with other text from other manuals, the index entries will
not match up.  Instead, define your own new index (@pxref{New
Indices}).

We recommend having a single index in the final document whenever
possible, however many source indices you use, since then readers have
only one place to look.  Two or more source indices can be combined
into one output index using the @code{@@synindex} or
@code{@@syncodeindex} commands (@pxref{Combining Indices}).


@node Indexing Commands
@section Defining the Entries of an Index
@cindex Defining indexing entries
@cindex Index entries
@cindex Entries for an index
@cindex Specifying index entries
@cindex Creating index entries

The data to make an index come from many individual indexing commands
scattered throughout the Texinfo source file.  Each command says to add
one entry to a particular index; after formatting, the index will give
the current page number or node name as the reference.@refill

An index entry consists of an indexing command at the beginning of a
line followed, on the rest of the line, by the entry.@refill

For example, this section begins with the following five entries for
the concept index:@refill

@example
@@cindex Defining indexing entries
@@cindex Index entries, defining
@@cindex Entries for an index
@@cindex Specifying index entries
@@cindex Creating index entries
@end example

Each predefined index has its own indexing command---@code{@@cindex}
for the concept index, @code{@@findex} for the function index, and so
on, as listed in the previous section.

@cindex Writing index entries
@cindex Index entry writing
Concept index entries consist of text.  The best way to write an index
is to choose entries that are terse yet clear.  If you can do this,
the index often looks better if the entries are not capitalized, but
written just as they would appear in the middle of a sentence.
(Capitalize proper names and acronyms that always call for upper case
letters.)  This is the case convention we use in most GNU manuals'
indices.

If you don't see how to make an entry terse yet clear, make it longer
and clear---not terse and confusing.  If many of the entries are several
words long, the index may look better if you use a different convention:
to capitalize the first word of each entry.  But do not capitalize a
case-sensitive name such as a C or Lisp function name or a shell
command; that would be a spelling error.

Whichever case convention you use, please use it consistently!

Entries in indices other than the concept index are symbol names in
programming languages, or program names; these names are usually
case-sensitive, so use upper and lower case as required for them.

@cindex Index font types
By default, entries for a concept index are printed in a small roman
font and entries for the other indices are printed in a small
@code{@@code} font.  You may change the way part of an entry is
printed with the usual Texinfo commands, such as @code{@@file} for
file names (@pxref{Marking Text}), and @code{@@r} for the normal roman
font (@pxref{Fonts}).

@quotation Caution
Do not use a colon in an index entry.  In Info, a colon separates the
menu entry name from the node name, so a colon in the entry itself
confuses Info.  @xref{Menu Parts}, for more information about the
structure of a menu entry.
@end quotation


@node Combining Indices
@section Combining Indices
@cindex Combining indices
@cindex Indices, combining them

Sometimes you will want to combine two disparate indices such as
functions and concepts, perhaps because you have few enough entries
that a separate index would look silly.

You could put functions into the concept index by writing
@code{@@cindex} commands for them instead of @code{@@findex} commands,
and produce a consistent manual by printing the concept index with the
title `Function and Concept Index' and not printing the `Function
Index' at all; but this is not a robust procedure.  It works only if
your document is never included as part of another document that is
designed to have a separate function index; if your document were to
be included with such a document, the functions from your document and
those from the other would not end up together.  Also, to make your
function names appear in the right font in the concept index, you
would need to enclose every one of them between the braces of
@code{@@code}.

@menu
* syncodeindex::                How to merge two indices, using @code{@@code}
                                 font for the merged-from index.
* synindex::                    How to merge two indices, using the
                                 default font of the merged-to index.
@end menu

@node syncodeindex
@subsection @code{@@syncodeindex}
@findex syncodeindex

When you want to combine functions and concepts into one index, you
should index the functions with @code{@@findex} and index the concepts
with @code{@@cindex}, and use the @code{@@syncodeindex} command to
redirect the function index entries into the concept index.@refill

The @code{@@syncodeindex} command takes two arguments; they are the name
of the index to redirect, and the name of the index to redirect it to.
The template looks like this:@refill

@example
@@syncodeindex @var{from} @var{to}
@end example

@cindex Predefined names for indices
@cindex Two letter names for indices
@cindex Indices, two letter names
@cindex Names for indices
For this purpose, the indices are given two-letter names:@refill

@table @samp
@item cp
concept index
@item fn
function index
@item vr
variable index
@item ky
key index
@item pg
program index
@item tp
data type index
@end table

Write an @code{@@syncodeindex} command before or shortly after the
end-of-header line at the beginning of a Texinfo file.  For example,
to merge a function index with a concept index, write the
following:@refill

@example
@@syncodeindex fn cp
@end example

@noindent
This will cause all entries designated for the function index to merge
in with the concept index instead.@refill

To merge both a variables index and a function index into a concept
index, write the following:@refill

@example
@group
@@syncodeindex vr cp
@@syncodeindex fn cp
@end group
@end example

@cindex Fonts for indices
The @code{@@syncodeindex} command puts all the entries from the `from'
index (the redirected index) into the @code{@@code} font, overriding
whatever default font is used by the index to which the entries are
now directed.  This way, if you direct function names from a function
index into a concept index, all the function names are printed in the
@code{@@code} font as you would expect.@refill

@node synindex
@subsection @code{@@synindex}
@findex synindex

The @code{@@synindex} command is nearly the same as the
@code{@@syncodeindex} command, except that it does not put the
`from' index  entries into the @code{@@code} font; rather it puts
them in the roman font.  Thus, you use @code{@@synindex} when you
merge a concept index into a function index.@refill

@xref{Printing Indices & Menus}, for information about printing an index
at the end of a book or creating an index menu in an Info file.@refill


@node New Indices
@section Defining New Indices
@cindex Defining new indices
@cindex Indices, defining new
@cindex New index defining
@findex defindex
@findex defcodeindex

In addition to the predefined indices, you may use the
@code{@@defindex} and @code{@@defcodeindex} commands to define new
indices.  These commands create new indexing @@-commands with which
you mark index entries.  The @code{@@defindex} command is used like
this:

@example
@@defindex @var{name}
@end example

The name of an index should be a two letter word, such as @samp{au}.
For example:

@example
@@defindex au
@end example

This defines a new index, called the @samp{au} index.  At the same
time, it creates a new indexing command, @code{@@auindex}, that you
can use to make index entries.  Use this new indexing command just as
you would use a predefined indexing command.

For example, here is a section heading followed by a concept index
entry and two @samp{au} index entries.

@example
@@section Cognitive Semantics
@@cindex kinesthetic image schemas
@@auindex Johnson, Mark
@@auindex Lakoff, George
@end example

@noindent
(Evidently, @samp{au} serves here as an abbreviation for ``author''.)

In general, Texinfo constructs the new indexing command by
concatenating the name of the index with @samp{index}; thus, defining
an @samp{xy} index leads to the automatic creation of an
@code{@@xyindex} command.

Use the @code{@@printindex} command to print the index, as you do with
the predefined indices.  For example:

@example
@group
@@node Author Index
@@unnumbered Author Index

@@printindex au
@end group
@end example

The @code{@@defcodeindex} is like the @code{@@defindex} command,
except that, in the printed output, it prints entries in an
@code{@@code} font by default instead of a roman font.  

You should define new indices before the end-of-header line of a
Texinfo file, and (of course) before any @code{@@synindex} or
@code{@@syncodeindex} commands (@pxref{Texinfo File Header}).


@node Insertions
@chapter Special Insertions
@cindex Inserting special characters and symbols
@cindex Special insertions

Texinfo provides several commands for inserting characters that have
special meaning in Texinfo, such as braces, and for other graphic
elements that do not correspond to simple characters you can type.

@iftex
These are:

@itemize @bullet
@item @samp{@@} and braces and commas.
@item Whitespace within and around a sentence.
@item Accents.
@item Dots and bullets.
@item The @TeX{} logo and the copyright symbol.
@item The euro and pounds currency symbols.
@item The degrees symbol.
@item The minus sign.
@item Mathematical expressions.
@item Glyphs for evaluation, macros, errors, etc.
@item Footnotes.
@item Images.
@end itemize
@end iftex

@menu
* Atsign Braces Comma::         Inserting @@ and @{@} and ,.
* Inserting Quote Characters::  Inserting left and right quotes, in code.
* Inserting Space::             How to insert the right amount of space
                                 within a sentence.
* Inserting Accents::           How to insert accents and special characters.
* Inserting Quotation Marks::   How to insert quotation marks.
* Dots Bullets::                How to insert dots and bullets.
* TeX and copyright::           How to insert the @TeX{} logo
                                 and the copyright symbol.
* euro::                        How to insert the Euro currency symbol.
* pounds::                      How to insert the pounds currency symbol.
* textdegree::                  How to insert the degrees symbol.
* minus::                       How to insert a minus sign.
* geq leq::                     How to insert greater/less-than-or-equal signs.
* math::                        How to format a mathematical expression.
* Click Sequences::             Inserting GUI usage sequences.
* Glyphs::                      How to indicate results of evaluation,
                                 expansion of macros, errors, etc.
@end menu


@node Atsign Braces Comma
@section Inserting @@ and @{@} and @comma{}
@cindex Special characters, inserting
@cindex Commands to insert special characters

@samp{@@} and curly braces are special characters in Texinfo.  To insert
these characters so they appear in text, you must put an @samp{@@} in
front of these characters to prevent Texinfo from misinterpreting
them.

The comma `,' is a special character only in one uncommon context:
it separates arguments to commands that take multiple arguments.

@menu
* Inserting an Atsign::
* Inserting Braces::
* Inserting a Comma::
@end menu


@node Inserting an Atsign
@subsection Inserting `@@' with @code{@@@@}
@findex @@ @r{(literal @samp{@@})}
@cindex Inserting @@ @r{(literal @samp{@@})}

@code{@@@@} stands for a single @samp{@@} in either printed or Info
output.

Do not put braces after an @code{@@@@} command.


@node Inserting Braces
@subsection Inserting `@{' and `@}' with @code{@@@{} and @code{@@@}}
@cindex Braces, inserting
@findex @{ @r{(literal @samp{@{})}
@findex @} @r{(literal @samp{@}})}

@code{@@@{} stands for a single @samp{@{} in either printed or Info
output.

@code{@@@}} stands for a single @samp{@}} in either printed or Info
output.

Do not put braces after either an @code{@@@{} or an @code{@@@}}
command.


@node Inserting a Comma
@subsection Inserting `,' with @code{@@comma@{@}}
@cindex Commas, inserting
@findex comma

Ordinarily, a comma `,' is a normal character that can be simply typed
in your input where you need it.

However, Texinfo uses the comma as a special character in one uncommon
context: some commands, such as @code{@@acronym} (@pxref{acronym}) and
@code{@@xref} (@pxref{Cross References}), as well as user-defined
macros (@pxref{Defining Macros}), can take more than one argument.  In
these cases, the comma character is used to separate arguments.

Since a comma character would confuse Texinfo's parsing for these
commands, you must use the command @samp{@@comma@{@}} instead if you want
to pass an actual comma.  Here are some examples:

@example
@@acronym@{ABC, A Bizarre @@comma@{@}@}
@@xref@{Comma,, The @@comma@{@} symbol@}
@@mymac@{One argument@@comma@{@} containing a comma@}
@end example

Although @comma{} can be used nearly anywhere, there is no need for it
anywhere except in this unusual case.


@node Inserting Quote Characters
@section Inserting Quote Characters

@cindex Inserting quote characters
@cindex Quote characters, inserting

As explained in the early section on general Texinfo input conventions
(@pxref{Conventions}), Texinfo source files use the ASCII character
@code{`} (96 decimal) to produce a left quote (`), and ASCII @code{'}
(39 decimal) to produce a right quote (').  Doubling these input
characters (@code{``} and @code{''}) produces double quotes (`` and
'').  These are the conventions used by @TeX{}.

This works all right for text.  However, in examples of computer code,
readers are especially likely to cut and paste the text
verbatim---and, unfortunately, some document viewers will mangle these
characters.  (The free PDF reader @command{xpdf} works fine, but other
PDF readers, both free and nonfree, have problems.)

If this is a concern for your document, Texinfo provides two special
settings via @code{@@set}:

@table @code
@item @@set txicodequoteundirected
causes the output for the @code{'} character to be the undirected
single quote, like this:
@set txicodequoteundirected
@code{'}.
@clear txicodequoteundirected

@item @@set txicodequotebacktick
Cause the output for the @code{`} character to be the standalone grave
accent, like this:
@set txicodequotebacktick
@code{`}.
@clear txicodequotebacktick

@end table

@code{xyza`'bc}

If you want these settings for only part of the document,
@code{@@clear} will restore the normal behavior, as in
@code{@@clear@tie{}txicodequoteundirected}.

These settings affect @code{@@code}, @code{@@example}, and
@code{@@verbatim}; they do not affect @code{@@samp}.  (@xref{Useful
Highlighting}.)


@node Inserting Space
@section Inserting Space

@cindex Inserting space
@cindex Spacing, inserting
The following sections describe commands that control spacing of various
kinds within and after sentences.

@menu
* Not Ending a Sentence::       Sometimes a . doesn't end a sentence.
* Ending a Sentence::           Sometimes it does.
* Multiple Spaces::             Inserting multiple spaces.
* frenchspacing::               Specifying end-of-sentence spacing.
* dmn::                         How to format a dimension.
@end menu


@node Not Ending a Sentence
@subsection Not Ending a Sentence

@cindex Not ending a sentence
@cindex Sentence non-ending punctuation
@cindex Periods, inserting
Depending on whether a period or exclamation point or question mark is
inside or at the end of a sentence, less or more space is inserted after
a period in a typeset manual.  Since it is not always possible
to determine when a period ends a sentence and when it is used
in an abbreviation, special commands are needed in some circumstances.
Usually, Texinfo can guess how to handle periods, so you do not need to
use the special commands; you just enter a period as you would if you
were using a typewriter, which means you put two spaces after the
period, question mark, or exclamation mark that ends a sentence.

@findex <colon> @r{(suppress end-of-sentence space)}
Use the @code{@@:}@: command after a period, question mark,
exclamation mark, or colon that should not be followed by extra space.
For example, use @code{@@:}@: after periods that end abbreviations
which are not at the ends of sentences.

For example,

@example
foo vs.@@: bar
foo vs. bar
@end example

@noindent
@ifnottex
produces
@end ifnottex
@iftex
produces the following.  If you look carefully at this printed output,
you will see a little extraneous space after @samp{vs.}@: in the second
line.
@end iftex

@quotation
foo vs.@: bar @*
foo vs. bar
@end quotation

@noindent
@code{@@:} has no effect on the Info and HTML output.  In Docbook and
XML, the previous punctuation character (.?!:) is output as an entity
instead of as the normal character: @samp{&period; &quest; &excl;
&colon;}.  This gives further processors a chance to notice and not
add the usual extra space.

Do not put braces after @code{@@:} (or any non-alphabetic command).


@node Ending a Sentence
@subsection Ending a Sentence

@cindex Ending a Sentence
@cindex Sentence ending punctuation

@findex .  @r{(end of sentence)}
@findex ! @r{(end of sentence)}
@findex ? @r{(end of sentence)}
Use @code{@@.}@: instead of a period, @code{@@!}@: instead of an
exclamation point, and @code{@@?}@: instead of a question mark at the end
of a sentence that ends with a capital letter.  Otherwise, @TeX{}
will think the letter is an abbreviation and will not insert the correct
end-of-sentence spacing.  Here is an example:

@example
Give it to M.I.B. and to M.E.W@@.  Also, give it to R.J.C@@.
Give it to M.I.B. and to M.E.W.  Also, give it to R.J.C.
@end example

@noindent
@ifnottex
produces
@end ifnottex
@iftex
produces the following.  If you look carefully at this printed output,
you will see a little more whitespace after the @samp{W} in the first
line.
@end iftex

@quotation
Give it to M.I.B. and to M.E.W@.  Also, give it to R.J.C@.@*
Give it to M.I.B. and to M.E.W.  Also, give it to R.J.C.
@end quotation

In the Info file output, @code{@@.}@: is equivalent to a simple
@samp{.}; likewise for @code{@@!}@: and @code{@@?}@:.

The meanings of @code{@@:} and @code{@@.}@: in Texinfo are designed to
work well with the Emacs sentence motion commands (@pxref{Sentences,,,
emacs, The GNU Emacs Manual}).

Do not put braces after any of these commands.


@node Multiple Spaces
@subsection Multiple Spaces

@cindex Multiple spaces
@cindex Whitespace, inserting
@cindex Space, inserting horizontal
@findex <space>
@findex <tab>
@findex <newline>

Ordinarily, @TeX{} collapses multiple whitespace characters (space, tab,
and newline) into a single space.  Info output, on the other hand,
preserves whitespace as you type it, except for changing a newline into
a space; this is why it is important to put two spaces at the end of
sentences in Texinfo documents.

Occasionally, you may want to actually insert several consecutive
spaces, either for purposes of example (what your program does with
multiple spaces as input), or merely for purposes of appearance in
headings or lists.  Texinfo supports three commands:
@code{@@@kbd{SPACE}}, @code{@@@kbd{TAB}}, and @code{@@@kbd{NL}}, all of
which insert a single space into the output.  (Here,
@code{@@@kbd{SPACE}} represents an @samp{@@} character followed by a
space, i.e., @samp{@@ }, and @kbd{TAB} and @kbd{NL} represent the tab
character and end-of-line, i.e., when @samp{@@} is the last character on
a line.)

For example,
@example
Spacey@@ @@ @@ @@
example.
@end example

@noindent produces

@example
Spacey@ @ @ @
example.
@end example

Other possible uses of @code{@@@kbd{SPACE}} have been subsumed by
@code{@@multitable} (@pxref{Multi-column Tables}).

Do not follow any of these commands with braces.

To produce a non-breakable space, see @ref{tie, @code{@@tie}}.


@node frenchspacing
@subsection @code{@@frenchspacing} @var{val}: Control sentence spacing
@findex frenchspacing
@cindex French spacing
@cindex Sentences, spacing after
@cindex Space, after sentences

In American typography, it is traditional and correct to put extra
space at the end of a sentence, after a semi-colon, and so on.  This
is the default in Texinfo.  In French typography (and many others),
this extra space is wrong; all spaces are uniform.

Therefore Texinfo provides the @code{@@frenchspacing} command to
control the spacing after punctuation.  It reads the rest of the line
as its argument, which must be the single word @samp{on} or @samp{off}
(always these words, regardless of the language) of the document.
Here is an example:

@example
@@frenchspacing on
This is text. Two sentences. Three sentences. French spacing.

@@frenchspacing off
This is text. Two sentences. Three sentences. Non-French spacing.
@end example

@noindent produces (there will be no difference in Info):

@frenchspacing on
This is text. Two sentences. Three sentences. French spacing.

@frenchspacing off
This is text. Two sentences. Three sentences. Non-French spacing.

@code{@@frenchspacing} mainly affects the printed output, including
the output after @code{@@.}, @code{@@!}, and @code{@@?} (@pxref{Ending
a Sentence}).

In Info, usually space characters in the input are written unaltered
to the output, and @code{@@frenchspacing} does not change this.  It
does change the one case where @command{makeinfo} outputs a space on
its own: when a sentence ends at a newline in the source.  Here's an
example:

@example
Some sentence.
Next sentence.
@end example

@noindent produces in Info output, with @code{@@frenchspacing off}
(the default), two spaces between the sentences:

@example
Some sentence.  Next sentence.
@end example

@noindent With @code{@@frenchspacing on}, @command{makeinfo} outputs
only a single space:

@example
Some sentence. Next sentence.
@end example

@code{@@frenchspacing} has no effect on the HTML or Docbook output;
for XML, it outputs a transliteration of itself (@pxref{Output
Formats}).


@node dmn
@subsection @code{@@dmn}@{@var{dimension}@}: Format a Dimension
@cindex Thin space between number, dimension
@cindex Dimension formatting
@cindex Format a dimension
@findex dmn

At times, you may want to write @samp{12@dmn{pt}} or
@samp{8.5@dmn{in}} with little or no space between the number and the
abbreviation for the dimension.  You can use the @code{@@dmn} command
to do this.  On seeing the command, @TeX{} inserts just enough space
for proper typesetting; the Info formatting commands insert no space
at all, since the Info file does not require it.

To use the @code{@@dmn} command, write the number and then follow it
immediately, with no intervening space, by @code{@@dmn}, and then by
the dimension within braces.  For example,

@example
A4 paper is 8.27@@dmn@{in@} wide.
@end example

@noindent
produces

@quotation
A4 paper is 8.27@dmn{in} wide.
@end quotation

Not everyone uses this style.  Some people prefer @w{@samp{8.27 in.@@:}}
or @w{@samp{8.27 inches}} to @samp{8.27@@dmn@{in@}} in the Texinfo file.
In these cases, however, the formatters may insert a line break between
the number and the dimension, so use @code{@@w} (@pxref{w}).  Also, if
you write a period after an abbreviation within a sentence, you should
write @samp{@@:} after the period to prevent @TeX{} from inserting extra
whitespace, as shown here.  @xref{Not Ending a Sentence}.


@node Inserting Accents
@section Inserting Accents

@cindex Inserting accents
@cindex Accents, inserting
@cindex Floating accents, inserting

Here is a table with the commands Texinfo provides for inserting
floating accents.  They all need an argument, the character to accent,
which can either be given in braces as usual (@code{@@'@{e@}}), or, as
a special case, the braces can be omitted, in which case the argument
is the next character (@code{@@'e}).  This is to make the source as
convenient as possible to type and read, since accented characters are
very common in some languages.

If the command is alphabetic, such as @code{@@dotaccent}, then there
must be a space between the command name and argument if braces are
not used.  If the command is non-alphabetic, such as @code{@@'}, then
there must @emph{not} be a space; the argument is the very next
character.

Exception: the argument to @code{@@tieaccent} must be enclosed in
braces (since it is two characters instead of one).

@findex documentencoding
To get the true accented characters output in Info, not just the ASCII
transliterations, it is necessary to specify @code{@@documentencoding}
with an encoding which supports the required characters
(@pxref{documentencoding,,@code{@@documentencoding}}).  In this case,
you can also use non-ASCII (e.g., pre-accented) characters in the
source file.

@findex " @r{(umlaut accent)}
@cindex Umlaut accent
@findex ' @r{(umlaut accent)}
@cindex Acute accent
@findex = @r{(macron accent)}
@cindex Macron accent
@findex ^ @r{(circumflex accent)}
@cindex Circumflex accent
@findex ` @r{(grave accent)}
@cindex Grave accent
@findex ~ @r{(tilde accent)}
@cindex Tilde accent
@findex , @r{(cedilla accent)}
@cindex Cedilla accent
@findex dotaccent
@cindex Dot accent
@findex H @r{(Hungarian umlaut accent)}
@cindex Hungarian umlaut accent
@findex ringaccent
@cindex Ring accent
@findex tieaccent
@cindex Tie-after accent
@findex u @r{(breve accent)}
@cindex Breve accent
@findex ubaraccent
@cindex Underbar accent
@findex udotaccent
@cindex Underdot accent
@findex v @r{(check accent)}
@cindex Hacek accent
@cindex Check accent
@cindex Caron accent
@multitable {@t{@@questiondown@{@}}} {Output} {hacek/check/caron accent}
@headitem Command           @tab Output         @tab What
@item @t{@@"o}              @tab @"o            @tab umlaut accent
@item @t{@@'o}              @tab @'o            @tab acute accent
@item @t{@@,@{c@}}          @tab @,{c}          @tab cedilla accent
@item @t{@@=o}              @tab @=o            @tab macron/overbar accent
@item @t{@@^o}              @tab @^o            @tab circumflex accent
@item @t{@@`o}              @tab @`o            @tab grave accent
@item @t{@@~o}              @tab @~o            @tab tilde accent
@item @t{@@dotaccent@{o@}}  @tab @dotaccent{o}  @tab overdot accent
@item @t{@@H@{o@}}          @tab @H{o}          @tab long Hungarian umlaut
@item @t{@@ringaccent@{o@}} @tab @ringaccent{o} @tab ring accent
@item @t{@@tieaccent@{oo@}} @tab @tieaccent{oo} @tab tie-after accent
@item @t{@@u@{o@}}          @tab @u{o}          @tab breve accent
@item @t{@@ubaraccent@{o@}} @tab @ubaraccent{o} @tab underbar accent
@item @t{@@udotaccent@{o@}} @tab @udotaccent{o} @tab underdot accent
@item @t{@@v@{o@}}          @tab @v{o}          @tab hacek/check/caron accent
@end multitable

This table lists the Texinfo commands for inserting other characters
commonly used in languages other than English.

@findex questiondown
@cindex @questiondown{}
@findex exclamdown
@cindex @exclamdown{}
@findex aa
@cindex @aa{}
@findex AA
@cindex @AA{}
@findex ae
@cindex @ae{}
@findex AE
@cindex @AE{}
@findex dotless
@cindex @dotless{i} (dotless i)
@cindex @dotless{j} (dotless j)
@cindex Dotless i, j
@findex l
@cindex @l{}
@findex L
@cindex @L{}
@findex o
@cindex @o{}
@findex O
@cindex @O{}
@findex oe
@cindex @oe{}
@findex OE
@cindex @OE{}
@cindex Romance ordinals
@cindex Ordinals, Romance
@cindex Feminine ordinal
@findex ordf
@cindex @ordf{}
@cindex Masculine ordinal
@findex ordm
@cindex @ordm{}
@findex ss
@cindex @ss{}
@cindex Es-zet
@cindex Sharp S
@cindex German S
@multitable {@t{@@questiondown@{@}}} {oe OE} {es-zet or sharp S}
@item @t{@@exclamdown@{@}}   @tab @exclamdown{}   @tab upside-down !
@item @t{@@questiondown@{@}} @tab @questiondown{} @tab upside-down ?
@item @t{@@aa@{@} @@AA@{@}}  @tab @aa{} @AA{}     @tab a,A with circle
@item @t{@@ae@{@} @@AE@{@}}  @tab @ae{} @AE{}     @tab ae,AE ligatures
@item @t{@@dotless@{i@}}     @tab @dotless{i}     @tab dotless i
@item @t{@@dotless@{j@}}     @tab @dotless{j}     @tab dotless j
@item @t{@@l@{@} @@L@{@}}    @tab @l{} @L{}       @tab suppressed-L,l
@item @t{@@o@{@} @@O@{@}}    @tab @o{} @O{}       @tab O,o with slash
@item @t{@@oe@{@} @@OE@{@}}  @tab @oe{} @OE{}     @tab oe,OE ligatures
@item @t{@@ordf@{@} @@ordm@{@}}  @tab @ordf{} @ordm{}     @tab Spanish ordinals
@item @t{@@ss@{@}}           @tab @ss{}           @tab es-zet or sharp S
@end multitable


@node Inserting Quotation Marks
@section Inserting Quotation Marks
@cindex Inserting quotation marks
@cindex Quotation marks, inserting

@cindex Quotation characters (`'), in source
Use doubled single-quote characters to begin and end quotations:
@w{@t{`@w{}`@dots{}'@w{}'}}.  @TeX{} converts two single quotes to
left- and right-hand doubled quotation marks,
@c this comes out as "like this" in Info, which is just confusing.
@iftex
``like this'',
@end iftex
and Info converts doubled single-quote characters to ASCII
double-quotes: @w{@t{`@w{}`@dots{}'@w{}'}} becomes @w{@t{"@dots{}"}}.

You may occasionally need to produce two consecutive single quotes;
for example, in documenting a computer language such as Maxima where
@t{'@w{}'} is a valid command.  You can do this with the input
@t{'@@w@{@}'}; the empty @code{@@w} command stops the combination into
the double-quote characters.

@cindex Unicode quotation characters
@cindex Grave accent, vs. left quote
The left quote character (@t{`}, ASCII code 96) used in Texinfo is a
grave accent in ANSI and ISO character set standards.  We use it as a
quote character because that is how @TeX{} is set up, by default.

Texinfo supports several other quotation marks used in languages other
than English.  Below is a table with the commands Texinfo provides for
inserting quotation marks.

@findex documentencoding
@cindex UTF-8
@cindex ISO 8859-15
@cindex Latin 9
@cindex ISO 8859-1
@cindex Latin 1
In order to get the symbols for the quotation marks in encoded Info
output, it is necessary to specify @code{@@documentencoding UTF-8}.
(@xref{documentencoding,,@code{@@documentencoding}}.)  Double
guillemets are also present in ISO 8859-1 (aka Latin@tie{}1) and ISO
8859-15 (aka Latin@tie{}9).

@cindex European Computer Modern fonts
@cindex EC fonts
The standard @TeX{} fonts support the usual quotation marks used in
English (the ones produced with single and doubled ASCII
single-quotes).  For the other quotation marks, @TeX{} uses European
Computer Modern (EC) fonts (@file{ecrm1000} and other variants).
These fonts are freely available, of course; you can download them
from @url{http://@/www.ctan.org/@/tex-archive/@/fonts/ec}, among other
places.

@cindex CM-Super fonts
The free EC fonts are bitmap fonts created with Metafont.  Especially
for on-line viewing, Type@tie{}1 (vector) versions of the fonts are
preferable; these are available in the CM-Super font package
(@url{http://@/www.ctan.org/@/tex-archive/@/fonts/@/ps-type1/@/cm-super}).

Both distributions include installation instructions.

@cindex Single quotation marks
@cindex Double quotation marks
@cindex Left quotation marks
@cindex Right quotation marks
@findex quotedblleft
@cindex ``
@findex quoteleft
@cindex `
@findex quotedblright
@cindex ''
@findex quoteright
@cindex '
@cindex Double low-9 quotation mark
@cindex Single low-9 quotation mark
@findex quotedblbase
@cindex @quotedblbase{} (double low-9 quotation mark)
@findex quotesinglbase
@cindex @quotesinglbase{} (single low-9 quotation mark)
@cindex Angle quotation marks
@cindex Guillemets
@cindex Guillemots
@cindex French quotation marks
@cindex Quotation marks, French
@cindex German quotation marks
@cindex Quotation marks, German
@cindex Double guillemets
@cindex Single guillemets
@cindex Double angle quotation marks
@cindex Single angle quotation marks
@cindex Left-pointing angle quotation marks
@cindex Right-pointing angle quotation marks
@cindex Double left-pointing angle quotation mark
@cindex Double right-pointing angle quotation mark
@cindex Single left-pointing angle quotation mark
@cindex Single right-pointing angle quotation mark
@findex guillemetleft
@findex guillemotleft
@cindex @guillemetleft{}
@findex guillemetright
@findex guillemotright
@cindex @guillemetright{}
@findex guilsinglleft
@cindex @guilsinglleft{}
@findex guilsinglright
@cindex @guilsinglright{}
@multitable {@t{@@quotedblright@{@} '@w{}'}} {Glyph} {Right-pointing double angle quotation mark (U+00BB)}
@headitem Command                    @tab Glyph             @tab Unicode name (point)
@item @verb{.@quotedblleft{} ``.}    @tab @quotedblleft{}   @tab Left double quotation mark (U+201C)
@item @verb{.@quotedblright{} ''.}   @tab @quotedblright{}  @tab Right double quotation mark (U+201D)
@item @verb{.@quoteleft{} `.}        @tab @quoteleft{}      @tab Left single quotation mark (U+2018)
@item @verb{.@quoteright{} '.}       @tab @quoteright{}     @tab Right single quotation mark (U+2019)
@item @t{@@quotedblbase@{@}}         @tab @quotedblbase{}   @tab Double low-9 quotation mark (U+201E)
@item @t{@@quotesinglbase@{@}}       @tab @quotesinglbase{} @tab Single low-9 quotation mark (U+201A)
@item @t{@@guillemetleft@{@}}        @tab @guillemetleft{}  @tab Left-pointing double angle quotation mark (U+00AB)
@item @t{@@guillemetright@{@}}       @tab @guillemetright{} @tab Right-pointing double angle quotation mark (U+00BB)
@item @t{@@guilsinglleft@{@}}        @tab @guilsinglleft{}  @tab Single left-pointing angle quotation mark (U+2039)
@item @t{@@guilsinglright@{@}}       @tab @guilsinglright{} @tab Single right-pointing angle quotation mark (U+203A)
@end multitable

For the double angle quotation marks, Adobe and @LaTeX{} glyph names
are also supported:  @code{@@guillemotleft} and
@code{@@guillemotright}.  These names are actually incorrect; a
``guillemot'' is a bird species (a type of auk).

Traditions for quotation mark usage vary to a great extent between
languages (@url{http://@/en.wikipedia.org/@/wiki/@/Quotation_mark%2C_non-English_usage@/#Overview}).
Texinfo does not provide commands for typesetting quotation marks
according to the numerous traditions.  Therefore, you have to choose
the commands appropriate for the language of your manual.  Sometimes
aliases (@pxref{alias,,@code{@@alias}}) can simplify the usage and
make the source code more readable.  For example, in German,
@code{@@quotedblbase} is used for the left double quote, and the right
double quote is actually @code{@@quotedblleft}, which is
counter-intuitive.  Thus, in this case the following aliases would be
convenient:

@example
@@alias lgqq = quotedblbase
@@alias rgqq = quotedblleft
@end example


@node Dots Bullets
@section Inserting Ellipsis and Bullets
@cindex Dots, inserting
@cindex Bullets, inserting
@cindex Ellipsis, inserting
@cindex Inserting ellipsis
@cindex Inserting dots
@cindex Special typesetting commands
@cindex Typesetting commands for dots, etc.

An @dfn{ellipsis} (a line of dots) is not typeset as a string of
periods, so a special command is used for ellipsis in Texinfo.  The
@code{@@bullet} command is special, too.  Each of these commands is
followed by a pair of braces, @samp{@{@}}, without any whitespace
between the name of the command and the braces.  (You need to use braces
with these commands because you can use them next to other text; without
the braces, the formatters would be confused.  @xref{Command Syntax, ,
@@-Command Syntax}, for further information.)@refill

@menu
* dots::                        How to insert dots @dots{}
* bullet::                      How to insert a bullet.
@end menu


@node dots
@subsection @code{@@dots}@{@} (@dots{}) and @code{@@enddots}@{@} (@enddots{})
@findex dots
@findex enddots
@cindex Inserting dots
@cindex Dots, inserting

Use the @code{@@dots@{@}} command to generate an ellipsis, which is
three dots in a row, appropriately spaced @dots{} like so.  Do
not simply write three periods in the input file; that would work for
the Info file output, but would produce the wrong amount of space
between the periods in the printed manual.

Similarly, the @code{@@enddots@{@}} command generates an
end-of-sentence ellipsis, which has different spacing afterwards,
@enddots{}  Look closely to see the difference.

@iftex
Here is an ellipsis: @dots{}
Here are three periods in a row: ...

In printed output, the three periods in a row are much closer together than
the dots in the ellipsis.
@end iftex


@node bullet
@subsection @code{@@bullet}@{@} (@bullet{})
@findex bullet

Use the @code{@@bullet@{@}} command to generate a large round dot, or
the closest possible thing to one.  In Info, an asterisk is used.@refill

Here is a bullet: @bullet{}

When you use @code{@@bullet} in @code{@@itemize}, you do not need to
type the braces, because @code{@@itemize} supplies them.
(@xref{itemize, , @code{@@itemize}}.)@refill


@node TeX and copyright
@section Inserting @TeX{} and Legal Symbols: @copyright{}, @registeredsymbol{}

The logo `@TeX{}' is typeset in a special fashion and it needs an
@@-command.  The copyright and registered symbols, `@copyright{}' and
`@registeredsymbol{}', is also special.  Each of these commands is
followed by a pair of braces, @samp{@{@}}, without any whitespace
between the name of the command and the braces.

@menu
* tex::                         The @TeX{} logos.
* copyright symbol::            The copyright symbol (c in a circle).
* registered symbol::           The registered symbol (R in a circle).
@end menu


@node tex
@subsection @code{@@TeX}@{@} (@TeX{}) and @code{@@LaTeX}@{@} (@LaTeX{})
@findex TeX
@findex LaTeX
@cindex Logos, @TeX{}
@cindex @TeX{} logo
@cindex @LaTeX{} logo

Use the @code{@@TeX@{@}} command to generate `@TeX{}'.  In a printed
manual, this is a special logo that is different from three ordinary
letters.  In Info, it just looks like @samp{TeX}.

Similarly, use the @code{@@LaTeX@{@}} command to generate `@LaTeX{}',
which is even more special in printed manuals (and different from the
incorrect @code{La@@TeX@{@}}.  In Info, the result is just
@samp{LaTeX}.  (@LaTeX{} is another macro package built on top of
@TeX{}, very loosely analogous to Texinfo in that it emphasizes
logical structure, but much (much) larger.)

The spelling of these commands are unusual among Texinfo commands in
that they use both uppercase and lowercase letters.


@node copyright symbol
@subsection @code{@@copyright@{@}} (@copyright{})
@findex copyright
@cindex Copyright symbol

Use the @code{@@copyright@{@}} command to generate the copyright
symbol, `@copyright{}'.  Where possible, this is a @samp{c}
inside a circle; in Info, this is @samp{(C)}.


@node registered symbol
@subsection @code{@@registeredsymbol@{@}} (@registeredsymbol{})
@findex registeredsymbol
@cindex Registered symbol

Use the @code{@@registeredsymbol@{@}} command to generate the
registered symbol, `@registeredsymbol{}'.  Where possible, this is an
@samp{R} inside a circle; in Info, this is @samp{(R)}.


@node euro
@section @code{@@euro}@{@} (@euro{}): Euro Currency Symbol
@findex euro
@cindex Euro symbol

Use the @code{@@euro@{@}} command to generate `@euro{}'.  Where
possible, this is the symbol for the Euro currency, invented as part
of the European economic unification.  In plain Info, it is the word
@samp{Euro }.  A trailing space is included in the text
transliteration since typically no space is desired after the symbol,
so it would be inappropriate to have a space in the source document.

Texinfo cannot magically synthesize support for the Euro symbol where
the underlying system (fonts, software, whatever) does not support
it.  Therefore, in many cases it is preferable to use the word
``Euro''.  (In banking circles, the abbreviation for the Euro is EUR.)

@cindex ISO 8859-15
@cindex Latin 9
In order to get the Euro symbol in encoded Info output, for example,
it is necessary to specify @code{@@documentencoding ISO-8859-15}.
(@xref{documentencoding,,@code{@@documentencoding}}.)  The Euro symbol
is in ISO 8859-15 (aka Latin@tie{}9), and is @emph{not} in the more
widely-used and supported ISO 8859-1 (Latin@tie{}1).

@pindex feymr10
@cindex Euro font
The Euro symbol does not exist in the standard @TeX{} fonts (which
were designed before the Euro was legislated into existence).
Therefore, @TeX{} uses an additional font, named @code{feymr10} (along
with other variables).  It is freely available, of course; you can
download it from @url{http://www.ctan.org/tex-archive/fonts/eurosym},
among other places.  The distribution includes installation
instructions.


@node pounds
@section @code{@@pounds}@{@} (@pounds{}): Pounds Sterling
@findex pounds
@cindex Pounds symbol

Use the @code{@@pounds@{@}} command to generate `@pounds{}'.  Where
possible, this is the symbol for the currency pounds sterling.  In
Info, it is a @samp{#}.


@node textdegree
@section @code{@@textdegree}@{@} (@textdegree{}): Degrees Symbol
@findex textdegree
@cindex Degree symbol

Use the @code{@@textdegree@{@}} command to generate `@textdegree{}'.
Where possible, this is the normal symbol for degrees.  In plain text
and Info output, it is an @samp{o}.


@node minus
@section @code{@@minus}@{@} (@minus{}): Inserting a Minus Sign
@findex minus
@cindex Minus sign

@cindex Em dash, compared to minus sign
@cindex Hyphen, compared to minus
Use the @code{@@minus@{@}} command to generate a minus sign.  In a
fixed-width font, this is a single hyphen, but in a proportional font,
the symbol is the customary length for a minus sign---a little longer
than a hyphen, shorter than an em-dash:

@display
@samp{@minus{}} is a minus sign generated with @samp{@@minus@{@}},

`-' is a hyphen generated with the character @samp{-},

`---' is an em-dash for text.
@end display

@noindent
In the fixed-width font used by Info, @code{@@minus@{@}} is the same
as a hyphen.

You should not use @code{@@minus@{@}} inside @code{@@code} or
@code{@@example} because the width distinction is not made in the
fixed-width font they use.

When you use @code{@@minus} to specify the mark beginning each entry in
an itemized list, you do not need to type the braces
(@pxref{itemize, , @code{@@itemize}}).


@node geq leq
@section @code{@@geq@{@}} (@geq{}) and @code{@@leq@{@}} (@leq{}): Inserting relations
@findex geq
@findex leq

Use the @code{@@geq@{@}} and @code{@@geq@{@}} commands to generate
greater-than-or-equal and less-than-equal-signs, `@geq{}' and
`@leq{}'.  In plain text and Info output, these are the ASCII
sequences @samp{>=} and @samp{<=}.  The 


@node math
@section @code{@@math}: Inserting Mathematical Expressions
@findex math
@cindex Mathematical expressions
@cindex Formulas, mathematical

You can write a short mathematical expression with the @code{@@math}
command.  Write the mathematical expression between braces, like this:

@example
@@math@{(a + b)(a + b) = a^2 + 2ab + b^2@}
@end example

@iftex
@noindent This produces the following in @TeX{}:

@display
@math{(a + b)(a + b) = a^2 + 2ab + b^2}
@end display

@noindent and the following in other formats:
@end iftex
@ifnottex
@noindent This produces the following in Info and HTML:
@end ifnottex

@example
(a + b)(a + b) = a^2 + 2ab + b^2
@end example

The @code{@@math} command has no special effect on the Info and HTML
output.  @command{makeinfo} expands any @code{@@}-commands as usual,
but it does not try to produce good mathematical formatting in any
way.

However, as far as the @TeX{} output is concerned, plain @TeX{}
mathematical commands are allowed in @code{@@math}, starting with
@samp{\}, and the plain @TeX{} math characters like @samp{^} and
@samp{_} are also recognized.  In essence, @code{@@math} drops you
into plain @TeX{} math mode.

This allows you to conveniently write superscripts and subscripts (as
in the above example), and also to use all the plain @TeX{} math
control sequences for symbols, functions, and so on, and thus get
proper formatting in the @TeX{} output, at least.

It's best to use @samp{\} instead of @samp{@@} for any such
mathematical commands; otherwise, @command{makeinfo} will complain.
On the other hand, input with matching (but unescaped) braces, such as
@samp{k_@{75@}}, is allowed inside @code{@@math}, although
@command{makeinfo} would complain about the bare braces in regular
input.

Here's an example:

@example
@@math@{\sin 2\pi \equiv \cos 3\pi@}
@end example

@iftex
@noindent which looks like this in @TeX{}:
@display
@math{\sin 2\pi \equiv \cos 3\pi}
@end display

@noindent and
@end iftex
@noindent which looks like the input in Info and HTML:
@example
\sin 2\pi \equiv \cos 3\pi
@end example

@findex \ @r{(literal \ in @code{@@math})}
Since @samp{\} is an escape character inside @code{@@math}, you can use
@code{@@\} to get a literal backslash (@code{\\} will work in @TeX{},
but you'd get the literal @samp{\\} in Info).  @code{@@\} is not
defined outside of @code{@@math}, since a @samp{\} ordinarily produces a
literal @samp{\}.

@cindex Displayed equations
@cindex Equations, displayed
For displayed equations, you must at present use @TeX{} directly
(@pxref{Raw Formatter Commands}).


@node Click Sequences
@section Click Sequences
@cindex Click sequences
@cindex Sequence of clicks
@cindex GUI click sequence

@findex clicksequence
When documenting graphical interfaces, it is necessary to describe
sequences such as `Click on @samp{File}, then choose @samp{Open}, then
@dots{}'.  Texinfo offers commands @code{@@clicksequence} and
@code{click} to represent this, typically used like this:

@example
@dots{} @@clicksequence@{File @@click@{@} Open@} @dots{}
@end example

@noindent
which produces:

@display
@dots{} @clicksequence{File @click{} Open} @dots{}
@end display

@findex click
@findex arrow
The @code{@@click} command produces a simple right arrow (@samp{->} in
Info) by default; this glyph is also available independently via the
command @code{@@arrow@{@}}.

@findex clickstyle
You can change the glyph produced by @code{@@click} with the command
@code{@@clickstyle}, which takes a command name as its single argument
on the rest of the line, much like @code{@@itemize} and friends
(@pxref{itemize,,@code{@@itemize}}).  The command should produce a
glyph, and the usual empty braces @samp{@{@}} are omitted.  Here's an
example:

@example
@@clickstyle @@result
@dots{} @@clicksequence@{File @@click@{@} Open@} @dots{}
@end example

@noindent
now produces:

@display
@clickstyle @result
@dots{} @clicksequence{File @click{} Open} @dots{}
@end display


@node Glyphs
@section Glyphs for Examples
@cindex Glyphs
@cindex Examples, glyphs for

In Texinfo, code is often illustrated in examples that are delimited
by @code{@@example} and @code{@@end example}, or by @code{@@lisp} and
@code{@@end lisp}.  In such examples, you can indicate the results of
evaluation or an expansion using @samp{@result{}} or
@samp{@expansion{}}.  Likewise, there are commands to insert glyphs
to indicate
printed output, error messages, equivalence of expressions, and the
location of point.

The glyph-insertion commands do not need to be used within an example, but
most often they are.  Every  glyph-insertion command is followed by a pair of
left- and right-hand braces.@refill

@menu
* Glyphs Summary::
* result::                      How to show the result of expression.
* expansion::                   How to indicate an expansion.
* Print Glyph::                 How to indicate printed output.
* Error Glyph::                 How to indicate an error message.
* Equivalence::                 How to indicate equivalence.
* Point Glyph::                 How to indicate the location of point.
@end menu


@node Glyphs Summary
@subsection Glyphs Summary

Here are the different glyph commands:@refill

@table @asis
@item @result{}
@code{@@result@{@}} points to the result of an expression.@refill

@item @expansion{}
@code{@@expansion@{@}} shows the results of a macro expansion.@refill

@item @print{}
@code{@@print@{@}} indicates printed output.@refill

@item @error{}
@code{@@error@{@}} indicates that the following text is an error
message.@refill

@item @equiv{}
@code{@@equiv@{@}} indicates the exact equivalence of two forms.@refill

@item @point{}
@code{@@point@{@}} shows the location of point.@refill
@end table

@menu
* result::
* expansion::
* Print Glyph::
* Error Glyph::
* Equivalence::
* Point Glyph::
@end menu


@node result
@subsection @code{@@result@{@}} (@result{}): Indicating Evaluation
@cindex Result of an expression
@cindex Indicating evaluation
@cindex Evaluation glyph
@cindex Value of an expression, indicating
@findex result

Use the @code{@@result@{@}} command to indicate the result of
evaluating an expression.@refill

@iftex
The @code{@@result@{@}} command is displayed as @samp{@result{}} in
the printed output and as @samp{=>} in other formats.
@end iftex
@ifnottex
The @code{@@result@{@}} command is displayed as @samp{@result{}} in
Info and HTML and as a true double stemmed arrow in the printed output.
@end ifnottex

Thus, the following,

@lisp
(cdr '(1 2 3))
    @result{} (2 3)
@end lisp

@noindent
may be read as ``@code{(cdr '(1 2 3))} evaluates to @code{(2 3)}''.


@node expansion
@subsection @code{@@expansion@{@}} (@expansion{}): Indicating an Expansion
@cindex Expansion, indicating
@cindex Macro expansion, indicating
@findex expansion

When an expression is a macro call, it expands into a new expression.
You can indicate the result of the expansion with the
@code{@@expansion@{@}} command.@refill

@iftex
The @code{@@expansion@{@}} command is displayed as @samp{@expansion{}}
in the printed output and as @samp{==>} in other formats.
@end iftex
@ifnottex
The @code{@@expansion@{@}} command is displayed as @samp{@expansion{}}
in Info and HTML, and as a long arrow with a flat base in the printed
output.
@end ifnottex

@need 700
For example, the following

@example
@group
@@lisp
(third '(a b c))
    @@expansion@{@} (car (cdr (cdr '(a b c))))
    @@result@{@} c
@@end lisp
@end group
@end example

@noindent
produces

@lisp
@group
(third '(a b c))
    @expansion{} (car (cdr (cdr '(a b c))))
    @result{} c
@end group
@end lisp

@noindent
which may be read as:

@quotation
@code{(third '(a b c))} expands to @code{(car (cdr (cdr '(a b c))))};
the result of evaluating the expression is @code{c}.
@end quotation

@noindent
Often, as in this case, an example looks better if the
@code{@@expansion@{@}} and @code{@@result@{@}} commands are indented.


@node Print Glyph
@subsection @code{@@print@{@}} (@print{}): Indicating Printed Output
@cindex Printed output, indicating
@findex print

Sometimes an expression will print output during its execution.  You
can indicate the printed output with the @code{@@print@{@}} command.@refill

@iftex
The @code{@@print@{@}} command is displayed as @samp{-|} in Info and
HTML and as @samp{@print{}} in the printed output.
@end iftex
@ifnottex
The @code{@@print@{@}} command is displayed as @samp{@print{}} in Info
and HTML and (similarly) as a horizontal dash butting against a
vertical bar in the printed output.
@end ifnottex

In the following example, the printed text is indicated with
@samp{@print{}}, and the value of the expression follows on the
last line.

@lisp
@group
(progn (print 'foo) (print 'bar))
    @print{} foo
    @print{} bar
    @result{} bar
@end group
@end lisp

@noindent
In a Texinfo source file, this example is written as follows:

@lisp
@group
@@lisp
(progn (print 'foo) (print 'bar))
    @@print@{@} foo
    @@print@{@} bar
    @@result@{@} bar
@@end lisp
@end group
@end lisp


@node Error Glyph
@subsection @code{@@error@{@}} (@error{}): Indicating an Error Message
@cindex Error message, indicating
@findex error

A piece of code may cause an error when you evaluate it.  You can
designate the error message with the @code{@@error@{@}} command.@refill

@iftex
The @code{@@error@{@}} command is displayed as @samp{error-->} in Info
and HTML and as @samp{@error{}} in the printed output.
@end iftex
@ifnottex
The @code{@@error@{@}} command is displayed as @samp{@error{}} in Info
and HTML and as the word `error' in a box in the printed output.
@end ifnottex

@need 700
Thus,

@example
@@lisp
(+ 23 'x)
@@error@{@} Wrong type argument: integer-or-marker-p, x
@@end lisp
@end example

@noindent
produces

@lisp
(+ 23 'x)
@error{} Wrong type argument: integer-or-marker-p, x
@end lisp

@noindent
This indicates that the following error message is printed
when you evaluate the expression:

@lisp
Wrong type argument: integer-or-marker-p, x
@end lisp

@samp{@error{}} itself is not part of the error message.


@node Equivalence
@subsection @code{@@equiv@{@}} (@equiv{}): Indicating Equivalence
@cindex Equivalence, indicating
@findex equiv

Sometimes two expressions produce identical results.  You can indicate the
exact equivalence of two forms with the @code{@@equiv@{@}} command.@refill

@iftex
The @code{@@equiv@{@}} command is displayed as @samp{==} in Info and
HTML and as @samp{@equiv{}} in the printed output.
@end iftex
@ifnottex
The @code{@@equiv@{@}} command is displayed as @samp{@equiv{}} in Info
and HTML and as a standard mathematical equivalence sign (three
parallel horizontal lines) in the printed output.
@end ifnottex

Thus,

@example
@@lisp
(make-sparse-keymap) @@equiv@{@} (list 'keymap)
@@end lisp
@end example

@noindent
produces

@lisp
(make-sparse-keymap) @equiv{} (list 'keymap)
@end lisp

@noindent
This indicates that evaluating @code{(make-sparse-keymap)} produces
identical results to evaluating @code{(list 'keymap)}.


@node Point Glyph
@subsection @code{@@point@{@}} (@point{}): Indicating Point in a Buffer
@cindex Point, indicating in a buffer
@findex point

Sometimes you need to show an example of text in an Emacs buffer.  In
such examples, the convention is to include the entire contents of the
buffer in question between two lines of dashes containing the buffer
name.@refill

You can use the @samp{@@point@{@}} command to show the location of point
in the text in the buffer.  (The symbol for point, of course, is not
part of the text in the buffer; it indicates the place @emph{between}
two characters where point is located.)@refill

@iftex
The @code{@@point@{@}} command is displayed as @samp{-!-} in Info and
HTML and as @samp{@point{}} in the printed output.
@end iftex
@ifnottex
The @code{@@point@{@}} command is displayed as @samp{@point{}} in Info
and HTML and as a small five pointed star in the printed
output.
@end ifnottex

The following example shows the contents of buffer @file{foo} before
and after evaluating a Lisp command to insert the word @code{changed}.@refill

@example
@group
---------- Buffer: foo ----------
This is the @point{}contents of foo.
---------- Buffer: foo ----------

@end group
@end example

@example
@group
(insert "changed ")
    @result{} nil
---------- Buffer: foo ----------
This is the changed @point{}contents of foo.
---------- Buffer: foo ----------

@end group
@end example

In a Texinfo source file, the example is written like this:@refill

@example
@@example
---------- Buffer: foo ----------
This is the @@point@{@}contents of foo.
---------- Buffer: foo ----------

(insert "changed ")
    @@result@{@} nil
---------- Buffer: foo ----------
This is the changed @@point@{@}contents of foo.
---------- Buffer: foo ----------
@@end example
@end example


@node Breaks
@chapter Forcing and Preventing Breaks
@cindex Forcing line and page breaks
@cindex Making line and page breaks
@cindex Preventing line and page breaks

@cindex Line breaks
Usually, a Texinfo file is processed both by @TeX{} and by one of the
Info formatting commands.  Line, paragraph, or page breaks sometimes
occur in the `wrong' place in one or other form of output.  You must
ensure that text looks right both in the printed manual and in the
Info file.

@cindex White space, excessive
@cindex Page breaks
For example, in a printed manual, page breaks may occur awkwardly in
the middle of an example; to prevent this, you can hold text together
using a grouping command that keeps the text from being split across
two pages.  Conversely, you may want to force a page break where none
would occur normally.  Fortunately, problems like these do not often
arise.  When they do, use the break, break prevention, or pagination
commands.

@menu
* Break Commands::              Summary of break-related commands.
* Line Breaks::                 Forcing line breaks.
* - and hyphenation::           Helping @TeX{} with hyphenation points.
* allowcodebreaks::             Controlling line breaks within @@code text.
* w::                           Preventing unwanted line breaks in text.
* tie::                         Inserting an unbreakable but varying space.
* sp::                          Inserting blank lines.
* page::                        Forcing the start of a new page.
* group::                       Preventing unwanted page breaks.
* need::                        Another way to prevent unwanted page breaks.
@end menu


@node Break Commands
@section Break Commands

The break commands create or allow line and paragraph breaks:

@table @code
@item @@*
Force a line break.

@item @@sp @var{n}
Skip @var{n} blank lines.

@item @@-
Insert a discretionary hyphen.

@item @@hyphenation@{@var{hy-phen-a-ted words}@}
Define hyphen points in @var{hy-phen-a-ted words}.
@end table

These commands hold text together on a single line:

@table @code
@item @@w@{@var{text}@}
Prevent @var{text} from being split and hyphenated across two lines.
@item @@tie@{@}
Insert a normal interword space at which a line break may not occur.
@end table
@iftex
@sp 1
@end iftex

The pagination commands apply only to printed output, since Info
files do not have pages.

@table @code
@item @@page
Start a new page in the printed manual.

@item @@group
Hold text together that must appear on one printed page.

@item @@need @var{mils}
Start a new printed page if not enough space on this one.
@end table


@node Line Breaks
@section @code{@@*} and @code{@@/}: Generate and Allow Line Breaks
@findex * @r{(force line break)}
@findex / @r{(allow line break)}
@cindex Line breaks
@cindex Breaks in a line
@cindex Force line break
@cindex Allow line break

The @code{@@*} command forces a line break in both the printed manual and
in Info.  The @code{@@/} command allows a line break (printed manual only).

Here is an example with @code{@@*}:

@example
This line @@* is broken @@*in two places.
@end example

@noindent produces

@example
@group
This line
is broken
in two places.
@end group
@end example

The @code{@@/} command can be useful within a url
(@pxref{uref,,@code{@@uref}}), which tend to be long and are otherwise
unbreakable.  For example:

@example
The official Texinfo home page is on the GNU web site:
@@uref@{http://www.gnu.org/@@/software/@@/gnu/@@/texinfo@}.
@end example

@noindent produces

@display
The official Texinfo home page is on the GNU web site:
@uref{http://www.gnu.org/@/software/@/gnu/@/texinfo}.
@end display

@noindent Without the @code{@@/} commands, @TeX{} would have nowhere to
break the line.  @code{@@/} has no effect in the online output.


@node - and hyphenation
@section @code{@@-} and @code{@@hyphenation}: Helping @TeX{} Hyphenate

@findex - @r{(discretionary hyphen)}
@findex hyphenation
@cindex Hyphenation, helping @TeX{} do
@cindex Fine-tuning, and hyphenation

Although @TeX{}'s hyphenation algorithm is generally pretty good, it
does miss useful hyphenation points from time to time.  (Or, far more
rarely, insert an incorrect hyphenation.)  So, for documents with an
unusual vocabulary or when fine-tuning for a printed edition, you may
wish to help @TeX{} out.  Texinfo supports two commands for this:

@table @code
@item @@-
Insert a discretionary hyphen, i.e., a place where @TeX{} can (but does
not have to) hyphenate.  This is especially useful when you notice an
overfull hbox is due to @TeX{} missing a hyphenation (@pxref{Overfull
hboxes}).  @TeX{} will not insert any hyphenation points itself into a
word containing @code{@@-}.

@item @@hyphenation@{@var{hy-phen-a-ted words}@}
Tell @TeX{} how to hyphenate @var{hy-phen-a-ted words}.  As shown, you
put a @samp{-} at each hyphenation point.  For example:
@example
@@hyphenation@{man-u-script man-u-scripts@}
@end example
@noindent @TeX{} only uses the specified hyphenation points when the
words match exactly, so give all necessary variants, such as plurals.
@end table

Info, HTML, and other non-@TeX{} output is not hyphenated, so none of
these commands have any effect there.


@node allowcodebreaks
@section @code{@@allowcodebreaks}: Control Line Breaks in @code{@@code}

@findex allowcodebreaks
@cindex Breaks, within @code{@@code}
@cindex -, breakpoint within @code{@@code}
@cindex Hyphen, breakpoint within @code{@@code}
@cindex Dash, breakpoint within @code{@@code}
@cindex _, breakpoint within @code{@@code}
@cindex Underscore, breakpoint within @code{@@code}

Ordinarily, @TeX{} will consider breaking lines at @samp{-} and
@samp{_} characters within @code{@@code} and related commands
(@pxref{code,,@code{@@code}}), more or less as if they were ``empty''
hyphenation points.

This is necessary as many manuals, especially for Lisp-family
languages, must document very long identifiers.  On the other hand,
other manuals don't have this problems, and you may not wish to allow
a line break at the underscore in, for example, @code{SIZE_MAX}, or
even worse, after any of the four underscores in @code{__typeof__}.

So Texinfo provides this command:

@example
@@allowcodebreaks false
@end example

@noindent to prevent @TeX{} from breaking at @samp{-} or @samp{_} within
@code{@@code}.  You can go back to allowing such breaks with
@code{@@allowcodebreaks true}.  Write these commands on lines by
themselves.

These commands can be given anywhere in the document.  For example,
you may have just one problematic paragraph where you need to turn off
the breaks, but want them in general, or vice versa.

This command has no effect in Info, HTML, and other non-@TeX{} output.


@node w
@section @code{@@w}@{@var{text}@}: Prevent Line Breaks
@findex w @r{(prevent line break)}
@cindex Line breaks, preventing

@code{@@w@{@var{text}@}} outputs @var{text} and prohibits line breaks
within @var{text}, for both @TeX{} and @command{makeinfo}.

@cindex Non-breakable space, fixed
@cindex Unbreakable space, fixed
Thus, you can use @code{@@w} to produce a non-breakable space, fixed at
the width of a normal interword space:

@example
@@w@{ @} @@w@{ @} @@w@{ @} indentation.
@end example

@noindent produces:

@display
@w{ } @w{ } @w{ } indentation.
@end display

The space from @code{@@w@{@w{ }@}}, as well as being non-breakable,
also will not stretch or shrink.  Sometimes that is what you want, for
instance if you're doing manual indenting.  However, usually you want
a normal interword space that does stretch and shrink (in the printed
output); see the @code{@@tie} command in the next section.

@cindex Hyphenation, preventing
You can also use the @code{@@w} command to prevent @TeX{} from
automatically hyphenating a long name or phrase that happens to fall
near the end of a line.  @command{makeinfo} does not ever hyphenate
words.

@cindex Keyword expansion, preventing
@cindex Version control keywords, preventing expansion of
@cindex $Id expansion, preventing
You can also use @code{@@w} to avoid unwanted keyword expansion in
source control systems.  For example, to literally write @t{@w{$}Id$}
in your document, use @code{@@w@{$@}Id$}.


@node tie
@section @code{@@tie@{@}}: Inserting an Unbreakable Space
@findex tie @r{(unbreakable interword space)}
@cindex Tied space
@cindex Non-breakable space, variable
@cindex Unbreakable space, variable

The @code{@@tie@{@}} command produces a normal interword space at which
a line break may not occur.  Always write it with following (empty)
braces, as usual for commands used within a paragraph.  Here's an
example:

@example
@@TeX@{@} was written by Donald E.@@tie@{@}Knuth.
@end example

@noindent produces:

@display
@TeX{} was written by Donald E.@tie{}Knuth.
@end display

There are two important differences between @code{@@tie@{@}} and
@code{@@w@{@w{ }@}}:

@itemize
@item
The space produced by @code{@@tie@{@}} will stretch and shrink slightly
along with the normal interword spaces in the paragraph; the space
produced by @code{@@w@{@w{ }@}} will not vary.

@item
@code{@@tie@{@}} allows hyphenation of the surrounding words, while
@code{@@w@{@w{ }@}} inhibits hyphenation of those words (for @TeX{}nical
reasons, namely that it produces an @samp{\hbox}).

@end itemize


@node sp
@section @code{@@sp} @var{n}: Insert Blank Lines
@findex sp @r{(line spacing)}
@cindex Space, inserting vertical
@cindex Blank lines
@cindex Line spacing

A line beginning with and containing only @code{@@sp @var{n}}
generates @var{n} blank lines of space in both the printed manual and
the Info file.  @code{@@sp} also forces a paragraph break.  For
example,

@example
@@sp 2
@end example

@noindent
generates two blank lines.

The @code{@@sp} command is most often used in the title page.@refill

@ignore
@c node br, page, sp, Breaks
@comment  node-name,  next,  previous,  up
@c section @code{@@br}: Generate Paragraph Breaks
@findex br @r{(paragraph breaks)}
@cindex Paragraph breaks
@cindex Breaks in a paragraph

The @code{@@br} command forces a paragraph break.  It inserts a blank
line.  You can use the command within or at the end of a line.  If
used within a line, the @code{@@br@{@}} command must be followed by
left and right braces (as shown here) to mark the end of the
command.@refill

@need 700
For example,

@example
@group
This line @@br@{@}contains and is ended by paragraph breaks@@br
and is followed by another line.
@end group
@end example

@noindent
produces

@example
@group
This line

contains and is ended by paragraph breaks

and is followed by another line.
@end group
@end example

The @code{@@br} command is seldom used.
@end ignore


@node page
@section @code{@@page}: Start a New Page
@cindex Page breaks
@findex page

A line containing only @code{@@page} starts a new page in a printed
manual.  The command has no effect on Info files since they are not
paginated.  An @code{@@page} command is often used in the @code{@@titlepage}
section of a Texinfo file to start the copyright page.


@node group
@comment  node-name,  next,  previous,  up
@section @code{@@group}: Prevent Page Breaks
@cindex Group (hold text together vertically)
@cindex Holding text together vertically
@cindex Vertically holding text together
@findex group

The @code{@@group} command (on a line by itself) is used inside an
@code{@@example} or similar construct to begin an unsplittable vertical
group, which will appear entirely on one page in the printed output.
The group is terminated by a line containing only @code{@@end group}.
These two lines produce no output of their own, and in the Info file
output they have no effect at all.@refill

@c Once said that these environments
@c turn off vertical spacing between ``paragraphs''.
@c Also, quotation used to work, but doesn't in texinfo-2.72
Although @code{@@group} would make sense conceptually in a wide
variety of contexts, its current implementation works reliably only
within @code{@@example} and variants, and within @code{@@display},
@code{@@format}, @code{@@flushleft} and @code{@@flushright}.
@xref{Quotations and Examples}.  (What all these commands have in
common is that each line of input produces a line of output.)  In
other contexts, @code{@@group} can cause anomalous vertical
spacing.@refill

@need 750
This formatting requirement means that you should write:

@example
@group
@@example
@@group
@dots{}
@@end group
@@end example
@end group
@end example

@noindent
with the @code{@@group} and @code{@@end group} commands inside the
@code{@@example} and @code{@@end example} commands.

The @code{@@group} command is most often used to hold an example
together on one page.  In this Texinfo manual, more than 100 examples
contain text that is enclosed between @code{@@group} and @code{@@end
group}.

If you forget to end a group, you may get strange and unfathomable
error messages when you run @TeX{}.  This is because @TeX{} keeps
trying to put the rest of the Texinfo file onto the one page and does
not start to generate error messages until it has processed
considerable text.  It is a good rule of thumb to look for a missing
@code{@@end group} if you get incomprehensible error messages in
@TeX{}.@refill

@node need
@comment  node-name,  next,  previous,  up
@section @code{@@need @var{mils}}: Prevent Page Breaks
@cindex Need space at page bottom
@findex need

A line containing only @code{@@need @var{n}} starts
a new page in a printed manual if fewer than @var{n} mils (thousandths
of an inch) remain on the current page.  Do not use
braces around the argument @var{n}.  The @code{@@need} command has no
effect on Info files since they are not paginated.@refill

@need 800
This paragraph is preceded by an @code{@@need} command that tells
@TeX{} to start a new page if fewer than 800 mils (eight-tenths
inch) remain on the page.  It looks like this:@refill

@example
@group
@@need 800
This paragraph is preceded by @dots{}
@end group
@end example

The @code{@@need} command is useful for preventing orphans (single
lines at the bottoms of printed pages).@refill


@node Definition Commands
@chapter Definition Commands
@cindex Definition commands

The @code{@@deffn} command and the other @dfn{definition commands}
enable you to describe functions, variables, macros, commands, user
options, special forms and other such artifacts in a uniform
format.@refill

In the Info file, a definition causes the entity
category---`Function', `Variable', or whatever---to appear at the
beginning of the first line of the definition, followed by the
entity's name and arguments.  In the printed manual, the command
causes @TeX{} to print the entity's name and its arguments on the left
margin and print the category next to the right margin.  In both
output formats, the body of the definition is indented.  Also, the
name of the entity is entered into the appropriate index:
@code{@@deffn} enters the name into the index of functions,
@code{@@defvr} enters it into the index of variables, and so
on (@pxref{Predefined Indices}).

A manual need not and should not contain more than one definition for
a given name.  An appendix containing a summary should use
@code{@@table} rather than the definition commands.@refill

@menu
* Def Cmd Template::            Writing descriptions using definition commands.
* Def Cmd Continuation Lines::  Continuing the heading over source lines.
* Optional Arguments::          Handling optional and repeated arguments.
* deffnx::                      Group two or more `first' lines.
* Def Cmds in Detail::          Reference for all the definition commands.
* Def Cmd Conventions::         Conventions for writing definitions.
* Sample Function Definition::  An example.
@end menu


@node Def Cmd Template
@section The Template for a Definition
@cindex Definition template
@cindex Template for a definition

The @code{@@deffn} command is used for definitions of entities that
resemble functions.  To write a definition using the @code{@@deffn}
command, write the @code{@@deffn} command at the beginning of a line
and follow it on the same line by the category of the entity, the name
of the entity itself, and its arguments (if any).  Then write the body
of the definition on succeeding lines.  (You may embed examples in the
body.)  Finally, end the definition with an @code{@@end deffn} command
written on a line of its own.

The other definition commands follow the same format: a line with the
@code{@@def@dots{}} command and whatever arguments are appropriate for
that command; the body of the definition; and a corresponding
@code{@@end} line.

The template for a definition looks like this:

@example
@group
@@deffn @var{category} @var{name} @var{arguments}@dots{}
@var{body-of-definition}
@@end deffn
@end group
@end example

@need 700
@noindent
For example,

@example
@group
@@deffn Command forward-word count
This command moves point forward @@var@{count@} words
(or backward if @@var@{count@} is negative). @dots{}
@@end deffn
@end group
@end example

@noindent
produces

@quotation
@deffn Command forward-word count
This command moves point forward @var{count} words
(or backward if @var{count} is negative). @dots{}
@end deffn
@end quotation

Capitalize the category name like a title.  If the name of the
category contains spaces, as in the phrase `Interactive Command',
enclose it in braces.  For example:

@example
@group
@@deffn @{Interactive Command@} isearch-forward
@dots{}
@@end deffn
@end group
@end example

@noindent
Otherwise, the second word will be mistaken for the name of the
entity.  As a general rule, when any of the arguments in the heading
line @emph{except} the last one are more than one word, you need to
enclose them in braces.  This may also be necessary if the text
contains commands, for example, @samp{@{declaraci@@'on@}} if you are
writing in Spanish.

Some of the definition commands are more general than others.  The
@code{@@deffn} command, for example, is the general definition command
for functions and the like---for entities that may take arguments.
When you use this command, you specify the category to which the
entity belongs.  Three predefined, specialized variations
(@code{@@defun}, @code{@@defmac}, and @code{@@defspec}) specify the
category for you: ``Function'', ``Macro'', and ``Special Form''
respectively.  (In Lisp, a special form is an entity much like a
function.)  Similarly, the general @code{@@defvr} command is
accompanied by several specialized variations for describing
particular kinds of variables.

@xref{Sample Function Definition}, for a detailed example of a
function definition, including the use of @code{@@example} inside the
definition.

@cindex Macros in definition commands
Unfortunately, due to implementation difficulties, macros are not expanded
in @code{@@deffn} and all the other definition commands.


@node Def Cmd Continuation Lines
@section Definition Command Continuation Lines
@cindex Continuation lines in definition commands
@cindex Definition command headings, continuing
@cindex @samp{@@} as continuation in definition commands

The heading line of a definition command can get very long.
Therefore, Texinfo has a special syntax allowing them to be continued
over multiple lines of the source file: a lone @samp{@@} at the end of
each line to be continued.  Here's an example:

@example
@@defun fn-name @@
  arg1 arg2 arg3
This is the basic continued defun.
@@end defun
@end example

@noindent produces:

@defun fn-name @
  arg1 arg2 arg3
This is the basic continued defun.
@end defun

@noindent
As you can see, the continued lines are combined, as if they had been
typed on one source line.

Although this example only shows a one-line continuation,
continuations may extend over any number of lines; simply put an
@code{@@} at the end of each line to be continued.

The @code{@@} character does not have to be the last character on the
physical line: whitespace is allowed (and ignored) afterwards.

@cindex Whitespace, collapsed around continuations
@cindex Collapsing whitespace around continuations
In general, any number of spaces or tabs around the @code{@@}
continuation character, both on the line with the @code{@@} and on the
continued line, are collapsed into a single space.  There is one
exception: the Texinfo processors will not fully collapse whitespace
around a continuation inside braces.  For example:

@example
@@deffn @{Category @@
  Name@} @dots{}
@end example

@noindent The output (not shown) has excess space between `Category'
and `Name'.  In this case, simply elide any unwanted whitespace in
your input, or put the continuation @code{@@} outside braces.

@code{@@} does not (currently) function as a continuation character in
@emph{any} other context.  Ordinarily, @samp{@@} followed by a
whitespace character (space, tab, newline) produces a normal interword
space (@pxref{Multiple Spaces}).


@node Optional Arguments
@section Optional and Repeated Arguments
@cindex Optional and repeated arguments
@cindex Repeated and optional arguments
@cindex Arguments, repeated and optional
@cindex Syntax, optional & repeated arguments
@cindex Meta-syntactic chars for arguments

Some entities take optional or repeated arguments, which may be
specified by a distinctive glyph that uses square brackets and
ellipses.  For @w{example}, a special form often breaks its argument list
into separate arguments in more complicated ways than a
straightforward function.

@c This is consistent with Emacs Lisp Reference manual
An argument enclosed within square brackets is optional.
Thus, [@var{optional-arg}] means that @var{optional-arg} is optional.
An argument followed by an ellipsis is optional
and may be repeated more than once.
@c This is consistent with Emacs Lisp Reference manual
Thus, @var{repeated-args}@samp{@dots{}} stands for zero or more
arguments.  Parentheses are used when several arguments are grouped
into additional levels of list structure in Lisp.

Here is the @code{@@defspec} line of an example of an imaginary
special form:

@quotation
@defspec foobar (@var{var} [@var{from} @var{to} [@var{inc}]]) @var{body}@dots{}
@end defspec
@tex
\vskip \parskip
@end tex
@end quotation

@noindent
In this example, the arguments @var{from} and @var{to} are optional,
but must both be present or both absent.  If they are present,
@var{inc} may optionally be specified as well.  These arguments are
grouped with the argument @var{var} into a list, to distinguish them
from @var{body}, which includes all remaining elements of the
form.@refill

In a Texinfo source file, this @code{@@defspec} line is written like
this (except it would not be split over two lines, as it is in this
example).@refill

@example
@group
@@defspec foobar (@@var@{var@} [@@var@{from@} @@var@{to@}
    [@@var@{inc@}]]) @@var@{body@}@@dots@{@}
@end group
@end example

@noindent
The function is listed in the Command and Variable Index under
@samp{foobar}.@refill


@node deffnx
@section Two or More `First' Lines
@cindex Two `First' Lines for @code{@@deffn}
@cindex Grouping two definitions together
@cindex Definitions grouped together
@findex deffnx

To create two or more `first' or header lines for a definition, follow
the first @code{@@deffn} line by a line beginning with @code{@@deffnx}.
The @code{@@deffnx} command works exactly like @code{@@deffn}
except that it does not generate extra vertical white space between it
and the preceding line.@refill

@need 1000
For example,

@example
@group
@@deffn @{Interactive Command@} isearch-forward
@@deffnx @{Interactive Command@} isearch-backward
These two search commands are similar except @dots{}
@@end deffn
@end group
@end example

@noindent
produces

@deffn {Interactive Command} isearch-forward
@deffnx {Interactive Command} isearch-backward
These two search commands are similar except @dots{}
@end deffn

Each definition command has an `x' form: @code{@@defunx},
@code{@@defvrx}, @code{@@deftypefunx}, etc.

The `x' forms work similarly to @code{@@itemx} (@pxref{itemx}).


@node Def Cmds in Detail
@section The Definition Commands

Texinfo provides more than a dozen definition commands, all of which
are described in this section.@refill

The definition commands automatically enter the name of the entity in
the appropriate index: for example, @code{@@deffn}, @code{@@defun},
and @code{@@defmac} enter function names in the index of functions;
@code{@@defvr} and @code{@@defvar} enter variable names in the index
of variables.@refill

Although the examples that follow mostly illustrate Lisp, the commands
can be used for other programming languages.@refill

@menu
* Functions Commands::          Commands for functions and similar entities.
* Variables Commands::          Commands for variables and similar entities.
* Typed Functions::             Commands for functions in typed languages.
* Typed Variables::             Commands for variables in typed languages.
* Data Types::                  The definition command for data types.
* Abstract Objects::            Commands for object-oriented programming.
@end menu

@node Functions Commands
@subsection Functions and Similar Entities

This section describes the commands for describing functions and similar
entities:@refill

@table @code
@findex deffn
@item @@deffn @var{category} @var{name} @var{arguments}@dots{}
The @code{@@deffn} command is the general definition command for
functions, interactive commands, and similar entities that may take
arguments.  You must choose a term to describe the category of entity
being defined; for example, ``Function'' could be used if the entity is
a function.  The @code{@@deffn} command is written at the beginning of a
line and is followed on the same line by the category of entity being
described, the name of this particular entity, and its arguments, if
any.  Terminate the definition with @code{@@end deffn} on a line of its
own.@refill

@need 750
For example, here is a definition:

@example
@group
@@deffn Command forward-char nchars
Move point forward @@var@{nchars@} characters.
@@end deffn
@end group
@end example

@noindent
This shows a rather terse definition for a ``command'' named
@code{forward-char} with one argument, @var{nchars}.

@code{@@deffn} and prints argument names such as @var{nchars} in slanted
type in the printed output, because we think of these names as
metasyntactic variables---they stand for the actual argument values.
Within the text of the description, however, write an argument name
explicitly with @code{@@var} to refer to the value of the argument.
In the example above, we used @samp{@@var@{nchars@}} in this way.

In the unusual case when an argument name contains @samp{--}, or
another character sequence which is treated specially
(@pxref{Conventions}), use @code{@@var} around the argument.  This
causes the name to be printed in slanted typewriter, instead of the
regular slanted font, exactly as input.
@c except for ?` and !`, but we won't explain that.

The template for @code{@@deffn} is:

@example
@group
@@deffn @var{category} @var{name} @var{arguments}@dots{}
@var{body-of-definition}
@@end deffn
@end group
@end example

@findex defun
@item @@defun @var{name} @var{arguments}@dots{}
The @code{@@defun} command is the definition command for functions.
@code{@@defun} is equivalent to @samp{@@deffn Function @dots{}}.
Terminate the definition with @code{@@end defun} on a line of its own.
Thus, the template is:

@example
@group
@@defun @var{function-name} @var{arguments}@dots{}
@var{body-of-definition}
@@end defun
@end group
@end example

@findex defmac
@item @@defmac @var{name} @var{arguments}@dots{}
The @code{@@defmac} command is the definition command for macros.
@code{@@defmac} is equivalent to @samp{@@deffn Macro @dots{}} and
works like @code{@@defun}.

@findex defspec
@item @@defspec @var{name} @var{arguments}@dots{}
The @code{@@defspec} command is the definition command for special
forms.  (In Lisp, a special form is an entity much like a function,
@pxref{Special Forms,,, elisp, GNU Emacs Lisp Reference Manual}.)
@code{@@defspec} is equivalent to @samp{@@deffn @{Special Form@}
@dots{}} and works like @code{@@defun}.
@end table

All these commands create entries in the index of functions.


@node Variables Commands
@subsection Variables and Similar Entities

Here are the commands for defining variables and similar
entities:@refill

@table @code
@findex defvr
@item @@defvr @var{category} @var{name}
The @code{@@defvr} command is a general definition command for
something like a variable---an entity that records a value.  You must
choose a term to describe the category of entity being defined; for
example, ``Variable'' could be used if the entity is a variable.
Write the @code{@@defvr} command at the beginning of a line and
follow it on the same line by the category of the entity and the
name of the entity.

Capitalize the category name like a title.  If the name of the category
contains spaces, as in the name ``User Option'', enclose it in braces.
Otherwise, the second word will be mistaken for the name of the entity.
For example,

@example
@group
@@defvr @{User Option@} fill-column
This buffer-local variable specifies
the maximum width of filled lines.
@dots{}
@@end defvr
@end group
@end example

Terminate the definition with @code{@@end defvr} on a line of its
own.@refill

The template is:

@example
@group
@@defvr @var{category} @var{name}
@var{body-of-definition}
@@end defvr
@end group
@end example

@code{@@defvr} creates an entry in the index of variables for @var{name}.

@findex defvar
@item @@defvar @var{name}
The @code{@@defvar} command is the definition command for variables.
@code{@@defvar} is equivalent to @samp{@@defvr Variable
@dots{}}.@refill

@need 750
For example:

@example
@group
@@defvar kill-ring
@dots{}
@@end defvar
@end group
@end example

The template is:

@example
@group
@@defvar @var{name}
@var{body-of-definition}
@@end defvar
@end group
@end example

@code{@@defvar} creates an entry in the index of variables for
@var{name}.@refill

@findex defopt
@item @@defopt @var{name}
@cindex User options, marking
The @code{@@defopt} command is the definition command for @dfn{user
options}, i.e., variables intended for users to change according to
taste; Emacs has many such (@pxref{Variables,,, emacs, The GNU Emacs
Manual}).  @code{@@defopt} is equivalent to @samp{@@defvr @{User
Option@} @dots{}} and works like @code{@@defvar}.  It creates an entry
in the index of variables.
@end table


@node Typed Functions
@subsection Functions in Typed Languages

The @code{@@deftypefn} command and its variations are for describing
functions in languages in which you must declare types of variables and
functions, such as C and C++.

@table @code
@findex deftypefn
@item @@deftypefn @var{category} @var{data-type} @var{name} @var{arguments}@dots{}
The @code{@@deftypefn} command is the general definition command for
functions and similar entities that may take arguments and that are
typed.  The @code{@@deftypefn} command is written at the beginning of
a line and is followed on the same line by the category of entity
being described, the type of the returned value, the name of this
particular entity, and its arguments, if any.@refill

@need 800
@noindent
For example,

@example
@group
@@deftypefn @{Library Function@} int foobar
  (int @@var@{foo@}, float @@var@{bar@})
@dots{}
@@end deftypefn
@end group
@end example

@need 1000
@noindent
(where the text before the ``@dots{}'', shown above as two lines, would
actually be a single line in a real Texinfo file) produces the following
in Info:

@smallexample
@group
-- Library Function: int foobar (int FOO, float BAR)
@dots{}
@end group
@end smallexample
@iftex

In a printed manual, it produces:

@quotation
@deftypefn {Library Function} int foobar (int @var{foo}, float @var{bar})
@dots{}
@end deftypefn
@end quotation
@end iftex

This means that @code{foobar} is a ``library function'' that returns an
@code{int}, and its arguments are @var{foo} (an @code{int}) and
@var{bar} (a @code{float}).@refill

Since in typed languages, the actual names of the arguments are
typically scattered among data type names and keywords, Texinfo cannot
find them without help.  You can either (a)@tie{}write everything
as straight text, and it will be printed in slanted type; (b)@tie{}use
@code{@@var} for the variable names, which will uppercase the
variable names in Info and use the slanted typewriter font in printed
output; (c)@tie{}use @code{@@var} for the variable names and
@code{@@code} for the type names and keywords, which will be dutifully
obeyed.

The template for @code{@@deftypefn} is:@refill

@example
@group
@@deftypefn @var{category} @var{data-type} @var{name} @var{arguments} @dots{}
@var{body-of-description}
@@end deftypefn
@end group
@end example

@noindent
Note that if the @var{category} or @var{data type} is more than one
word then it must be enclosed in braces to make it a single argument.@refill

If you are describing a procedure in a language that has packages,
such as Ada, you might consider using @code{@@deftypefn} in a manner
somewhat contrary to the convention described in the preceding
paragraphs.  For example:

@example
@group
@@deftypefn stacks private push @@
       (@@var@{s@}:in out stack; @@
       @@var@{n@}:in integer)
@dots{}
@@end deftypefn
@end group
@end example

@noindent
(The @code{@@deftypefn} arguments are shown using continuations
(@pxref{Def Cmd Continuation Lines}), but could be on a single line in
a real Texinfo file.)

In this instance, the procedure is classified as belonging to the
package @code{stacks} rather than classified as a `procedure' and its
data type is described as @code{private}.  (The name of the procedure
is @code{push}, and its arguments are @var{s} and @var{n}.)@refill

@code{@@deftypefn} creates an entry in the index of functions for
@var{name}.

@item @@deftypefun @var{data-type} @var{name} @var{arguments}@dots{}
@findex deftypefun
The @code{@@deftypefun} command is the specialized definition command
for functions in typed languages.  The command is equivalent to
@samp{@@deftypefn Function @dots{}}.  The template is:

@example
@group
@@deftypefun @var{type} @var{name} @var{arguments}@dots{}
@var{body-of-description}
@@end deftypefun
@end group
@end example

@code{@@deftypefun} creates an entry in the index of functions for
@var{name}.

@end table


@node Typed Variables
@subsection Variables in Typed Languages

Variables in typed languages are handled in a manner similar to
functions in typed languages.  @xref{Typed Functions}.  The general
definition command @code{@@deftypevr} corresponds to
@code{@@deftypefn} and the specialized definition command
@code{@@deftypevar} corresponds to @code{@@deftypefun}.@refill

@table @code
@findex deftypevr
@item @@deftypevr @var{category} @var{data-type} @var{name}
The @code{@@deftypevr} command is the general definition command for
something like a variable in a typed language---an entity that records
a value.  You must choose a term to describe the category of the
entity being defined; for example, ``Variable'' could be used if the
entity is a variable.@refill

The @code{@@deftypevr} command is written at the beginning of a line
and is followed on the same line by the category of the entity
being described, the data type, and the name of this particular
entity.@refill

@need 800
@noindent
For example:

@example
@group
@@deftypevr @{Global Flag@} int enable
@dots{}
@@end deftypevr
@end group
@end example

@noindent
produces the following in Info:

@example
@group
-- Global Flag: int enable
@dots{}
@end group
@end example
@iftex

@noindent
and the following in a printed manual:

@quotation
@deftypevr {Global Flag} int enable
@dots{}
@end deftypevr
@end quotation
@end iftex

@need 800
The template is:

@example
@@deftypevr @var{category} @var{data-type} @var{name}
@var{body-of-description}
@@end deftypevr
@end example

@findex deftypevar
@item @@deftypevar @var{data-type} @var{name}
The @code{@@deftypevar} command is the specialized definition command
for variables in typed languages.  @code{@@deftypevar} is equivalent
to @samp{@@deftypevr Variable @dots{}}.  The template is:

@example
@group
@@deftypevar @var{data-type} @var{name}
@var{body-of-description}
@@end deftypevar
@end group
@end example
@end table

These commands create entries in the index of variables.

@node Data Types
@subsection Data Types

Here is the command for data types:@refill

@table @code
@findex deftp
@item @@deftp @var{category} @var{name} @var{attributes}@dots{}
The @code{@@deftp} command is the generic definition command for data
types.  The command is written at the beginning of a line and is
followed on the same line by the category, by the name of the type
(which is a word like @code{int} or @code{float}), and then by names of
attributes of objects of that type.  Thus, you could use this command
for describing @code{int} or @code{float}, in which case you could use
@code{data type} as the category.  (A data type is a category of
certain objects for purposes of deciding which operations can be
performed on them.)@refill

In Lisp, for example,  @dfn{pair} names a particular data
type, and an object of that type has two slots called the
@sc{car} and the @sc{cdr}.  Here is how you would write the first line
of a definition of @code{pair}.@refill

@example
@group
@@deftp @{Data type@} pair car cdr
@dots{}
@@end deftp
@end group
@end example

@need 950
The template is:

@example
@group
@@deftp @var{category} @var{name-of-type} @var{attributes}@dots{}
@var{body-of-definition}
@@end deftp
@end group
@end example

@code{@@deftp} creates an entry in the index of data types.
@end table


@node Abstract Objects
@subsection Object-Oriented Programming

@cindex Object-oriented programming

Here are the commands for formatting descriptions about abstract
objects, such as are used in object-oriented programming.  A class is
a defined type of abstract object.  An instance of a class is a
particular object that has the type of the class.  An instance
variable is a variable that belongs to the class but for which each
instance has its own value.

@menu
* Variables: Object-Oriented Variables.
* Methods: Object-Oriented Methods.
@end menu


@node Object-Oriented Variables
@subsubsection Object-Oriented Variables

@cindex Variables, object-oriented

These commands allow you to define different sorts of variables in
object-oriented programming languages.

@table @code
@item @@defcv @var{category} @var{class} @var{name}
@findex defcv
The @code{@@defcv} command is the general definition command for
variables associated with classes in object-oriented programming.  The
@code{@@defcv} command is followed by three arguments: the category of
thing being defined, the class to which it belongs, and its
name.  For instance:

@example
@group
@@defcv @{Class Option@} Window border-pattern
@dots{}
@@end defcv
@end group
@end example

@noindent produces:
@defcv {Class Option} Window border-pattern
@dots{}
@end defcv

@code{@@defcv} creates an entry in the index of variables.

@item @@deftypecv @var{category} @var{class} @var{data-type} @var{name}
@findex deftypecv
The @code{@@deftypecv} command is the definition command for typed
class variables in object-oriented programming.  It is analogous to
@code{@@defcv} with the addition of the @var{data-type} parameter to
specify the type of the instance variable.  Ordinarily, the data type
is a programming language construct that should be marked with
@code{@@code}. For instance:

@example
@group
@@deftypecv @{Class Option@} Window @@code@{int@} border-pattern
@dots{}
@@end deftypecv
@end group
@end example

@noindent produces:

@deftypecv {Class Option} Window @code{int} border-pattern
@dots{}
@end deftypecv

@code{@@deftypecv} creates an entry in the index of variables.

@item @@defivar @var{class} @var{name}
@findex defivar
The @code{@@defivar} command is the definition command for instance
variables in object-oriented programming.  @code{@@defivar} is
equivalent to @samp{@@defcv @{Instance Variable@} @dots{}}.  For
instance:

@example
@group
@@defivar Window border-pattern
@dots{}
@@end defivar
@end group
@end example

@noindent produces:

@defivar Window border-pattern
@dots{}
@end defivar

@code{@@defivar} creates an entry in the index of variables.

@item @@deftypeivar @var{class} @var{data-type} @var{name}
@findex deftypeivar
The @code{@@deftypeivar} command is the definition command for typed
instance variables in object-oriented programming.  It is analogous to
@code{@@defivar} with the addition of the @var{data-type} parameter to
specify the type of the instance variable.  Ordinarily, the data type
is a programming language construct that should be marked with
@code{@@code}. For instance:

@example
@group
@@deftypeivar Window @@code@{int@} border-pattern
@dots{}
@@end deftypeivar
@end group
@end example

@noindent produces:

@deftypeivar Window @code{int} border-pattern
@dots{}
@end deftypeivar

@code{@@deftypeivar} creates an entry in the index of variables.

@end table

@node Object-Oriented Methods
@subsubsection Object-Oriented Methods

@cindex Methods, object-oriented

These commands allow you to define different sorts of function-like
entities resembling methods in object-oriented programming languages.
These entities take arguments, as functions do, but are associated with
particular classes of objects.

@table @code

@findex defop
@item @@defop @var{category} @var{class} @var{name} @var{arguments}@dots{}
The @code{@@defop} command is the general definition command for these
method-like entities.

For example, some systems have constructs called @dfn{wrappers} that
are associated with classes as methods are, but that act more like
macros than like functions.  You could use @code{@@defop Wrapper} to
describe one of these.@refill

Sometimes it is useful to distinguish methods and @dfn{operations}.
You can think of an operation as the specification for a method.
Thus, a window system might specify that all window classes have a
method named @code{expose}; we would say that this window system
defines an @code{expose} operation on windows in general.  Typically,
the operation has a name and also specifies the pattern of arguments;
all methods that implement the operation must accept the same
arguments, since applications that use the operation do so without
knowing which method will implement it.@refill

Often it makes more sense to document operations than methods.  For
example, window application developers need to know about the
@code{expose} operation, but need not be concerned with whether a
given class of windows has its own method to implement this operation.
To describe this operation, you would write:@refill

@example
@@defop Operation windows expose
@end example

The @code{@@defop} command is written at the beginning of a line and
is followed on the same line by the overall name of the category of
operation, the name of the class of the operation, the name of the
operation, and its arguments, if any.@refill

The template is:
@example
@group
@@defop @var{category} @var{class} @var{name} @var{arguments}@dots{}
@var{body-of-definition}
@@end defop
@end group
@end example

@code{@@defop} creates an entry, such as `@code{expose} on
@code{windows}', in the index of functions.@refill

@findex deftypeop
@item @@deftypeop @var{category} @var{class} @var{data-type} @var{name} @var{arguments}@dots{}
The @code{@@deftypeop} command is the definition command for typed
operations in object-oriented programming.  It is similar to
@code{@@defop} with the addition of the @var{data-type} parameter to
specify the return type of the method.  @code{@@deftypeop} creates an
entry in the index of functions.

@item @@defmethod @var{class} @var{name} @var{arguments}@dots{}
@findex defmethod
The @code{@@defmethod} command is the definition command for methods
in object-oriented programming.  A method is a kind of function that
implements an operation for a particular class of objects and its
subclasses.
@ignore
@c ADR: Who cares?!?
@c KB: Oh, I don't know, I think this info is crucial!
In the Lisp Machine, methods actually were functions, but
they were usually defined with @code{defmethod}.
@end ignore

@code{@@defmethod} is equivalent to @samp{@@defop Method @dots{}}.
The command is written at the beginning of a line and is followed by
the name of the class of the method, the name of the method, and its
arguments, if any.@refill

@noindent
For example:
@example
@group
@@defmethod @code{bar-class} bar-method argument
@dots{}
@@end defmethod
@end group
@end example

@noindent
illustrates the definition for a method called @code{bar-method} of
the class @code{bar-class}.  The method takes an argument.

@code{@@defmethod} creates an entry in the index of functions.

@item @@deftypemethod @var{class} @var{data-type} @var{name} @var{arguments}@dots{}
@findex defmethod
The @code{@@deftypemethod} command is the definition command for methods
in object-oriented typed languages, such as C++ and Java.  It is similar
to the @code{@@defmethod} command with the addition of the
@var{data-type} parameter to specify the return type of the method.
@code{@@deftypemethod} creates an entry in the index of functions.

@end table


@node Def Cmd Conventions
@section Conventions for Writing Definitions
@cindex Definition conventions
@cindex Conventions for writing definitions

When you write a definition using @code{@@deffn}, @code{@@defun}, or
one of the other definition commands, please take care to use
arguments that indicate the meaning, as with the @var{count} argument
to the @code{forward-word} function.  Also, if the name of an argument
contains the name of a type, such as @var{integer}, take care that the
argument actually is of that type.@refill


@node Sample Function Definition
@section A Sample Function Definition
@cindex Function definitions
@cindex Command definitions
@cindex Macro definitions
@cindex Sample function definition

A function definition uses the @code{@@defun} and @code{@@end defun}
commands.  The name of the function follows immediately after the
@code{@@defun} command and it is followed, on the same line, by the
parameter list.@refill

Here is a definition from @ref{Calling Functions,,, elisp, The GNU Emacs
Lisp Reference Manual}.

@quotation
@defun apply function &rest arguments
@code{apply} calls @var{function} with @var{arguments}, just
like @code{funcall} but with one difference: the last of
@var{arguments} is a list of arguments to give to
@var{function}, rather than a single argument.  We also say
that this list is @dfn{appended} to the other arguments.

@code{apply} returns the result of calling @var{function}.
As with @code{funcall}, @var{function} must either be a Lisp
function or a primitive function; special forms and macros
do not make sense in @code{apply}.

@example
(setq f 'list)
    @result{} list
(apply f 'x 'y 'z)
@error{} Wrong type argument: listp, z
(apply '+ 1 2 '(3 4))
    @result{} 10
(apply '+ '(1 2 3 4))
    @result{} 10

(apply 'append '((a b c) nil (x y z) nil))
    @result{} (a b c x y z)
@end example

An interesting example of using @code{apply} is found in the description
of @code{mapcar}.@refill
@end defun
@end quotation

@need 1200
In the Texinfo source file, this example looks like this:

@example
@group
@@defun apply function &rest arguments
@@code@{apply@} calls @@var@{function@} with
@@var@{arguments@}, just like @@code@{funcall@} but with one
difference: the last of @@var@{arguments@} is a list of
arguments to give to @@var@{function@}, rather than a single
argument.  We also say that this list is @@dfn@{appended@}
to the other arguments.
@end group

@group
@@code@{apply@} returns the result of calling
@@var@{function@}.  As with @@code@{funcall@},
@@var@{function@} must either be a Lisp function or a
primitive function; special forms and macros do not make
sense in @@code@{apply@}.
@end group

@group
@@example
(setq f 'list)
    @@result@{@} list
(apply f 'x 'y 'z)
@@error@{@} Wrong type argument: listp, z
(apply '+ 1 2 '(3 4))
    @@result@{@} 10
(apply '+ '(1 2 3 4))
    @@result@{@} 10

(apply 'append '((a b c) nil (x y z) nil))
    @@result@{@} (a b c x y z)
@@end example
@end group

@group
An interesting example of using @@code@{apply@} is found
in the description of @@code@{mapcar@}.
@@end defun
@end group
@end example

@noindent
In this manual, this function is listed in the Command and Variable
Index under @code{apply}.@refill

Ordinary variables and user options are described using a format like
that for functions except that variables do not take arguments.


@node Conditionals
@chapter Conditionally Visible Text
@cindex Conditionally visible text
@cindex Text, conditionally visible
@cindex Visibility of conditional text
@cindex If text conditionally visible

The @dfn{conditional commands} allow you to use different text for
different output formats, or for general conditions that you define.
For example, you can use them to specify different text for the
printed manual and the Info output.

The conditional commands comprise the following categories.

@itemize @bullet
@item
Commands specific to an output format (Info, @TeX{}, HTML, @dots{}).

@item
Commands specific to any output format @emph{other} than a given
one (not Info, not @TeX{}, @dots{}).

@item
`Raw' formatter text for any output format, passed straight
through with no interpretation of @@-commands.

@item
Format-independent variable substitutions, and testing if a variable
is set or clear.

@end itemize

@menu
* Conditional Commands::        Text for a given format.
* Conditional Not Commands::    Text for any format other than a given one.
* Raw Formatter Commands::      Using raw formatter commands.
* set clear value::             Variable tests and substitutions.
* Conditional Nesting::         Using conditionals inside conditionals.
@end menu


@node Conditional Commands
@section Conditional Commands

Texinfo has an @code{@@if@var{format}} environment for each output
format, to allow conditional inclusion of text for a particular output
format.

@findex ifinfo
@code{@@ifinfo} begins segments of text that should be ignored by
@TeX{} when it typesets the printed manual, and by @command{makeinfo}
when not producing Info output.  The segment of text appears only in
the Info file and, for historical compatibility, the plain text
output.

@findex ifdocbook
@findex ifhtml
@findex ifplaintext
@findex iftex
@findex ifxml
The environments for the other formats are analogous:

@table @code
@item @@ifdocbook @dots{} @@end ifdocbook
Text to appear only in the Docbook output.

@item @@ifhtml @dots{} @@end ifhtml
Text to appear only in the HTML output.

@item @@ifplaintext @dots{} @@end ifplaintext
Text to appear only in the plain text output.

@item @@iftex @dots{} @@end iftex
Text to appear only in the printed manual.

@item @@ifxml @dots{} @@end ifxml
Text to appear only in the XML output.
@end table

The @code{@@if@dots{}} and @code{@@end if@dots{}} commands must appear
on lines by themselves in your source file.

Here is an example showing all these conditionals:

@example
@@iftex
This text will appear only in the printed manual.
@@end iftex
@@ifinfo
However, this text will appear only in Info and plain text.
@@end ifinfo
@@ifhtml
And this text will only appear in HTML.
@@end ifhtml
@@ifplaintext
Whereas this text will only appear in plain text.
@@end ifplaintext
@@ifxml
Notwithstanding that this will only appear in XML.
@@end ifxml
@@ifdocbook
Nevertheless, this will only appear in Docbook.
@@end ifdocbook
@end example

@noindent
The preceding example produces the following line:

@iftex
This text will appear only in the printed manual.
@end iftex
@ifinfo
However, this text will appear only in Info and plain text.
@end ifinfo
@ifhtml
And this text will only appear in HTML.
@end ifhtml
@ifplaintext
Whereas this text will only appear in plain text.
@end ifplaintext
@ifxml
Notwithstanding that this will only appear in XML.
@end ifxml
@ifdocbook
Nevertheless, this will only appear in Docbook.
@end ifdocbook

@noindent
Notice that you only see one of the input lines, depending on which
version of the manual you are reading.


@node Conditional Not Commands
@section Conditional Not Commands
@findex ifnotdocbook
@findex ifnothtml
@findex ifnotinfo
@findex ifnotplaintext
@findex ifnottex
@findex ifnotxml

You can specify text to be included in any output format @emph{other}
than a given one with the @code{@@ifnot@dots{}} environments:

@example
@@ifnotdocbook @dots{} @@end ifnotdocbook
@@ifnothtml @dots{} @@end ifnothtml
@@ifnotinfo @dots{} @@end ifnotinfo
@@ifnotplaintext @dots{} @@end ifnotplaintext
@@ifnottex @dots{} @@end ifnottex
@@ifnotxml @dots{} @@end ifnotxml
@end example

@noindent
The @code{@@ifnot@dots{}} command and the @code{@@end} command must
appear on lines by themselves in your actual source file.

If the output file is being made in the given format, the
region is @emph{ignored}.  Otherwise, it is included.

There is one exception (for historical compatibility):
@code{@@ifnotinfo} text is omitted for both Info and plain text
output, not just Info.  To specify text which appears only in Info and
not in plain text, use @code{@@ifnotplaintext}, like this:

@example
@@ifinfo
@@ifnotplaintext
This will be in Info, but not plain text.
@@end ifnotplaintext
@@end ifinfo
@end example

The regions delimited by these commands are ordinary Texinfo source as
with @code{@@iftex}, not raw formatter source as with @code{@@tex}
(@pxref{Raw Formatter Commands}).


@node Raw Formatter Commands
@section Raw Formatter Commands
@cindex Raw formatter commands
@cindex @TeX{} commands, using ordinary
@cindex Ordinary @TeX{} commands, using
@cindex Commands using raw @TeX{}
@cindex Docbook, including raw
@cindex HTML, including raw
@cindex XML, including raw
@cindex Plain @TeX{}

Inside a region delineated by @code{@@iftex} and @code{@@end iftex},
you can embed some raw @TeX{} commands.  The Texinfo processors will
ignore such a region unless @TeX{} output is being produced.  You can
write the @TeX{} commands as you would write them in a normal @TeX{}
file, except that you must replace the @samp{\} used by @TeX{} with an
@samp{@@}.  For example, in the @code{@@titlepage} section of a
Texinfo file, you can use the @TeX{} command @code{@@vskip} to format
the copyright page.  (The @code{@@titlepage} command causes Info to
ignore the region automatically, as it does with the @code{@@iftex}
command.)

However, most features of plain @TeX{} will not work within
@code{@@iftex}, as they are overridden by Texinfo features.  The
purpose of @code{@@iftex} is to provide conditional processing for the
Texinfo source, not provide access to underlying formatting features.

@findex tex
You can enter plain @TeX{} completely, and use @samp{\} in the @TeX{}
commands, by delineating a region with the @code{@@tex} and @code{@@end
tex} commands.  All plain @TeX{} commands and category codes are
restored within an @code{@@tex} region.  The sole exception is that the
@code{@@} character still introduces a command, so that @code{@@end tex}
can be recognized properly.  As with @code{@@iftex}, Texinfo
processors will ignore such a region unless @TeX{} output is being produced.

@findex \gdef @r{within @code{@@tex}}
In complex cases, you may wish to define new @TeX{} macros within
@code{@@tex}.  You must use @code{\gdef} to do this, not @code{\def},
because @code{@@tex} regions are processed in a @TeX{} group.

@cindex Mathematical expressions
As an example, here is a mathematical expression written in plain @TeX{}:

@example
@@tex
$$ \chi^2 = \sum_@{i=1@}^N
         \left (y_i - (a + b x_i)
         \over \sigma_i\right)^2 $$
@@end tex
@end example

@noindent
The output of this example will appear only in a printed manual.  If
you are reading this in Info, you will not see the equation that appears
in the printed manual.
@iftex
In a printed manual, the above expression looks like
this:
@end iftex

@tex
$$ \chi^2 = \sum_{i=1}^N
         \left(y_i - (a + b x_i)
         \over \sigma_i\right)^2 $$
@end tex

@findex ifhtml
@findex html
Analogously, you can use @code{@@ifhtml @dots{} @@end ifhtml} to delimit
a region to be included in HTML output only, and @code{@@html @dots{}
@@end html} for a region of raw HTML.

@findex ifxml
@findex xml
Likewise, you can use @code{@@ifxml @dots{} @@end ifxml} to delimit
a region to be included in XML output only, and @code{@@xml @dots{}
@@end xml} for a region of raw XML.

@findex ifdocbook
@findex docbook
Again likewise, you can use @code{@@ifdocbook @dots{} @@end ifdocbook}
to delimit a region to be included in Docbook output only, and
@code{@@docbook @dots{} @@end docbook} for a region of raw Docbook.

In all cases, the exception to the raw processing is that @code{@@} is
still an escape character, so the @code{@@end} command can be
recognized.


@node set clear value
@section @code{@@set}, @code{@@clear}, and @code{@@value}

You can direct the Texinfo formatting commands to format or ignore parts
of a Texinfo file with the @code{@@set}, @code{@@clear}, @code{@@ifset},
and @code{@@ifclear} commands.

Here are brief descriptions of these commands, see the following
sections for more details:

@table @code
@item @@set @var{flag} [@var{value}]
Set the variable @var{flag}, to the optional @var{value} if specified.

@item @@clear @var{flag}
Undefine the variable @var{flag}, whether or not it was previously defined.

@item @@ifset @var{flag}
If @var{flag} is set, text through the next @code{@@end ifset} command
is formatted.  If @var{flag} is clear, text through the following
@code{@@end ifset} command is ignored.

@item @@ifclear @var{flag}
If @var{flag} is set, text through the next @code{@@end ifclear} command
is ignored.  If @var{flag} is clear, text through the following
@code{@@end ifclear} command is formatted.
@end table

@menu
* set value::                   Expand a flag variable to a string.
* ifset ifclear::               Format a region if a flag is set.
* value Example::               An easy way to update edition information.
@end menu


@node set value
@subsection @code{@@set} and @code{@@value}
@findex set
@findex value
@findex clear

You use the @code{@@set} command to specify a value for a flag, which
is later expanded by the @code{@@value} command.

A @dfn{flag} (aka @dfn{variable}) is an identifier.  It is best to use
only letters and numerals in a flag name, not @samp{-} or
@samp{_}---they will work in some contexts, but not all, due to
limitations in @TeX{}.

The value is the remainder of the input line, and can contain anything.

Write the @code{@@set} command like this:

@example
@@set foo This is a string.
@end example

@noindent
This sets the value of the flag @code{foo} to ``This is a string.''.

The Texinfo formatters then replace an @code{@@value@{@var{flag}@}}
command with the string to which @var{flag} is set.  Thus, when
@code{foo} is set as shown above, the Texinfo formatters convert this:

@example
@group
@@value@{foo@}
@exdent @r{to this:}
This is a string.
@end group
@end example

You can write an @code{@@value} command within a paragraph; but you
must write an @code{@@set} command on a line of its own.

If you write the @code{@@set} command like this:

@example
@@set foo
@end example

@noindent
without specifying a string, the value of @code{foo} is the empty string.

If you clear a previously set flag with @code{@@clear @var{flag}}, a
subsequent @code{@@value@{flag@}} command will report an error.

For example, if you set @code{foo} as follows:

@example
@@set howmuch very, very, very
@end example

@noindent
then the formatters transform

@example
@group
It is a @@value@{howmuch@} wet day.
@exdent @r{into}
It is a very, very, very wet day.
@end group
@end example

If you write

@example
@@clear howmuch
@end example

@noindent
then the formatters transform

@example
@group
It is a @@value@{howmuch@} wet day.
@exdent @r{into}
It is a @{No value for "howmuch"@} wet day.
@end group
@end example


@node ifset ifclear
@subsection @code{@@ifset} and @code{@@ifclear}

@findex ifset
When a @var{flag} is set, the Texinfo formatting commands format text
between subsequent pairs of @code{@@ifset @var{flag}} and @code{@@end
ifset} commands.  When the @var{flag} is cleared, the Texinfo formatting
commands do @emph{not} format the text.  @code{@@ifclear} operates
analogously.

Write the conditionally formatted text between @code{@@ifset @var{flag}}
and @code{@@end ifset} commands, like this:

@example
@group
@@ifset @var{flag}
@var{conditional-text}
@@end ifset
@end group
@end example

For example, you can create one document that has two variants, such as
a manual for a `large' and `small' model:

@cindex Shrubbery
@example
You can use this machine to dig up shrubs
without hurting them.

@@set large

@@ifset large
It can also dig up fully grown trees.
@@end ifset

Remember to replant promptly @dots{}
@end example

@noindent
In the example, the formatting commands will format the text between
@code{@@ifset large} and @code{@@end ifset} because the @code{large}
flag is set.

When @var{flag} is cleared, the Texinfo formatting commands do
@emph{not} format the text between @code{@@ifset @var{flag}} and
@code{@@end ifset}; that text is ignored and does not appear in either
printed or Info output.

For example, if you clear the flag of the preceding example by writing
an @code{@@clear large} command after the @code{@@set large} command
(but before the conditional text), then the Texinfo formatting commands
ignore the text between the @code{@@ifset large} and @code{@@end ifset}
commands.  In the formatted output, that text does not appear; in both
printed and Info output, you see only the lines that say, ``You can use
this machine to dig up shrubs without hurting them.  Remember to replant
promptly @dots{}''.

@findex ifclear
If a flag is cleared with an @code{@@clear @var{flag}} command, then
the formatting commands format text between subsequent pairs of
@code{@@ifclear} and @code{@@end ifclear} commands.  But if the flag
is set with @code{@@set @var{flag}}, then the formatting commands do
@emph{not} format text between an @code{@@ifclear} and an @code{@@end
ifclear} command; rather, they ignore that text.  An @code{@@ifclear}
command looks like this:

@example
@@ifclear @var{flag}
@end example


@node value Example
@subsection @code{@@value} Example

You can use the @code{@@value} command to minimize the number of
places you need to change when you record an update to a manual.
@xref{GNU Sample Texts}, for the full text of an example of using this
to work with Automake distributions.

This example is adapted from @ref{Top,, Overview, make, The GNU Make
Manual}.

@enumerate
@item
Set the flags:

@example
@group
@@set EDITION 0.35 Beta
@@set VERSION 3.63 Beta
@@set UPDATED 14 August 1992
@@set UPDATE-MONTH August 1992
@end group
@end example

@item
Write text for the @code{@@copying} section (@pxref{copying}):

@example
@group
@@copying
This is Edition @@value@{EDITION@},
last updated @@value@{UPDATED@},
of @@cite@{The GNU Make Manual@},
for @@code@{make@}, version @@value@{VERSION@}.

Copyright @dots{}

Permission is granted @dots{}
@@end copying
@end group
@end example

@item
Write text for the title page, for people reading the printed manual:

@example
@group
@@titlepage
@@title GNU Make
@@subtitle A Program for Directing Recompilation
@@subtitle Edition @@value@{EDITION@}, @dots{}
@@subtitle @@value@{UPDATE-MONTH@}
@@page
@@insertcopying
@dots{}
@@end titlepage
@end group
@end example

@noindent
(On a printed cover, a date listing the month and the year looks less
fussy than a date listing the day as well as the month and year.)

@item
Write text for the Top node, for people reading the Info file:

@example
@group
@@ifnottex
@@node Top
@@top Make

@@insertcopying
@dots{}
@@end ifnottex
@end group
@end example

After you format the manual, the @code{@@value} constructs have been
expanded, so the output contains text like this:

@example
@group
This is Edition 0.35 Beta, last updated 14 August 1992,
of `The GNU Make Manual', for `make', Version 3.63 Beta.
@end group
@end example
@end enumerate

When you update the manual, you change only the values of the flags; you
do not need to edit the three sections.


@node Conditional Nesting
@section Conditional Nesting
@cindex Conditionals, nested
@cindex Nesting conditionals

Conditionals can be nested; however, the details are a little tricky.
The difficulty comes with failing conditionals, such as
@code{@@ifhtml} when HTML is not being produced, where the included
text is to be ignored.  However, it is not to be @emph{completely}
ignored, since it is useful to have one @code{@@ifset} inside another,
for example---that is a way to include text only if two conditions are
met.  Here's an example:

@example
@@ifset somevar
@@ifset anothervar
Both somevar and anothervar are set.
@@end ifset
@@ifclear anothervar
Somevar is set, anothervar is not.
@@end ifclear
@@end ifset
@end example

Technically, Texinfo requires that for a failing conditional, the
ignored text must be properly nested with respect to that failing
conditional.  Unfortunately, it's not always feasible to check that
@emph{all} conditionals are properly nested, because then the
processors could have to fully interpret the ignored text, which
defeats the purpose of the command.  Here's an example illustrating
these rules:

@example
@@ifset a
@@ifset b
@@ifclear ok  - ok, ignored
@@end junky   - ok, ignored
@@end ifset
@@c WRONG - missing @@end ifset.
@end example

Finally, as mentioned above, all conditional commands must be on lines
by themselves, with no text (even spaces) before or after.  Otherwise,
the processors cannot reliably determine which commands to consider
for nesting purposes.


@node Internationalization
@chapter Internationalization

@cindex Internationalization
Texinfo has some support for writing in languages other than English,
although this area still needs considerable work.

For a list of the various accented and special characters Texinfo
supports, see @ref{Inserting Accents}.

@menu
* documentlanguage::            Declaring the current language.
* documentencoding::            Declaring the input encoding.
@end menu


@node documentlanguage
@section @code{@@documentlanguage @var{ll}[_@var{cc}]}: Set the Document Language

@findex documentlanguage
@cindex Language, declaring
@cindex Locale, declaring
@cindex Document language, declaring

The @code{@@documentlanguage} command declares the current document
locale.  Write it on a line by itself, near the beginning of the
file, but after @code{@@setfilename}
(@pxref{setfilename,,@code{@@setfilename}}):

@example
@@documentlanguage @var{ll}[_@var{cc}]
@end example

Include a two-letter ISO@tie{}639-2 language code (@var{ll}) following
the command name, optionally followed by an underscore and two-letter
ISO@tie{}3166 two-letter country code (@var{cc}).  If you have a
multilingual document, the intent is to be able to use this command
multiple times, to declare each language change.  If the command is
not used at all, the default is @code{en_US} for US English.

As with GNU Gettext (@pxref{Top,,,gettext, Gettext}), if the country
code is omitted, the main dialect is assumed where possible.  For
example, @code{de} is equivalent to @code{de_DE} (German as spoken in
Germany).

@cindex Document strings, translation of
For Info and other online output, this command changes the translation
of various @dfn{document strings} such as ``see'' in cross-references
(@pxref{Cross References}), ``Function' in defuns (@pxref{Definition
Commands}), and so on.  Some strings, such as ``Node:'', ``Next:'',
``Menu:'', etc., are keywords in Info output, so are not translated
there; they are translated in other output formats.

@cindex @file{txi-@var{cc}.tex}
For @TeX{}, this command causes a file @file{txi-@var{locale}.tex} to
be read (if it exists).  If @code{@@setdocumentlanguage} argument
contains the optional @samp{_@var{cc}} suffix, this is tried first.
For example, with @code{@@setdocumentlanguage de_DE}, @TeX{} first
looks for @file{txi-de_DE.tex}, then @file{txi-de.tex}.

Such a @file{txi-*} file is intended to redefine the various English
words used in @TeX{} output, such as `Chapter', `See', and so on.  We
are aware that individual words like these cannot always be translated
in isolation, and that a very different strategy would be required for
ideographic (among other) scripts.  Help in improving Texinfo's
language support is welcome.

@cindex Hyphenation patterns, language-dependent
It would also be desirable for this command to also change @TeX{}'s
ideas of the current hyphenation patterns (via the @TeX{} primitive
@code{\language}), but this is unfortunately not currently
implemented.

In September 2006, the W3C Internationalization Activity released a
new recommendation for specifying languages:
@url{http://www.rfc-editor.org/rfc/bcp/bcp47.txt}.  When Gettext
supports this new scheme, Texinfo will too.

@cindex ISO 639-2 language codes
@cindex ISO 3166 country codes
@cindex Language codes
@cindex Country codes
Since the lists of language codes and country codes are updated
relatively frequently, we don't attempt to list them here.  The valid
language codes are on the official home page for ISO@tie{}639,
@url{http://www.loc.gov/standards/iso639-2/}.  The country codes and
the official web site for ISO@tie{}3166 can be found via
@url{http://en.wikipedia.org/wiki/ISO_3166}.


@node documentencoding
@section @code{@@documentencoding @var{enc}}: Set Input Encoding

@findex documentencoding
@cindex Encoding, declaring
@cindex Input encoding, declaring
@cindex Character set, declaring
@cindex Document input encoding

The @code{@@documentencoding} command declares the input document
encoding.  Write it on a line by itself, with a valid encoding
specification following, near the beginning of the file but after
@code{@@setfilename} (@pxref{setfilename,,@code{@@setfilename}}):

@example
@@documentencoding @var{enc}
@end example

At present, Texinfo supports only these encodings:

@table @code
@item US-ASCII
This has no particular effect, but it's included for completeness.

@itemx UTF-8
The vast global character encoding, expressed in 8-bit bytes.
The Texinfo processors have no deep knowledge of Unicode; for the most
part, they just pass along the input they are given to the output.

@itemx ISO-8859-1
@itemx ISO-8859-15
@item ISO-8859-2
These specify the standard encodings for Western European (the first
two) and Eastern European languages (the third), respectively.  ISO
8859-15 replaces some little-used characters from 8859-1 (e.g.,
precomposed fractions) with more commonly needed ones, such as the
Euro symbol (@euro{}).

A full description of the encodings is beyond our scope here;
one useful reference is @uref{http://czyborra.com/charsets/iso8859.html}.

@item koi8-r
This is the commonly used encoding for the Russian language.

@item koi8-u
This is the commonly used encoding for the Ukrainian language.

@end table

Specifying an encoding @var{enc} has the following effects:

@opindex --enable-encoding
@cindex Local Variables: section, for encoding
@cindex Info output, and encoding
In Info output, unless the option @option{--disable-encoding} is given
to @command{makeinfo}, a so-called `Local Variables' section
(@pxref{File Variables,,,emacs,The GNU Emacs Manual}) is output
including @var{enc}.  This allows Info readers to set the encoding
appropriately.

@example
Local Variables:
coding: @var{enc}
End:
@end example

Also, in Info and plain text output (barring
@option{--disable-encoding}), accent constructs and special
characters, such as @code{@@'e}, are output as the actual 8-bit
character in the given encoding.

@cindex HTML output, and encodings
@cindex @code{http-equiv}, and charset specification
@cindex @code{<meta>} HTML tag, and charset specification
In HTML output, a @samp{<meta>} tag is output, in the @samp{<head>}
section of the HTML, that specifies @var{enc}.  Web servers and
browsers cooperate to use this information so the correct encoding is
used to display the page, if supported by the system.

@example
<meta http-equiv="Content-Type" content="text/html;
     charset=@var{enc}">
@end example

In split HTML output, if @option{--transliterate-file-names} is
given (@pxref{HTML Xref 8-bit Character Expansion}), the names of HTML
files are formed by transliteration of the corresponding node names,
using the specified encoding. 

In XML and Docbook output, the given document encoding is written in
the output file as usual with those formats.

In @TeX{} output, the characters which are supported in the standard
Computer Modern fonts are output accordingly.  (For example, this
means using constructed accents rather than precomposed glyphs.)
Using a missing character generates a warning message, as does
specifying an unimplemented encoding.


@node Defining New Texinfo Commands
@chapter Defining New Texinfo Commands
@cindex Macros
@cindex Defining new Texinfo commands
@cindex New Texinfo commands, defining
@cindex Texinfo commands, defining new
@cindex User-defined Texinfo commands

Texinfo provides several ways to define new commands:

@itemize @bullet
@item
A Texinfo @dfn{macro} allows you to define a new Texinfo command as any
sequence of text and/or existing commands (including other macros).  The
macro can have any number of @dfn{parameters}---text you supply each
time you use the macro.

Incidentally, these macros have nothing to do with the @code{@@defmac}
command, which is for documenting macros in the subject of the manual
(@pxref{Def Cmd Template}).

@item
@samp{@@alias} is a convenient way to define a new name for an existing
command.

@item
@samp{@@definfoenclose} allows you to define new commands with
customized output in the Info file.

@end itemize

@menu
* Defining Macros::             Defining and undefining new commands.
* Invoking Macros::             Using a macro, once you've defined it.
* Macro Details::               Limitations of Texinfo macros.
* alias::                       Command aliases.
* definfoenclose::              Customized highlighting.
@end menu


@node Defining Macros
@section Defining Macros
@cindex Defining macros
@cindex Macro definitions

@findex macro
You use the Texinfo @code{@@macro} command to define a macro, like this:

@example
@@macro @var{macroname}@{@var{param1}, @var{param2}, @dots{}@}
@var{text} @dots{} \@var{param1}\ @dots{}
@@end macro
@end example

The @dfn{parameters} @var{param1}, @var{param2}, @dots{} correspond to
arguments supplied when the macro is subsequently used in the document
(described in the next section).

@cindex Macro names, valid characters in
@cindex Names of macros, valid characters of
For a macro to work consistently with @TeX{}, @var{macroname} must
consist entirely of letters: no digits, hyphens, underscores, or other
special characters.  So, we recommend using only letters.  However,
@command{makeinfo} will accept anything except @samp{@{@}_^=};
@samp{_} and @samp{^} are excluded so that macros can be called in
@code{@@math} mode without a following space
(@pxref{math,,@code{@@math}}).

If a macro needs no parameters, you can define it either with an empty
list (@samp{@@macro foo @{@}}) or with no braces at all (@samp{@@macro
foo}).

@cindex Body of a macro
@cindex Mutually recursive macros
@cindex Recursion, mutual
The definition or @dfn{body} of the macro can contain most Texinfo
commands, including previously-defined macros.  Not-yet-defined macro
invocations are not allowed; thus, it is not possible to have mutually
recursive Texinfo macros.  Also, a macro definition that defines another
macro does not work in @TeX{} due to limitations in the design of
@code{@@macro}.

@cindex Parameters to macros
In the macro body, instances of a parameter name surrounded by
backslashes, as in @samp{\@var{param1}\} in the example above, are
replaced by the corresponding argument from the macro invocation.  You
can use parameter names any number of times in the body, including zero.

@cindex Backslash in macros
To get a single @samp{\} in the macro expansion, use @samp{\\}.  Any
other use of @samp{\} in the body yields a warning.

@cindex Spaces in macros
@cindex Whitespace in macros
The newlines after the @code{@@macro} line and before the @code{@@end
macro} line are ignored, that is, not included in the macro body.  All
other whitespace is treated according to the usual Texinfo rules.

@cindex Recursive macro invocations
@findex rmacro
To allow a macro to be used recursively, that is, in an argument to a
call to itself, you must define it with @samp{@@rmacro}, like this:

@example
@@rmacro rmac @{arg@}
a\arg\b
@@end rmacro
@dots{}
@@rmac@{1@@rmac@{text@}2@}
@end example

This produces the output `a1atextb2b'.  With @samp{@@macro} instead of
@samp{@@rmacro}, an error message is given.

@findex unmacro
@cindex Macros, undefining
@cindex Undefining macros
You can undefine a macro @var{foo} with @code{@@unmacro @var{foo}}.
It is not an error to undefine a macro that is already undefined.
For example:

@example
@@unmacro foo
@end example


@node Invoking Macros
@section Invoking Macros
@cindex Invoking macros
@cindex Expanding macros
@cindex Running macros
@cindex Macro invocation

After a macro is defined (see the previous section), you can use
(@dfn{invoke}) it in your document like this:

@example
@@@var{macroname} @{@var{arg1}, @var{arg2}, @dots{}@}
@end example

@noindent and the result will be just as if you typed the body of
@var{macroname} at that spot.  For example:

@example
@@macro foo @{p, q@}
Together: \p\ & \q\.
@@end macro
@@foo@{a, b@}
@end example

@noindent produces:

@display
Together: a & b.
@end display

@cindex Backslash, and macros
Thus, the arguments and parameters are separated by commas and delimited
by braces; any whitespace after (but not before) a comma is ignored.
The braces are required in the invocation (but not the definition), even
when the macro takes no arguments, consistent with all other Texinfo
commands.  For example:

@example
@@macro argless @{@}
No arguments here.
@@end macro
@@argless@{@}
@end example

@noindent produces:

@display
No arguments here.
@end display

@cindex Comma, in macro arguments
Passing strings containing commas as macro arguments requires special
care, since they should be properly @dfn{quoted} to prevent
@command{makeinfo} from confusing them with argument separators.  To
manually quote a comma, prepend it with a backslash character, like
this: @code{\,}.  Alternatively, use the @code{@@comma} command
(@pxref{Inserting a Comma}).  However, to facilitate use of macros,
@command{makeinfo} implements a set of rules called @dfn{automatic
quoting}:

@enumerate 1
@item If a macro takes only one argument, all commas in its invocation
are quoted by default.  For example:

@example
@group
@@macro FIXME@{text@}
@@strong@{FIXME: \text\@}
@@end macro

@@FIXME@{A nice feature, though it can be dangerous.@}
@end group
@end example

@noindent
will produce the following output

@example
@strong{FIXME: A nice feature, though it can be dangerous.}
@end example

And indeed, it can.  Namely, @command{makeinfo}
does not control number of arguments passed to one-argument
macros, so be careful when you invoke them.

@item If a macro invocation includes another command (including a
recursive invocation of itself), any commas in the nested command
invocation(s) are quoted by default.  For example, in

@example
@@say@{@@strong@{Yes, I do@}, person one@}
@end example

the comma after @samp{Yes} is implicitly quoted.  Here's another
example, with a recursive macro:

@example
@group
@@rmacro cat@{a,b@}
\a\\b\
@@end rmacro

@@cat@{@@cat@{foo, bar@}, baz@}
@end group
@end example

@noindent
will produce the string @samp{foobarbaz}.

@item Otherwise, a comma should be explicitly quoted, as above, to be
treated as a part of an argument.
@end enumerate

@cindex Braces, in macro arguments
Other characters that need to be quoted in macro arguments are
curly braces and backslash.  For example

@example
@@@var{macname} @{\\\@{\@}\,@}
@end example

@noindent
will pass the (almost certainly error-producing) argument
@samp{\@{@},} to @var{macname}.  However, commas in parameters, even
if escaped by a backslash, might cause trouble in @TeX{}.

If the macro is defined to take a single argument, and is invoked
without any braces, the entire rest of the line after the macro name is
supplied as the argument.  For example:

@example
@@macro bar @{p@}
Twice: \p\ & \p\.
@@end macro
@@bar aah
@end example

@noindent produces:

@c Sorry for cheating, but let's not require macros to process the manual.
@display
Twice: aah & aah.
@end display

If the macro is defined to take a single argument, and is invoked with
braces, the braced text is passed as the argument, regardless of
commas.  For example:

@example
@@macro bar @{p@}
Twice: \p\ & \p\.
@@end macro
@@bar@{a,b@}
@end example

@noindent produces:

@display
Twice: a,b & a,b.
@end display


@node Macro Details
@section Macro Details and Caveats
@cindex Macro details
@cindex Details of macro usage
@cindex Caveats for macro usage

Due to unavoidable limitations, certain macro-related constructs cause
problems with @TeX{}.  If you get macro-related errors when producing
the printed version of a manual, try expanding the macros with
@command{makeinfo} by invoking @command{texi2dvi} with the @samp{-E}
option (@pxref{Format with texi2dvi}).

@itemize @bullet
@item
As mentioned earlier, macro names must consist entirely of letters.

@item
It is not advisable to redefine any @TeX{} primitive, plain, or
Texinfo command name as a macro. Unfortunately this is a very large
set of names, and the possible resulting errors are unpredictable.

@item
All macros are expanded inside at least one @TeX{} group.  This means
that @code{@@set} and other such commands have no effect inside a
macro.

@item
Commas in macro arguments, even if escaped by a backslash, don't
always work.

@item
Macro arguments cannot cross lines.

@item
It is (usually) best to avoid comments inside macro definitions, but
see the next item.

@item
Macros containing a command which must be on a line by itself, such as
a conditional, cannot be invoked in the middle of a line.  In general,
the interaction of newlines in the macro definitions and invocations
depends on the precise commands and context.  You may be able to work
around some problems with judicious use of @code{@@c}.  Suppose you
define a macro that is always intended to be used on a line by itself:

@example
@@macro linemac
@@cindex whatever
@@c
@@end macro
...
foo
@@linemac
bar
@end example

Without the @code{@@c}, there will be an unwanted blank line between
the @samp{@@cindex whatever} and the @samp{bar} (one newline comes
from the macro definition, one from after the invocation), causing a
paragraph break.

On the other hand, you wouldn't want the @code{@@c} if the macro was
sometimes invoked in the middle of a line (the text after the
invocation would be treated as a comment).

@item
In general, you can't arbitrarily substitute a macro call for Texinfo
command arguments, even when the text is the same.  It might work with
some commands, it fails with others.  Best not to do it at all.  For
instance, this fails:

@example
@@macro offmacro
off
@@end macro
@@headings @@offmacro
@end example

@noindent
You would expect this to be equivalent to @code{@@headings off}, but
for @TeX{}nical reasons, it fails with a mysterious error message
(@code{Paragraph ended before @@headings was complete}).

@item
Macros cannot define macros in the natural way.  To do this, you must
use conditionals and raw @TeX{}.  For example:

@example
@@ifnottex
@@macro ctor @{name, arg@}
@@macro \name\
something involving \arg\ somehow
@@end macro
@@end macro
@@end ifnottex
@@tex
\gdef\ctor#1@{\ctorx#1,@}
\gdef\ctorx#1,#2,@{\def#1@{something involving #2 somehow@}@}
@@end tex
@end example

@end itemize

The @command{makeinfo} implementation also has limitations:

@itemize
@item
@code{@@verbatim} and macros do not mix; for instance, you can't start
a verbatim block inside a macro and end it outside.
(@xref{verbatim}.)  Starting any environment inside a macro and ending
it outside may or may not work, for that matter.

@item
Macros that completely define macros are ok, but it's not possible to
have incorrectly nested macro definitions.  That is, @code{@@macro}
and @code{@@end macro} (likewise for @code{@@rmacro}) must be
correctly paired.  For example, you cannot start a macro definition
within a macro, and then end the nested definition outside the macro.

@item
@code{@@rmacro} is a kludge.

@end itemize

One more limitation is common to both implementations: white space is
ignored at the beginnings of lines.

Future major revisions of Texinfo may ease some of these limitations
(by introducing a new macro syntax).


@node alias
@section @samp{@@alias @var{new}=@var{existing}}
@cindex Aliases, command
@cindex Command aliases
@findex alias

The @samp{@@alias} command defines a new command to be just like an
existing one.  This is useful for defining additional markup names, thus
preserving semantic information in the input even though the output
result may be the same.

Write the @samp{@@alias} command on a line by itself, followed by the
new command name, an equals sign, and the existing command name.
Whitespace around the equals sign is ignored.  Thus:
@example
@@alias @var{new} = @var{existing}
@end example

For example, if your document contains citations for both books and
some other media (movies, for example), you might like to define a
macro @code{@@moviecite@{@}} that does the same thing as an ordinary
@code{@@cite@{@}} but conveys the extra semantic information as well.
You'd do this as follows:

@example
@@alias moviecite = cite
@end example

Macros do not always have the same effect as aliases, due to vagaries
of argument parsing.  Also, aliases are much simpler to define than
macros.  So the command is not redundant.  (It was also heavily used
in the Jargon File!)

Aliases must not be recursive, directly or indirectly.

It is not advisable to redefine any @TeX{} primitive, plain, or
Texinfo command name as an alias.  Unfortunately this is a very large
set of names, and the possible resulting errors are completely random.


@node definfoenclose
@section @samp{definfoenclose}: Customized Highlighting
@cindex Highlighting, customized
@cindex Customized highlighting
@findex definfoenclose

A @code{@@definfoenclose} command may be used to define a highlighting
command for Info, but not for @TeX{}.  A command defined using
@code{@@definfoenclose} marks text by enclosing it in strings that
precede and follow the text.  You can use this to get closer control of
your Info output.

Presumably, if you define a command with @code{@@definfoenclose} for Info,
you will create a corresponding command for @TeX{}, either in
@file{texinfo.tex}, @file{texinfo.cnf}, or within an @samp{@@iftex} in
your document.

Write a @code{@@definfoenclose} command on a line and follow it with
three arguments separated by commas.  The first argument to
@code{@@definfoenclose} is the @@-command name (without the @code{@@});
the second argument is the Info start delimiter string; and the third
argument is the Info end delimiter string.  The latter two arguments
enclose the highlighted text in the Info file.  A delimiter string may
contain spaces.  Neither the start nor end delimiter is required.  If
you do not want a start delimiter but do want an end delimiter, you must
follow the command name with two commas in a row; otherwise, the Info
formatting commands will naturally misinterpret the end delimiter string
you intended as the start delimiter string.

If you do a @code{@@definfoenclose} on the name of a predefined macro
(such as @code{@@emph}, @code{@@strong}, @code{@@t}, or @code{@@i}), the
enclosure definition will override the built-in definition.

An enclosure command defined this way takes one argument in braces; this
is intended for new markup commands (@pxref{Marking Text}).

@findex phoo
For example, you can write:

@example
@@definfoenclose phoo,//,\\
@end example

@noindent
near the beginning of a Texinfo file to define @code{@@phoo} as an Info
formatting command that inserts `//' before and `\\' after the argument
to @code{@@phoo}.  You can then write @code{@@phoo@{bar@}} wherever you
want `//bar\\' highlighted in Info.

Also, for @TeX{} formatting, you could write

@example
@@iftex
@@global@@let@@phoo=@@i
@@end iftex
@end example

@noindent
to define @code{@@phoo} as a command that causes @TeX{} to typeset the
argument to @code{@@phoo} in italics.

Each definition applies to its own formatter: one for @TeX{}, the other
for @code{texinfo-format-buffer} or @code{texinfo-format-region}.  The
@code{@@definfoenclose} command need not be within @samp{@@ifinfo}, but
the raw @TeX{} commands do need to be in @samp{@@iftex}.

@findex headword
Here is another example: write

@example
@@definfoenclose headword, , :
@end example

@noindent
near the beginning of the file, to define @code{@@headword} as an Info
formatting command that inserts nothing before and a colon after the
argument to @code{@@headword}.

@samp{@@definfoenclose} definitions must not be recursive, directly or
indirectly.


@node Hardcopy
@chapter Formatting and Printing Hardcopy
@cindex Format and print hardcopy
@cindex Printing hardcopy
@cindex Hardcopy, printing it
@cindex Making a printed manual
@cindex Sorting indices
@cindex Indices, sorting
@cindex @TeX{} index sorting
@pindex texindex

There are three major shell commands for making a printed manual from a
Texinfo file: one for converting the Texinfo file into a file that will be
printed, a second for sorting indices, and a third for printing the
formatted document.  When you use the shell commands, you can either
work directly in the operating system shell or work within a shell
inside GNU Emacs.

If you are using GNU Emacs, you can use commands provided by Texinfo
mode instead of shell commands.  In addition to the three commands to
format a file, sort the indices, and print the result, Texinfo mode
offers key bindings for commands to recenter the output buffer, show the
print queue, and delete a job from the print queue.

@menu
* Use TeX::                     Use @TeX{} to format for hardcopy.
* Format with tex/texindex::    How to format with explicit shell commands.
* Format with texi2dvi::        A simpler way to format.
* Print with lpr::              How to print.
* Within Emacs::                How to format and print from an Emacs shell.
* Texinfo Mode Printing::       How to format and print in Texinfo mode.
* Compile-Command::             How to print using Emacs's compile command.
* Requirements Summary::        @TeX{} formatting requirements summary.
* Preparing for TeX::           What to do before you use @TeX{}.
* Overfull hboxes::             What are and what to do with overfull hboxes.
* smallbook::                   How to print small format books and manuals.
* A4 Paper::                    How to print on A4 or A5 paper.
* pagesizes::                   How to print with customized page sizes.
* Cropmarks and Magnification:: How to print marks to indicate the size
                                 of pages and how to print scaled up output.
* PDF Output::                  Portable Document Format output.
* Obtaining TeX::               How to Obtain @TeX{}.
@end menu

@node Use TeX
@section Use @TeX{}

The typesetting program called @TeX{} is used for formatting a Texinfo
file.  @TeX{} is a very powerful typesetting program and, if used correctly,
does an exceptionally good job.  (@xref{Obtaining TeX, , How to Obtain
@TeX{}}, for information on how to obtain @TeX{}.)

The standalone @code{makeinfo} program and Emacs functions
@code{texinfo-format-region} and @code{texinfo-format-buffer} commands
read the very same @@-commands in the Texinfo file as does @TeX{}, but
process them differently to make an Info file (@pxref{Creating an Info
File}).


@node Format with tex/texindex
@section Format with @code{tex} and @code{texindex}
@cindex Shell formatting with @code{tex} and @code{texindex}
@cindex Formatting with @code{tex} and @code{texindex}
@cindex DVI file

You can format the Texinfo file with the shell command @code{tex}
followed by the name of the Texinfo file.  For example:

@example
tex foo.texi
@end example

@noindent @TeX{} will produce a @dfn{DVI file} as well as several auxiliary
files containing information for indices, cross references, etc.  The
DVI file (for @dfn{DeVice Independent} file) can be printed on virtually
any device (see the following sections).

@pindex texindex
The @code{tex} formatting command itself does not sort the indices; it
writes an output file of unsorted index data.  To generate a printed
index after running the @command{tex} command, you first need a sorted
index to work from.  The @command{texindex} command sorts indices.
(The source file @file{texindex.c} comes as part of the standard
Texinfo distribution, among other places.)  (@command{texi2dvi} runs
@command{tex} and @command{texindex} as necessary.)

@cindex Names of index files
@cindex Index file names
The @code{tex} formatting command outputs unsorted index files under
names that obey a standard convention: the name of your main input file
with any @samp{.tex} (or similar, @pxref{tex invocation,,, web2c,
Web2c}) extension removed, followed by the two letter names of indices.
For example, the raw index output files for the input file
@file{foo.texinfo} would be @file{foo.cp}, @file{foo.vr}, @file{foo.fn},
@file{foo.tp}, @file{foo.pg} and @file{foo.ky}.  Those are exactly the
arguments to give to @code{texindex}.

@need 1000
@cindex Wildcards
@cindex Globbing
Instead of specifying all the unsorted index file names explicitly, you
can use @samp{??} as shell wildcards and give the command in this
form:

@example
texindex foo.??
@end example

@noindent
This command will run @code{texindex} on all the unsorted index files,
including any that you have defined yourself using @code{@@defindex}
or @code{@@defcodeindex}.  (You may execute @samp{texindex foo.??}
even if there are similarly named files with two letter extensions
that are not index files, such as @samp{foo.el}.  The @code{texindex}
command reports but otherwise ignores such files.)

For each file specified, @code{texindex} generates a sorted index file
whose name is made by appending @samp{s} to the input file name.  The
@code{@@printindex} command looks for a file with that name
(@pxref{Printing Indices & Menus}).  @code{texindex} does not alter the
raw index output file.

After you have sorted the indices, you need to rerun @code{tex} on the
Texinfo file.  This regenerates the DVI file, this time with
up-to-date index entries.

Finally, you may need to run @code{tex} one more time, to get the page
numbers in the cross-references correct.

To summarize, this is a five step process:

@enumerate
@item
Run @code{tex} on your Texinfo file.  This generates a DVI file (with
undefined cross-references and no indices), and the raw index files
(with two letter extensions).

@item
Run @code{texindex} on the raw index files.  This creates the
corresponding sorted index files (with three letter extensions).

@item
Run @code{tex} again on your Texinfo file.  This regenerates the DVI
file, this time with indices and defined cross-references, but with page
numbers for the cross-references from last time, generally incorrect.

@item
Sort the indices again, with @code{texindex}.

@item
Run @code{tex} one last time.  This time the correct page numbers are
written for the cross-references.
@end enumerate

@pindex texi2dvi
Alternatively, it's a one-step process: run @code{texi2dvi}
(@pxref{Format with texi2dvi}).

You need not run @code{texindex} each time after you run @code{tex}.  If
you do not, on the next run, the @code{tex} formatting command will use
whatever sorted index files happen to exist from the previous use of
@code{texindex}.  This is usually ok while you are debugging.

@cindex Auxiliary files, avoiding
@findex novalidate
@cindex Pointer validation, suppressing
@cindex Chapters, formatting one at a time
Sometimes you may wish to print a document while you know it is
incomplete, or to print just one chapter of a document.  In that case,
the usual auxiliary files that @TeX{} creates and warnings @TeX{} gives
when cross-references are not satisfied are just nuisances.  You can
avoid them with the @code{@@novalidate} command, which you must give
@emph{before} the @code{@@setfilename} command
(@pxref{setfilename,,@code{@@setfilename}}).  Thus, the beginning of
your file would look approximately like this:

@example
\input texinfo
@@novalidate
@@setfilename myfile.info
@dots{}
@end example

@noindent @code{@@novalidate} also turns off validation in
@code{makeinfo}, just like its @code{--no-validate} option
(@pxref{Pointer Validation}).


@node Format with texi2dvi
@section Format with @code{texi2dvi}
@pindex texi2dvi @r{(shell script)}

The @code{texi2dvi} command automatically runs both @TeX{} and
@command{texindex} as many times as necessary to produce a DVI file
with sorted indices and all cross-references resolved.  It is
therefore simpler than manually executing the
@code{tex}---@code{texindex}---@code{tex}---@code{tex} sequence
described in the previous section.

To run @code{texi2dvi} on an input file @file{foo.texi}, do this (where
@samp{prompt$ } is your shell prompt):

@example
prompt$ @kbd{texi2dvi foo.texi}
@end example

As shown in this example, the input filenames to @code{texi2dvi} must
include any extension (@samp{.texi}, @samp{.texinfo}, etc.).  Under
MS-DOS and perhaps in other circumstances, you may need to run @samp{sh
texi2dvi foo.texi} instead of relying on the operating system to invoke
the shell on the @samp{texi2dvi} script.

@opindex --command @r{(@command{texi2dvi})}
One useful option to @code{texi2dvi} is @samp{--command=@var{cmd}}.
This inserts @var{cmd} on a line by itself after the
@code{@@setfilename} in a temporary copy of the input file before
running @TeX{}.  With this, you can specify different printing
formats, such as @code{@@smallbook} (@pxref{smallbook}),
@code{@@afourpaper} (@pxref{A4 Paper}), or @code{@@pagesizes}
(@pxref{pagesizes}), without actually changing the document source.
(You can also do this on a site-wide basis with @file{texinfo.cnf};
@pxref{Preparing for TeX,,Preparing for @TeX{}}).

@opindex --pdf @r{(@command{texi2dvi})}
With the @option{--pdf} option, @command{texi2dvi} produces PDF output
instead of DVI (@pxref{PDF Output}), by running @command{pdftex}
instead of @command{tex}.  Alternatively, the command
@command{texi2pdf} is an abbreviation for running @samp{texi2dvi
--pdf}.  The command @command{pdftexi2dvi} is also supported as a
convenience to AUC-@TeX{} users, since the latter merely prepends
@samp{pdf} to DVI producing tools to have PDF producing tools.

@cindex @LaTeX{}, processing with @command{texi2dvi}
@command{texi2dvi} can also be used to process @LaTeX{} files; simply
run @samp{texi2dvi filename.ext}.

@opindex --language @r{(@command{texi2dvi})}
Normally @command{texi2dvi} is able to guess the input file language
by its contents and file name suffix. If, however, it fails to do so
you can specify the input language using
@option{--language=@var{lang}} command line option, where @var{lang}
is either @samp{latex} or @samp{texinfo}.

@command{texi2dvi} will use @command{etex} (or @command{pdfetex}) if
they are available; these extended versions of @TeX{} are not
required, and the DVI (or PDF) output is identical, but they simplify
the @TeX{} programming in some cases, and provide additional tracing
information when debugging @file{texinfo.tex}.

@opindex --translate-file @r{(@command{texi2dvi})}
Several options are provided for handling documents, written in
character sets other than ASCII. The
@option{--translate-file=@var{file}} option instructs
@command{texi2dvi} to translate input into internal @TeX{} character
set using @dfn{translation file} @var{file} (@pxref{TCX files, TCX
files, TCX files: Character translations, web2c, Web2c: A @TeX{}
implementation}).

@opindex --recode @r{(@command{texi2dvi})}
The options @option{--recode} and @option{--recode-from=@var{enc}}
allow conversion of an input document before running @TeX{}. The
@option{--recode} option recodes the document from encoding specified
by @samp{@@documentencoding} command
(@pxref{documentencoding,,@code{documentencoding}}) to plain 7-bit
@samp{texinfo} encoding.

@opindex --recode-from @r{(@command{texi2dvi})}
The option @option{--recode-from=@var{enc}} recodes the document from
@var{enc} encoding to the encoding specified by
@samp{@@documentencoding}. This is useful, for example, if the
document is written in @samp{UTF-8} encoding and an equivalent 8-bit
encoding is supported by @command{makeinfo}.

Both @option{--recode} and @option{--recode-from=@var{enc}} use
@command{recode} utility to perform the conversion. If
@command{recode} fails to process the file, @command{texi2dvi} prints
a warning and continues using unmodified input file.

For a list of other options, run @samp{texi2dvi --help}.


@node Print with lpr
@section Shell Print Using @code{lpr -d}
@pindex lpr @r{(DVI print command)}

The precise command to print a DVI file depends on your system
installation.  Two common ones are @samp{dvips foo.dvi -o} and @samp{lpr
-d foo.dvi}.

For example, the following commands will (perhaps) suffice to sort the
indices, format, and print the @cite{Bison Manual}:

@example
@group
tex bison.texinfo
texindex bison.??
tex bison.texinfo
lpr -d bison.dvi
@end group
@end example

@noindent
(Remember that the shell commands may be different at your site; but
these are commonly used versions.)

Using the @code{texi2dvi} shell script (see the previous section):

@example
@group
texi2dvi bison.texinfo
lpr -d bison.dvi
# or perhaps dvips bison.dvi -o
@end group
@end example

@cindex Shell printing, on MS-DOS/MS-Windows
@cindex Printing DVI files, on MS-DOS/MS-Windows
@pindex lpr@r{-d, replacements on MS-DOS/MS-Windows}
@code{lpr} is a standard program on Unix systems, but it is usually
absent on MS-DOS/MS-Windows.  Some network packages come with a
program named @code{lpr}, but these are usually limited to sending files
to a print server over the network, and generally don't support the
@samp{-d} option.  If you are unfortunate enough to work on one of these
systems, you have several alternative ways of printing DVI files:

@itemize @bullet{}
@item Find and install a Unix-like @code{lpr} program, or its clone.
If you can do that, you will be able to print DVI files just like
described above.

@item Send the DVI files to a network printer queue for DVI files.
Some network printers have special queues for printing DVI files.  You
should be able to set up your network software to send files to that
queue.  In some cases, the version of @code{lpr} which comes with your
network software will have a special option to send a file to specific
queues, like this:

@example
lpr -Qdvi -hprint.server.domain bison.dvi
@end example

@item Convert the DVI file to a Postscript or PCL file and send it to your
local printer.  @xref{Invoking Dvips,,, dvips, Dvips}, and the man
pages for @code{dvilj}, for detailed description of these tools.  Once
the DVI file is converted to the format your local printer understands
directly, just send it to the appropriate port, usually @samp{PRN}.
@end itemize


@node Within Emacs
@section From an Emacs Shell
@cindex Print, format from Emacs shell
@cindex Format, print from Emacs shell
@cindex Shell, format, print from
@cindex Emacs shell, format, print from
@cindex GNU Emacs shell, format, print from

You can give formatting and printing commands from a shell within GNU
Emacs.  To create a shell within Emacs, type @kbd{M-x shell}.  In this
shell, you can format and print the document.  @xref{Hardcopy, , Format
and Print Hardcopy}, for details.

You can switch to and from the shell buffer while @code{tex} is
running and do other editing.  If you are formatting a long document
on a slow machine, this can be very convenient.@refill

You can also use @code{texi2dvi} from an Emacs shell.  For example,
here is how to use @code{texi2dvi} to format and print @cite{Using and
Porting GNU CC} from a shell within Emacs:

@example
@group
texi2dvi gcc.texinfo
lpr -d gcc.dvi
@end group
@end example

See the next section for more information about formatting
and printing in Texinfo mode.


@node Texinfo Mode Printing
@section Formatting and Printing in Texinfo Mode
@cindex Region printing in Texinfo mode
@cindex Format and print in Texinfo mode
@cindex Print and format in Texinfo mode

Texinfo mode provides several predefined key commands for @TeX{}
formatting and printing.  These include commands for sorting indices,
looking at the printer queue, killing the formatting job, and
recentering the display of the buffer in which the operations
occur.@refill

@table @kbd
@item C-c C-t C-b
@itemx M-x texinfo-tex-buffer
Run @code{texi2dvi} on the current buffer.@refill

@item C-c C-t C-r
@itemx M-x texinfo-tex-region
Run @TeX{} on the current region.@refill

@item C-c C-t C-i
@itemx M-x texinfo-texindex
Sort the indices of a Texinfo file formatted with
@code{texinfo-tex-region}.@refill

@item C-c C-t C-p
@itemx M-x texinfo-tex-print
Print a DVI file that was made with @code{texinfo-tex-region} or
@code{texinfo-tex-buffer}.@refill

@item C-c C-t C-q
@itemx M-x tex-show-print-queue
Show the print queue.@refill

@item C-c C-t C-d
@itemx M-x texinfo-delete-from-print-queue
Delete a job from the print queue; you will be prompted for the job
number shown by a preceding @kbd{C-c C-t C-q} command
(@code{texinfo-show-tex-print-queue}).@refill

@item C-c C-t C-k
@itemx M-x tex-kill-job
Kill the currently running @TeX{} job started by either
@code{texinfo-tex-region} or @code{texinfo-tex-buffer}, or any other
process running in the Texinfo shell buffer.@refill

@item C-c C-t C-x
@itemx M-x texinfo-quit-job
Quit a @TeX{} formatting job that has stopped because of an error by
sending an @key{x} to it.  When you do this, @TeX{} preserves a record
of what it did in a @file{.log} file.@refill

@item C-c C-t C-l
@itemx M-x tex-recenter-output-buffer
Redisplay the shell buffer in which the @TeX{} printing and formatting
commands are run to show its most recent output.@refill
@end table

@need 1000
Thus, the usual sequence of commands for formatting a buffer is as
follows (with comments to the right):@refill

@example
@group
C-c C-t C-b             @r{Run @code{texi2dvi} on the buffer.}
C-c C-t C-p             @r{Print the DVI file.}
C-c C-t C-q             @r{Display the printer queue.}
@end group
@end example

The Texinfo mode @TeX{} formatting commands start a subshell in Emacs
called the @file{*tex-shell*}.  The @code{texinfo-tex-command},
@code{texinfo-texindex-command}, and @code{tex-dvi-print-command}
commands are all run in this shell.

You can watch the commands operate in the @samp{*tex-shell*} buffer,
and you can switch to and from and use the @samp{*tex-shell*} buffer
as you would any other shell buffer.@refill

@need 1500
The formatting and print commands depend on the values of several variables.
The default values are:@refill

@example
@group
    @r{Variable}                              @r{Default value}

texinfo-texi2dvi-command                  "texi2dvi"
texinfo-tex-command                       "tex"
texinfo-texindex-command                  "texindex"
texinfo-delete-from-print-queue-command   "lprm"
texinfo-tex-trailer                       "@@bye"
tex-start-of-header                       "%**start"
tex-end-of-header                         "%**end"
tex-dvi-print-command                     "lpr -d"
tex-show-queue-command                    "lpq"
@end group
@end example

You can change the values of these variables with the @kbd{M-x
set-variable} command (@pxref{Examining, , Examining and Setting
Variables, emacs, The GNU Emacs Manual}), or with your @file{.emacs}
initialization file (@pxref{Init File, , , emacs, The GNU Emacs
Manual}).

@cindex Customize Emacs package (@t{Development/Docs/Texinfo})
Beginning with version 20, GNU Emacs offers a user-friendly interface,
called @dfn{Customize}, for changing values of user-definable variables.
@xref{Easy Customization, , Easy Customization Interface, emacs, The GNU
Emacs Manual}, for more details about this.  The Texinfo variables can
be found in the @samp{Development/Docs/Texinfo} group, once you invoke
the @kbd{M-x customize} command.


@node Compile-Command
@section Using the Local Variables List
@cindex Local variables
@cindex Compile command for formatting
@cindex Format with the compile command

Yet another way to apply the @TeX{} formatting command to a Texinfo file
is to put that command in a @dfn{local variables list} at the end of the
Texinfo file.  You can then specify the @code{tex} or @code{texi2dvi}
commands as a @code{compile-command} and have Emacs run it by typing
@kbd{M-x compile}.  This creates a special shell called the
@file{*compilation*} buffer in which Emacs runs the compile command.
For example, at the end of the @file{gdb.texinfo} file, after the
@code{@@bye}, you could put the following:@refill

@example
@group
Local Variables:
compile-command: "texi2dvi gdb.texinfo"
End:
@end group
@end example

@noindent
This technique is most often used by programmers who also compile programs
this way; see @ref{Compilation, , , emacs, The GNU Emacs Manual}.@refill


@node Requirements Summary
@section @TeX{} Formatting Requirements Summary
@cindex Requirements for formatting
@cindex Minimal requirements for formatting
@cindex Formatting requirements

Every Texinfo file that is to be input to @TeX{} must begin with a
@code{\input} command and must contain an @code{@@setfilename} command:

@example
\input texinfo
@@setfilename @var{arg-not-used-by-@TeX{}}
@end example

@noindent
The first command instructs @TeX{} to load the macros it needs to
process a Texinfo file and the second command opens auxiliary files.

Every Texinfo file must end with a line that terminates @TeX{}'s
processing and forces out unfinished pages:

@example
@@bye
@end example

Strictly speaking, these lines are all a Texinfo file needs to be
processed successfully by @TeX{}.

Usually, however, the beginning includes an @code{@@settitle} command to
define the title of the printed manual, an @code{@@setchapternewpage}
command, a title page, a copyright page, and permissions.  Besides an
@code{@@bye}, the end of a file usually includes indices and a table of
contents.  (And of course most manuals contain a body of text as well.)

For more information, see:

@itemize @bullet
@item @ref{settitle, , @code{@@settitle}}.
@item @ref{setchapternewpage, , @code{@@setchapternewpage}}.
@item @ref{Headings, ,Page Headings}.
@item @ref{Titlepage & Copyright Page}.
@item @ref{Printing Indices & Menus}.
@item @ref{Contents}.
@end itemize


@node Preparing for TeX
@section Preparing for @TeX{}
@cindex Preparing for @TeX{}
@cindex @TeX{} input initialization
@cindex @b{.profile} initialization file
@cindex @b{.cshrc} initialization file
@cindex Initialization file for @TeX{} input

@TeX{} needs to know where to find the @file{texinfo.tex} file that the
@samp{\input texinfo} command on the first line reads.  The
@file{texinfo.tex} file tells @TeX{} how to handle @@-commands; it is
included in all standard GNU distributions.  The latest version is
always available from the Texinfo source repository:
@smalldisplay
@uref{http://savannah.gnu.org/cgi-bin/viewcvs/texinfo/texinfo/doc/texinfo.tex?rev=HEAD}
@end smalldisplay

@pindex texinfo.tex@r{, installing}

Usually, the installer has put the @file{texinfo.tex} file in the
default directory that contains @TeX{} macros when GNU Texinfo, Emacs or
other GNU software is installed.  In this case, @TeX{} will find the
file and you do not need to do anything special.  If this has not been
done, you can put @file{texinfo.tex} in the current directory when you
run @TeX{}, and @TeX{} will find it there.

@pindex epsf.tex@r{, installing}
Also, you should install @file{epsf.tex}, if it is not already installed
from another distribution.  More details are at the end of the description
of the @code{@@image} command (@pxref{Images}).

@cindex European Computer Modern fonts, installing
@cindex EC fonts, installing
@cindex CM-Super fonts, installing
To be able to use quotation marks other than those used in English
you'll need to install European Computer Modern fonts and optionally
CM-Super fonts, unless they are already installed (@pxref{Inserting
Quotation Marks}).

@pindex feymr10@r{, installing}
@cindex Euro font, installing
If you intend to use the @code{@@euro} command, you should install the
Euro font, if it is not already installed.  @xref{euro}.

@pindex texinfo.cnf @r{installation}
@cindex Customizing of @TeX{} for Texinfo
@cindex Site-wide Texinfo configuration file
Optionally, you may create an additional @file{texinfo.cnf}, and install
it as well.  This file is read by @TeX{} when the @code{@@setfilename}
command is executed (@pxref{setfilename,, @code{@@setfilename}}).  You can put any
commands you like there, according to local site-wide conventions.  They
will be read by @TeX{} when processing any Texinfo document.  For
example, if @file{texinfo.cnf} contains the line @samp{@@afourpaper}
(@pxref{A4 Paper}), then all Texinfo documents will be processed with
that page size in effect.  If you have nothing to put in
@file{texinfo.cnf}, you do not need to create it.

@cindex Environment variable @code{TEXINPUTS}
@vindex TEXINPUTS
If neither of the above locations for these system files suffice for
you, you can specify the directories explicitly.  For
@file{texinfo.tex}, you can do this by writing the complete path for the
file after the @code{\input} command.  Another way, that works for both
@file{texinfo.tex} and @file{texinfo.cnf} (and any other file @TeX{}
might read), is to set the @code{TEXINPUTS} environment variable in your
@file{.cshrc} or @file{.profile} file.

Which you use of @file{.cshrc} or @file{.profile} depends on
whether you use a Bourne shell-compatible (@code{sh}, @code{bash},
@code{ksh}, @dots{}) or C shell-compatible (@code{csh}, @code{tcsh})
command interpreter.  The latter read the @file{.cshrc} file for
initialization information, and the former read @file{.profile}.

In a @file{.cshrc} file, you could use the following @code{csh} command
sequence:

@example
setenv TEXINPUTS .:/home/me/mylib:
@end example

@need 1000
In a @file{.profile} file, you could use the following @code{sh} command
sequence:

@example
@group
TEXINPUTS=.:/home/me/mylib:
export TEXINPUTS
@end group
@end example

On MS-DOS/MS-Windows, you would say it like this@footnote{Note the use
of the @samp{;} character, instead of @samp{:}, as directory separator
on these systems.}:

@example
@group
set TEXINPUTS=.;d:/home/me/mylib;c:
@end group
@end example

@noindent
It is customary for DOS/Windows users to put such commands in the
@file{autoexec.bat} file, or in the Windows Registry.

@noindent
These settings would cause @TeX{} to look for @file{\input} file first
in the current directory, indicated by the @samp{.}, then in a
hypothetical user @samp{me}'s @file{mylib} directory, and finally in
the system directories.  (A leading, trailing, or doubled @samp{:}
indicates searching the system directories at that point.)

@cindex Dumping a .fmt file
@cindex Format file, dumping
Finally, you may wish to dump a @file{.fmt} file (@pxref{Memory dumps,,,
web2c, Web2c}) so that @TeX{} can load Texinfo faster.  (The
disadvantage is that then updating @file{texinfo.tex} requires
redumping.)  You can do this by running this command, assuming
@file{epsf.tex} is findable by @TeX{}:

@example
initex texinfo @@dump
@end example

@noindent
(@code{dump} is a @TeX{} primitive.)  Then, move @file{texinfo.fmt} to
wherever your @code{.fmt} files are found; typically, this will be in the
subdirectory @file{web2c} of your @TeX{} installation.


@node Overfull hboxes
@section Overfull ``hboxes''
@cindex Overfull @samp{hboxes}
@cindex @samp{hboxes}, overfull
@cindex Final output

@TeX{} is sometimes unable to typeset a line without extending it into
the right margin.  This can occur when @TeX{} comes upon what it
interprets as a long word that it cannot hyphenate, such as an
electronic mail network address or a very long title.  When this
happens, @TeX{} prints an error message like this:

@example
Overfull @@hbox (20.76302pt too wide)
@end example

@findex hbox
@noindent
(In @TeX{}, lines are in ``horizontal boxes'', hence the term, ``hbox''.
@samp{@@hbox} is a @TeX{} primitive not needed in the Texinfo language.)

@TeX{} also provides the line number in the Texinfo source file and
the text of the offending line, which is marked at all the places that
@TeX{} considered hyphenation.
@xref{Debugging with TeX, , Catching Errors with @TeX{} Formatting},
for more information about typesetting errors.

If the Texinfo file has an overfull hbox, you can rewrite the sentence
so the overfull hbox does not occur, or you can decide to leave it.  A
small excursion into the right margin often does not matter and may not
even be noticeable.

If you have many overfull boxes and/or an antipathy to rewriting, you
can coerce @TeX{} into greatly increasing the allowable interword
spacing, thus (if you're lucky) avoiding many of the bad line breaks,
like this:

@findex \emergencystretch
@example
@@tex
\global\emergencystretch = .9\hsize
@@end tex
@end example

@noindent
(You should adjust the fraction as needed.)  This huge value for
@code{\emergencystretch} cannot be the default, since then the typeset
output would generally be of noticeably lower quality; the default
is @samp{.15\hsize}.  @code{\hsize} is the @TeX{} dimension
containing the current line width.

@cindex Black rectangle in hardcopy
@cindex Rectangle, black in hardcopy
@cindex Box, ugly black in hardcopy
@cindex Ugly black rectangles in hardcopy
For what overfull boxes you have, however, @TeX{} will print a large,
ugly, black rectangle beside the line that contains the overfull hbox
unless told otherwise.  This is so you will notice the location of the
problem if you are correcting a draft.

@findex finalout
To prevent such a monstrosity from marring your final printout, write
the following in the beginning of the Texinfo file on a line of its own,
before the @code{@@titlepage} command:

@example
@@finalout
@end example


@node smallbook
@section Printing ``Small'' Books
@findex smallbook
@cindex Small book size
@cindex Book, printing small
@cindex Page sizes for books
@cindex Size of printed book

By default, @TeX{} typesets pages for printing in an 8.5 by 11 inch
format.  However, you can direct @TeX{} to typeset a document in a 7 by
9.25 inch format that is suitable for bound books by inserting the
following command on a line by itself at the beginning of the Texinfo
file, before the title page:@refill

@example
@@smallbook
@end example

@noindent
(Since many books are about 7 by 9.25 inches, this command might better
have been called the @code{@@regularbooksize} command, but it came to be
called the @code{@@smallbook} command by comparison to the 8.5 by 11
inch format.)

If you write the @code{@@smallbook} command between the
start-of-header and end-of-header lines, the Texinfo mode @TeX{}
region formatting command, @code{texinfo-tex-region}, will format the
region in ``small'' book size (@pxref{Start of Header}).@refill

@xref{small}, for information about
commands that make it easier to produce examples for a smaller manual.

@xref{Format with texi2dvi}, and @ref{Preparing for TeX,,Preparing for
@TeX{}}, for other ways to format with @code{@@smallbook} that do not
require changing the source file.


@node A4 Paper
@section Printing on A4 Paper
@cindex A4 paper, printing on
@cindex A5 paper, printing on
@cindex Paper size, A4
@cindex European A4 paper
@findex afourpaper

You can tell @TeX{} to format a document for printing on European size
A4 paper (or A5) with the @code{@@afourpaper} (or @code{@@afivepaper})
command.  Write the command on a line by itself near the beginning of
the Texinfo file, before the title page.  For example, this is how you
would write the header for this manual:

@example
@group
\input texinfo    @@c -*-texinfo-*-
@@c %**start of header
@@setfilename texinfo
@@settitle Texinfo
@@afourpaper
@@c %**end of header
@end group
@end example

@xref{Format with texi2dvi}, and @ref{Preparing for TeX,,Preparing for
@TeX{}}, for other ways to format for different paper sizes that do not
require changing the source file.

@findex afourlatex
@findex afourwide
You may or may not prefer the formatting that results from the command
@code{@@afourlatex}.  There's also @code{@@afourwide} for A4 paper in
wide format.

@node pagesizes
@section @code{@@pagesizes} [@var{width}][, @var{height}]: Custom Page Sizes
@findex pagesizes
@cindex Custom page sizes
@cindex Page sizes, customized
@cindex Text width and height
@cindex Width of text area
@cindex Height of text area
@cindex Depth of text area

You can explicitly specify the height and (optionally) width of the main
text area on the page with the @code{@@pagesizes} command.  Write this
on a line by itself near the beginning of the Texinfo file, before the
title page.  The height comes first, then the width if desired,
separated by a comma.  Examples:

@example
@@pagesizes 200mm,150mm  @c for b5 paper
@end example
@noindent and
@example
@@pagesizes 11.5in      @c for legal paper
@end example

@cindex B5 paper, printing on
@cindex Legal paper, printing on
This would be reasonable for printing on B5-size paper.  To emphasize,
this command specifies the size of the @emph{text area}, not the size of
the paper (which is 250@dmn{mm} by 177@dmn{mm} for B5, 14@dmn{in} by
8.5@dmn{in} for legal).

@cindex Margins on page, not controllable
To make more elaborate changes, such as changing any of the page
margins, you must define a new command in @file{texinfo.tex} (or
@file{texinfo.cnf}, @pxref{Preparing for TeX,,Preparing for @TeX{}}).

@xref{Format with texi2dvi}, and @ref{Preparing for TeX,,Preparing for
@TeX{}}, for other ways to specify @code{@@pagesizes} that do not
require changing the source file.

@code{@@pagesizes} is ignored by @code{makeinfo}.


@node Cropmarks and Magnification
@section Cropmarks and Magnification
@findex cropmarks
@cindex Cropmarks for printing
@cindex Printing cropmarks
You can (attempt to) direct @TeX{} to print cropmarks at the corners of
pages with the @code{@@cropmarks} command.  Write the @code{@@cropmarks}
command on a line by itself between @code{@@iftex} and @code{@@end
iftex} lines near the beginning of the Texinfo file, before the title
page, like this:@refill

@example
@group
@@iftex
@@cropmarks
@@end iftex
@end group
@end example

This command is mainly for printers that typeset several pages on one
sheet of film; but you can attempt to use it to mark the corners of a
book set to 7 by 9.25 inches with the @code{@@smallbook} command.
(Printers will not produce cropmarks for regular sized output that is
printed on regular sized paper.)  Since different printing machines work
in different ways, you should explore the use of this command with a
spirit of adventure.  You may have to redefine the command in
@file{texinfo.tex}.

@findex \mag @r{(raw @TeX{} magnification)}
@cindex Magnified printing
@cindex Larger or smaller pages
You can attempt to direct @TeX{} to typeset pages larger or smaller than
usual with the @code{\mag} @TeX{} command.  Everything that is typeset
is scaled proportionally larger or smaller.  (@code{\mag} stands for
``magnification''.)  This is @emph{not} a Texinfo @@-command, but is a
plain @TeX{} command that is prefixed with a backslash.  You have to
write this command between @code{@@tex} and @code{@@end tex}
(@pxref{Raw Formatter Commands}).

Follow the @code{\mag} command with an @samp{=} and then a number that
is 1000 times the magnification you desire.  For example, to print pages
at 1.2 normal size, write the following near the beginning of the
Texinfo file, before the title page:

@example
@group
@@tex
\mag=1200
@@end tex
@end group
@end example

With some printing technologies, you can print normal-sized copies that
look better than usual by giving a larger-than-normal master to your
print shop.  They do the reduction, thus effectively increasing the
resolution.

Depending on your system, DVI files prepared with a
nonstandard-@code{\mag} may not print or may print only with certain
magnifications.  Be prepared to experiment.


@node PDF Output
@section PDF Output
@cindex PDF output

@pindex pdftex
The simplest way to generate PDF output from Texinfo source is to run
the convenience script @command{texi2pdf} (or @command{pdftexi2dvi});
this simply executes the @command{texi2dvi} script with the
@option{--pdf} option (@pxref{Format with texi2dvi}).  If for some
reason you want to process the document by hand, simply run the
@command{pdftex} program instead of plain @command{tex}.  That is, run
@samp{pdftex foo.texi} instead of @samp{tex foo.texi}.

@dfn{PDF} stands for `Portable Document Format'. It was invented by
Adobe Systems some years ago for document interchange, based on their
PostScript language.  Related links:

@itemize
@item
GNU GV, a @uref{http://www.foolabs.com/xpdf/, Ghostscript-based PDF
reader}.  (It can also preview PostScript documents.)

@item
A freely available standalone @uref{http://www.foolabs.com/xpdf/,
PDF reader} for the X window system.

@item
@uref{http://partners.adobe.com/asn/acrobat/sdk/public/docs/, PDF definition}.

@end itemize

At present, Texinfo does not provide
@samp{@@ifpdf} or @samp{@@pdf} commands as for the other output
formats, since PDF documents contain many internal links that would be
hard or impossible to get right at the Texinfo source level.

PDF files require special software to be displayed, unlike the plain
ASCII formats (Info, HTML) that Texinfo supports.  They also tend to
be much larger than the DVI files output by @TeX{} by default.
Nevertheless, a PDF file does define an actual typeset document in a
self-contained file, so it has its place.


@node Obtaining TeX
@section How to Obtain @TeX{}
@cindex Obtaining @TeX{}
@cindex @TeX{}, how to obtain

@c !!! Here is information about obtaining TeX.  Update it whenever.
@c !!! Also consider updating TeX.README on ftp.gnu.org.
@c     Updated by RJC on 1 March 1995, conversation with MacKay.
@c     Updated by kb@cs.umb.edu on 29 July 1996.
@c     Updated by kb@cs.umb.edu on 25 April 1997.
@c     Updated by kb@cs.umb.edu on 27 February 1998.
@TeX{} is freely redistributable.  You can obtain @TeX{} for Unix
systems via anonymous ftp or on physical media.  The core material
consists of the Web2c @TeX{} distribution (@uref{http://tug.org/web2c}).

Instructions for retrieval by anonymous ftp and information on other
available distributions:
@uref{http://tug.org/unixtex.ftp}.

The Free Software Foundation provides a core distribution on its Source
Code CD-ROM suitable for printing Texinfo manuals.  To order it, contact:

@display
@group
Free Software Foundation, Inc.
51 Franklin St, Fifth Floor
Boston, MA @ @ 02110-1301
USA
Telephone: @w{+1-617-542-5942}
Fax: (including Japan) @w{+1-617-542-2652}
Free Dial Fax (in Japan):
@w{ } @w{ } @w{ } 0031-13-2473 (KDD)
@w{ } @w{ } @w{ } 0066-3382-0158 (IDC)
Electronic mail: @code{gnu@@gnu.org}
@end group
@end display

Many other @TeX{} distributions are available; see
@uref{http://tug.org/}.


@node Creating and Installing Info Files
@chapter Creating and Installing Info Files

This chapter describes how to create and install Info files.  @xref{Info
Files}, for general information about the file format itself.

@menu
* Creating an Info File::
* Installing an Info File::
@end menu


@node Creating an Info File
@section Creating an Info File
@cindex Creating an Info file
@cindex Info, creating an online file
@cindex Formatting a file for Info

@code{makeinfo} is a program that converts a Texinfo file into an Info
file, HTML file, or plain text.  @code{texinfo-format-region} and
@code{texinfo-format-buffer} are GNU Emacs functions that convert
Texinfo to Info.

For information on installing the Info file in the Info system,
@pxref{Installing an Info File}.

@menu
* makeinfo advantages::         @code{makeinfo} provides better error checking.
* Invoking makeinfo::           How to run @code{makeinfo} from a shell.
* makeinfo options::            Specify fill-column and other options.
* Pointer Validation::          How to check that pointers point somewhere.
* makeinfo in Emacs::           How to run @code{makeinfo} from Emacs.
* texinfo-format commands::     Two Info formatting commands written
                                 in Emacs Lisp are an alternative
                                 to @code{makeinfo}.
* Batch Formatting::            How to format for Info in Emacs Batch mode.
* Tag and Split Files::         How tagged and split files help Info
                                 to run better.
@end menu


@node makeinfo advantages
@subsection @code{makeinfo} Preferred

The @code{makeinfo} utility creates an Info file from a Texinfo source
file more quickly than either of the Emacs formatting commands and
provides better error messages.  We recommend it.  @code{makeinfo} is a
C program that is independent of Emacs.  You do not need to run Emacs to
use @code{makeinfo}, which means you can use @code{makeinfo} on machines
that are too small to run Emacs.  You can run @code{makeinfo} in any one
of three ways: from an operating system shell, from a shell inside
Emacs, or by typing the @kbd{C-c C-m C-r} or the @kbd{C-c C-m C-b}
command in Texinfo mode in Emacs.

The @code{texinfo-format-region} and the @code{texinfo-format-buffer}
commands are useful if you cannot run @code{makeinfo}.  Also, in some
circumstances, they format short regions or buffers more quickly than
@code{makeinfo}.


@node Invoking makeinfo
@subsection Running @code{makeinfo} from a Shell
@pindex makeinfo

To create an Info file from a Texinfo file, invoke @command{makeinfo}
followed by the name of the Texinfo file.  Thus, to create the Info
file for Bison, type the following to the shell:

@example
makeinfo bison.texinfo
@end example

(You can run a shell inside Emacs by typing @kbd{M-x shell}.)

@command{makeinfo} has many options to control its actions and output;
see the next section.

You can give @command{makeinfo} more than one input file name; each is
processed in turn.  If an input file name is @samp{-}, or no input
file names are given at all, standard input is read.


@node makeinfo options
@subsection Options for @code{makeinfo}
@cindex @code{makeinfo} options
@cindex Options for @code{makeinfo}

The @command{makeinfo} program accepts many options.  Perhaps the most
commonly needed are those that change the output format.  By default,
@command{makeinfo} outputs Info files.

Each command line option is a word preceded by @samp{--} or a letter
preceded by @samp{-}.  You can use abbreviations for the long option
names as long as they are unique.

For example, you could use the following shell command to create an Info
file for @file{bison.texinfo} in which each line is filled to only 68
columns:

@example
makeinfo --fill-column=68 bison.texinfo
@end example

You can write two or more options in sequence, like this:@refill

@example
makeinfo --no-split --fill-column=70 @dots{}
@end example

@noindent
This would keep the Info file together as one possibly very long
file and would also set the fill column to 70.

The options are:

@table @code

@item -D @var{var}
@opindex -D @var{var}
Cause the variable @var{var} to be defined.  This is equivalent to
@code{@@set @var{var}} in the Texinfo file (@pxref{set clear value}).

@item --commands-in-node-names
@opindex --commands-in-node-names
Allow @code{@@}-commands in node names.  This is not recommended, as it
can probably never be implemented in @TeX{}.  It also makes
@code{makeinfo} much slower.  Also, this option is ignored when
@samp{--no-validate} is used.  @xref{Pointer Validation}, for more
details.

@item --css-include=@var{file}
@opindex --css-include
Include the contents of @var{file}, which should contain cascading
style sheets specifications, in the @samp{<style>} block of the HTML
output.  @xref{HTML CSS}.  If @var{file} is @samp{-}, read standard
input.

@item --css-ref=@var{url}
@opindex --css-ref
In HTML mode, add a @samp{<link>} tag to the HTML output which
references a cascading style sheet at @var{url}. This allows using
standalone style sheets.

@item --disable-encoding
@itemx --enable-encoding
@opindex --disable-encoding
@opindex --enable-encoding
By default, or with @option{--enable-encoding}, output accented and
special characters in Info or plain text output based on
@samp{@@documentencoding}.  With @option{--disable-encoding}, 7-bit
ASCII transliterations are output.
@xref{documentencoding,,@code{documentencoding}}, and @ref{Inserting
Accents}.

@item --docbook
@opindex --docbook
Generate Docbook output rather than Info.

@item --document-language=@var{lang}
@opindex --document-language
@vindex LANG
Use @var{lang} to translate Texinfo keywords which end up in the
output document.  The default is the locale specified by the
@code{@@documentlanguage} command if there is one
(@pxref{documentlanguage}).

@item --error-limit=@var{limit}
@itemx -e @var{limit}
@opindex --error-limit=@var{limit}
@opindex -e @var{limit}
Set the maximum number of errors that @code{makeinfo} will report
before exiting (on the assumption that continuing would be useless);
default 100.

@item --fill-column=@var{width}
@itemx -f @var{width}
@opindex --fill-column=@var{width}
@opindex -f @var{width}
Specify the maximum number of columns in a line; this is the right-hand
edge of a line.  Paragraphs that are filled will be filled to this
width.  (Filling is the process of breaking up and connecting lines so
that lines are the same length as or shorter than the number specified
as the fill column.  Lines are broken between words.) The default value
is 72.  Ignored with @samp{--html}.

@item --footnote-style=@var{style}
@itemx -s @var{style}
@opindex --footnote-style=@var{style}
@opindex -s @var{style}
Set the footnote style to @var{style}, either @samp{end} for the end
node style (the default) or @samp{separate} for the separate node style.
The value set by this option overrides the value set in a Texinfo file
by an @code{@@footnotestyle} command (@pxref{Footnotes}).  When the
footnote style is @samp{separate}, @code{makeinfo} makes a new node
containing the footnotes found in the current node.  When the footnote
style is @samp{end}, @code{makeinfo} places the footnote references at
the end of the current node.  Ignored with @samp{--html}.

@item --force
@itemx -F
@opindex --force
@opindex -F
Ordinarily, if the input file has errors, the output files are not
created.  With this option, they are preserved.

@item --help
@itemx -h
@opindex --help
@opindex -h
Print a usage message listing all available options, then exit successfully.

@item --html
@opindex --html
Generate HTML output rather than Info.  @xref{Generating HTML}.  By
default, the HTML output is split into one output file per Texinfo
source node, and the split output is written into a subdirectory with
the name of the top-level info file.

@item -I @var{dir}
@opindex -I @var{dir}
Append @var{dir} to the directory search list for finding files that
are included using the @code{@@include} command.  By default,
@code{makeinfo} searches only the current directory.  If @var{dir} is
not given, the current directory @file{.} is appended.  Note that
@var{dir} can actually be a list of several directories separated by the
usual path separator character (@samp{:} on Unix, @samp{;} on
MS-DOS/MS-Windows).

@item --ifdocbook
@opindex --ifdocbook
@itemx --ifhtml
@opindex --ifhtml
@itemx --ifinfo
@opindex --ifinfo
@itemx --ifplaintext
@opindex --ifplaintext
@itemx --iftex
@opindex --iftex
@itemx --ifxml
@opindex --ifxml
For the specified format, process @samp{@@if@var{format}} and
@samp{@@@var{format}} commands even if not generating the given output
format.  For instance, if @option{--iftex} is specified, then
@samp{@@iftex} and @samp{@@tex} blocks will be read.  

@item --internal-links=@var{file} 
@opindex --internal-links=@var{file}
In HTML mode, output a tab separated file containing three columns:
the internal link to an indexed item or item in the table of contents, 
the name of the index (or "toc") in which it occurs, and the term
which was indexed or entered.

@item --macro-expand=@var{file}
@itemx -E @var{file}
@opindex --macro-expand=@var{file}
@opindex -E @var{file}
Output the Texinfo source with all the macros expanded to the named
file.  Normally, the results of macro expansion are used internally by
@code{makeinfo} and then discarded.  This option is used by
@command{texi2dvi}.

@item --no-headers
@item --plaintext
@opindex --no-headers
@opindex --plaintext
@cindex Plain text output
@cindex ASCII text output
@cindex Generating plain text files
@cindex @file{INSTALL} file, generating
@cindex Node separators, omitting
@cindex Menus, omitting
Do not include menus or node separator lines in the output, and
implicitly @option{--enable-encoding} (see above).  This results in a
simple plain text file that you can (for example) send in email
without complications, or include in a distribution (as in an
@file{INSTALL} file).

@cindex Navigation links, omitting
For HTML output, likewise omit menus.  And if @samp{--no-split} is also
specified, do not include a navigation links at the top of each node
(these are never included in the default case of split output).
@xref{Generating HTML}.

In both cases, ignore @code{@@setfilename} and write to standard
output by default---can be overridden with @option{-o}.

@item --no-ifdocbook
@opindex --no-ifdocbook
@itemx --no-ifhtml
@opindex --no-ifhtml
@itemx --no-ifinfo
@opindex --no-ifinfo
@itemx --no-ifplaintext
@opindex --no-ifplaintext
@itemx --no-iftex
@opindex --no-iftex
@itemx --no-ifxml
@opindex --no-ifxml
Do not process @samp{@@if@var{format}} and @samp{@@@var{format}}
commands, and do process @samp{@@ifnot@var{format}}, even if
generating the given format.  For instance, if @option{--no-ifhtml} is
specified, then @samp{@@ifhtml} and @samp{@@html} blocks will not be
read, and @samp{@@ifnothtml} blocks will be.

@item --no-number-footnotes
@opindex --no-number-footnotes
Suppress automatic footnote numbering.  By default, @code{makeinfo}
numbers each footnote sequentially in a single node, resetting the
current footnote number to 1 at the start of each node.

@item --no-number-sections
@opindex --no-number-sections
Do not output chapter, section, and appendix numbers.
You need to specify this if your manual is not hierarchically-structured.

@item --no-split
@opindex --no-split
@cindex Splitting of output files
@cindex Output file splitting
Suppress the splitting stage of @code{makeinfo}.  By default, large
output files (where the size is greater than 70k bytes) are split into
smaller subfiles.  For Info output, each one is approximately 50k bytes.
For HTML output, each file contains one node (@pxref{Generating HTML}).

@item --no-pointer-validate
@itemx --no-validate
@opindex --no-pointer-validate
@opindex --no-validate
@cindex Pointer validation, suppressing
Suppress the pointer-validation phase of @code{makeinfo}---a dangerous
thing to do.  This can also be done with the @code{@@novalidate}
command (@pxref{Use TeX,,Use @TeX{}}).  Normally, after a Texinfo file
is processed, some consistency checks are made to ensure that cross
references can be resolved, etc.  @xref{Pointer Validation}.

@item --no-warn
@opindex --no-warn
Suppress warning messages (but @emph{not} error messages).

@item --number-sections
@opindex --number-sections
Output chapter, section, and appendix numbers as in printed manuals.
This is the default.  It works only with hierarchically-structured
manuals.

@item --output=@var{file}
@itemx -o @var{file}
@opindex --output=@var{file}
@opindex -o @var{file}
Specify that the output should be directed to @var{file} and not to the
file name specified in the @code{@@setfilename} command found in the
Texinfo source (@pxref{setfilename}).  If @var{file} is @samp{-}, output
goes to standard output and @samp{--no-split} is implied.  For split
HTML output, @var{file} is the name for the directory into which all
HTML nodes are written (@pxref{Generating HTML}).

@item -P @var{dir}
@opindex -P @var{dir}
Prepend @var{dir} to the directory search list for @code{@@include}.
If @var{dir} is not given, the current directory @file{.} is prepended.
See @samp{-I} for more details.

@item --paragraph-indent=@var{indent}
@itemx -p @var{indent}
@opindex --paragraph-indent=@var{indent}
@opindex -p @var{indent}
Set the paragraph indentation style to @var{indent}.  The value set by
this option overrides the value set in a Texinfo file by an
@code{@@paragraphindent} command (@pxref{paragraphindent}).  The value
of @var{indent} is interpreted as follows:

@table @asis
@item @samp{asis}
Preserve any existing indentation at the starts of paragraphs.

@item @samp{0} or @samp{none}
Delete any existing indentation.

@item @var{num}
Indent each paragraph by @var{num} spaces.
@end table

@item --split-size=@var{num}
@opindex --split-size=@var{num}
Keep Info files to at most @var{num} characters; default is 300,000.

@item --transliterate-file-names
@opindex --transliterate-file-names
Enable transliteration of 8-bit characters in node names for the
purpose of file name creation. @xref{HTML Xref 8-bit Character Expansion}.

@item -U @var{var}
Cause @var{var} to be undefined.  This is equivalent to
@code{@@clear @var{var}} in the Texinfo file (@pxref{set clear value}).

@item --verbose
@opindex --verbose
Cause @code{makeinfo} to display messages saying what it is doing.
Normally, @code{makeinfo} only outputs messages if there are errors or
warnings.

@item --version
@itemx -V
@opindex --version
@opindex -V
Print the version number, then exit successfully.

@item --xml
@opindex --xml
Generate XML output rather than Info.

@end table

@vindex TEXINFO_OUTPUT_FORMAT
@cindex Environment variable @code{TEXINFO_OUTPUT_FORMAT}
@command{makeinfo} also reads the environment variable
@env{TEXINFO_OUTPUT_FORMAT} to determine the output format, if not
overridden by a command line option.  The possible values are:

@example
docbook  html  info  plaintext  xml
@end example

If not set, Info output is the default.


@node Pointer Validation
@subsection Pointer Validation
@cindex Pointer validation with @code{makeinfo}
@cindex Validation of pointers

If you do not suppress pointer validation with the @samp{--no-validate}
option or the @code{@@novalidate} command in the source file (@pxref{Use
TeX,,Use @TeX{}}), @code{makeinfo} will check the validity of the final
Info file.  Mostly, this means ensuring that nodes you have referenced
really exist.  Here is a complete list of what is checked:

@enumerate
@item
If a `Next', `Previous', or `Up' node reference is a reference to a
node in the current file and is not an external reference such as to
@file{(dir)}, then the referenced node must exist.@refill

@item
In every node, if the `Previous' node is different from the `Up' node,
then the node pointed to by the `Previous' field must have a `Next'
field which points back to this node.@refill

@item
Every node except the `Top' node must have an `Up' pointer.@refill

@item
The node referenced by an `Up' pointer must itself reference the current
node through a menu item, unless the node referenced by `Up'
has the form `(@var{file})'.

@item
If the `Next' reference of a node is not the same as the `Next' reference
of the `Up' reference, then the node referenced by the `Next' pointer
must have a `Previous' pointer that points back to the current node.
This rule allows the last node in a section to point to the first node
of the next chapter.@refill

@item
Every node except `Top' should be referenced by at least one other node,
either via the `Previous' or `Next' links, or via a menu or a
cross-reference.@refill
@end enumerate

@cindex @@-commands in @@node, limited support
Some Texinfo documents might fail during the validation phase because
they use commands like @code{@@value} and @code{@@definfoenclose} in
node definitions and cross-references inconsistently.  (Your best bet
is to avoid using @@-commands in node names.)  Consider the
following example:

@example
@group
@@set nodename Node 1

@@node @@value@{nodename@}, Node 2, Top, Top

This is node 1.

@@node Node 2, , Node 1, Top

This is node 2.
@end group
@end example

@noindent
Here, the node ``Node 1'' was referenced both verbatim and through
@code{@@value}.

By default, @code{makeinfo} fails such cases, because node names are not
fully expanded until they are written to the output file.  You should
always try to reference nodes consistently; e.g., in the above example,
the second @code{@@node} line should have also used @code{@@value}.
However, if, for some reason, you @emph{must} reference node names
inconsistently, and @code{makeinfo} fails to validate the file, you can
use the @samp{--commands-in-node-names} option to force @code{makeinfo}
to perform the expensive expansion of all node names it finds in the
document.  This might considerably slow down the program, though;
twofold increase in conversion time was measured for large documents
such as the Jargon file.

@cindex @@value in @@node lines
The support for @code{@@}-commands in @code{@@node} directives is not
general enough to be freely used.  For example, if the example above
redefined @code{nodename} somewhere in the document, @code{makeinfo}
will fail to convert it, even if invoked with the
@samp{--commands-in-node-names} option.

@samp{--commands-in-node-names} has no effect if the @samp{--no-validate}
option is given.


@node makeinfo in Emacs
@subsection Running @code{makeinfo} Within Emacs
@cindex Running @code{makeinfo} in Emacs
@cindex @code{makeinfo} inside Emacs
@cindex Shell, running @code{makeinfo} in

You can run @code{makeinfo} in GNU Emacs Texinfo mode by using either the
@code{makeinfo-region} or the @code{makeinfo-buffer} commands.  In
Texinfo mode, the commands are bound to @kbd{C-c C-m C-r} and @kbd{C-c
C-m C-b} by default.@refill

@table @kbd
@item C-c C-m C-r
@itemx M-x makeinfo-region
Format the current region for Info.@refill
@findex makeinfo-region

@item C-c C-m C-b
@itemx M-x makeinfo-buffer
Format the current buffer for Info.@refill
@findex makeinfo-buffer
@end table

When you invoke @code{makeinfo-region} the output goes to a temporary
buffer.  When you invoke @code{makeinfo-buffer} output goes to the
file set with @code{@@setfilename} (@pxref{setfilename}).

The Emacs @code{makeinfo-region} and @code{makeinfo-buffer} commands
run the @code{makeinfo} program in a temporary shell buffer.  If
@code{makeinfo} finds any errors, Emacs displays the error messages in
the temporary buffer.@refill

@cindex Errors, parsing
@cindex Parsing errors
@findex next-error
You can parse the error messages by typing @kbd{C-x `}
(@code{next-error}).  This causes Emacs to go to and position the
cursor on the line in the Texinfo source that @code{makeinfo} thinks
caused the error.  @xref{Compilation, , Running @code{make} or
Compilers Generally, emacs, The GNU Emacs Manual}, for more
information about using the @code{next-error} command.@refill

In addition, you can kill the shell in which the @code{makeinfo}
command is running or make the shell buffer display its most recent
output.@refill

@table @kbd
@item C-c C-m C-k
@itemx M-x makeinfo-kill-job
@findex makeinfo-kill-job
Kill the current running @code{makeinfo} job
(from @code{makeinfo-region} or @code{makeinfo-buffer}).@refill

@item C-c C-m C-l
@itemx M-x makeinfo-recenter-output-buffer
@findex makeinfo-recenter-output-buffer
Redisplay the @code{makeinfo} shell buffer to display its most recent
output.@refill
@end table

@noindent
(Note that the parallel commands for killing and recentering a @TeX{}
job are @kbd{C-c C-t C-k} and @kbd{C-c C-t C-l}.  @xref{Texinfo Mode
Printing}.)@refill

You can specify options for @code{makeinfo} by setting the
@code{makeinfo-options} variable with either the @kbd{M-x
customize} or the @kbd{M-x set-variable} command, or by setting the
variable in your @file{.emacs} initialization file.

For example, you could write the following in your @file{.emacs} file:@refill

@example
@group
(setq makeinfo-options
     "--paragraph-indent=0 --no-split
      --fill-column=70 --verbose")
@end group
@end example

@noindent
@c If you write these three cross references using xref, you see
@c three references to the same named manual, which looks strange.
@iftex
For more information, see @ref{makeinfo options, , Options for
@code{makeinfo}}, as well as ``Easy Customization Interface,'' ``Examining
and Setting Variables,'' and ``Init File'' in @cite{The GNU Emacs
Manual}.
@end iftex
@ifnottex
For more information, see@*
@ref{Easy Customization, , Easy Customization Interface, emacs, The GNU Emacs Manual},@*
@ref{Examining, , Examining and Setting Variables, emacs, The GNU Emacs Manual},@*
@ref{Init File, , , emacs, The GNU Emacs Manual}, and@*
@ref{makeinfo options, , Options for @code{makeinfo}}.
@end ifnottex

@node texinfo-format commands
@subsection The @code{texinfo-format@dots{}} Commands

In GNU Emacs in Texinfo mode, you can format part or all of a Texinfo
file with the @code{texinfo-format-region} command.  This formats the
current region and displays the formatted text in a temporary buffer
called @samp{*Info Region*}.@refill

Similarly, you can format a buffer with the
@code{texinfo-format-buffer} command.  This command creates a new
buffer and generates the Info file in it.  Typing @kbd{C-x C-s} will
save the Info file under the name specified by the
@code{@@setfilename} line which must be near the beginning of the
Texinfo file.@refill

@table @kbd
@item C-c C-e C-r
@itemx @code{texinfo-format-region}
@findex texinfo-format-region
Format the current region for Info.

@item C-c C-e C-b
@itemx @code{texinfo-format-buffer}
@findex texinfo-format-buffer
Format the current buffer for Info.
@end table

The @code{texinfo-format-region} and @code{texinfo-format-buffer}
commands provide you with some error checking, and other functions can
provide you with further help in finding formatting errors.  These
procedures are described in an appendix; see @ref{Catching Mistakes}.
However, the @code{makeinfo} program is often faster and
provides better error checking (@pxref{makeinfo in Emacs}).@refill

@node Batch Formatting
@comment  node-name,  next,  previous,  up
@subsection Batch Formatting
@cindex Batch formatting for Info
@cindex Info batch formatting

You can format Texinfo files for Info using @code{batch-texinfo-format}
and Emacs Batch mode.  You can run Emacs in Batch mode from any shell,
including a shell inside of Emacs.  (@xref{Command Arguments,,,
emacs, The GNU Emacs Manual}.)

Here is a shell command to format all the files that end in
@file{.texinfo} in the current directory:

@example
emacs -batch -funcall batch-texinfo-format *.texinfo
@end example

@noindent
Emacs processes all the files listed on the command line, even if an
error occurs while attempting to format some of them.@refill

Run @code{batch-texinfo-format} only with Emacs in Batch mode as shown;
it is not interactive.  It kills the Batch mode Emacs on completion.@refill

@code{batch-texinfo-format} is convenient if you lack @code{makeinfo}
and want to format several Texinfo files at once.  When you use Batch
mode, you create a new Emacs process.  This frees your current Emacs, so
you can continue working in it.  (When you run
@code{texinfo-format-region} or @code{texinfo-format-buffer}, you cannot
use that Emacs for anything else until the command finishes.)@refill

@node Tag and Split Files
@comment  node-name,  next,  previous,  up
@subsection Tag Files and Split Files
@cindex Making a tag table automatically
@cindex Tag table, making automatically

If a Texinfo file has more than 30,000 bytes,
@code{texinfo-format-buffer} automatically creates a tag table
for its Info file;  @code{makeinfo} always creates a tag table.  With
a @dfn{tag table}, Info can jump to new nodes more quickly than it can
otherwise.@refill

@cindex Indirect subfiles
In addition, if the Texinfo file contains more than about 300,000
bytes, @code{texinfo-format-buffer} and @code{makeinfo} split the
large Info file into shorter @dfn{indirect} subfiles of about 300,000
bytes each.  Big files are split into smaller files so that Emacs does
not need to make a large buffer to hold the whole of a large Info
file; instead, Emacs allocates just enough memory for the small, split-off
file that is needed at the time.  This way, Emacs avoids wasting
memory when you run Info.  (Before splitting was implemented, Info
files were always kept short and @dfn{include files} were designed as
a way to create a single, large printed manual out of the smaller Info
files.  @xref{Include Files}, for more information.  Include files are
still used for very large documents, such as @cite{The Emacs Lisp
Reference Manual}, in which each chapter is a separate file.)@refill

When a file is split, Info itself makes use of a shortened version of
the original file that contains just the tag table and references to
the files that were split off.  The split-off files are called
@dfn{indirect} files.@refill

The split-off files have names that are created by appending @w{@samp{-1}},
@w{@samp{-2}}, @w{@samp{-3}} and so on to the file name specified by the
@code{@@setfilename} command.  The shortened version of the original file
continues to have the name specified by @code{@@setfilename}.@refill

At one stage in writing this document, for example, the Info file was saved
as the file @file{test-texinfo} and that file looked like this:@refill

@example
@group
Info file: test-texinfo,    -*-Text-*-
produced by texinfo-format-buffer
from file: new-texinfo-manual.texinfo

^_
Indirect:
test-texinfo-1: 102
test-texinfo-2: 50422
@end group
@group
test-texinfo-3: 101300
^_^L
Tag table:
(Indirect)
Node: overview^?104
Node: info file^?1271
@end group
@group
Node: printed manual^?4853
Node: conventions^?6855
@dots{}
@end group
@end example

@noindent
(But @file{test-texinfo} had far more nodes than are shown here.)  Each of
the split-off, indirect files, @file{test-texinfo-1},
@file{test-texinfo-2}, and @file{test-texinfo-3}, is listed in this file
after the line that says @samp{Indirect:}.  The tag table is listed after
the line that says @samp{Tag table:}. @refill

In the list of indirect files, the number following the file name
records the cumulative number of bytes in the preceding indirect files,
not counting the file list itself, the tag table, or the permissions
text in each file.  In the tag table, the number following the node name
records the location of the beginning of the node, in bytes from the
beginning of the (unsplit) output.

If you are using @code{texinfo-format-buffer} to create Info files,
you may want to run the @code{Info-validate} command.  (The
@code{makeinfo} command does such a good job on its own, you do not
need @code{Info-validate}.)  However, you cannot run the @kbd{M-x
Info-validate} node-checking command on indirect files.  For
information on how to prevent files from being split and how to
validate the structure of the nodes, see @ref{Using Info-validate}.


@node Installing an Info File
@section Installing an Info File
@cindex Installing an Info file
@cindex Info file installation
@cindex @file{dir} directory for Info installation

Info files are usually kept in the @file{info} directory.  You can read
Info files using the standalone Info program or the Info reader built
into Emacs.  (@inforef{Top, info, info}, for an introduction to Info.)

@menu
* Directory File::              The top level menu for all Info files.
* New Info File::               Listing a new Info file.
* Other Info Directories::      How to specify Info files that are
                                 located in other directories.
* Installing Dir Entries::      How to specify what menu entry to add
                                 to the Info directory.
* Invoking install-info::       @code{install-info} options.
@end menu


@node Directory File
@subsection The Directory File @file{dir}

For Info to work, the @file{info} directory must contain a file that
serves as a top level directory for the Info system.  By convention,
this file is called @file{dir}.  (You can find the location of this file
within Emacs by typing @kbd{C-h i} to enter Info and then typing
@kbd{C-x C-f} to see the pathname to the @file{info} directory.)

The @file{dir} file is itself an Info file.  It contains the top level
menu for all the Info files in the system.  The menu looks like
this:@refill

@example
@group
* Menu:
* Info:    (info).     Documentation browsing system.
* Emacs:   (emacs).    The extensible, self-documenting
                      text editor.
* Texinfo: (texinfo).  With one source file, make
                      either a printed manual using
                      @@TeX@{@} or an Info file.
@dots{}
@end group
@end example

Each of these menu entries points to the `Top' node of the Info file
that is named in parentheses.  (The menu entry does not need to
specify the `Top' node, since Info goes to the `Top' node if no node
name is mentioned.  @xref{Other Info Files, , Nodes in Other Info
Files}.)@refill

Thus, the @samp{Info} entry points to the `Top' node of the
@file{info} file and the @samp{Emacs} entry points to the `Top' node
of the @file{emacs} file.@refill

In each of the Info files, the `Up' pointer of the `Top' node refers
back to the @code{dir} file.  For example, the line for the `Top'
node of the Emacs manual looks like this in Info:@refill

@example
File: emacs  Node: Top, Up: (DIR), Next: Distrib
@end example

@noindent
In this case, the @file{dir} file name is written in upper case
letters---it can be written in either upper or lower case.  This is not
true in general, it is a special case for @file{dir}.


@node New Info File
@subsection Listing a New Info File
@cindex Adding a new Info file
@cindex Listing a new Info file
@cindex New Info file, listing it in @file{dir} file
@cindex Info file, listing a new
@cindex @file{dir} file listing

To add a new Info file to your system, you must write a menu entry to
add to the menu in the @file{dir} file in the @file{info} directory.
For example, if you were adding documentation for GDB, you would write
the following new entry:@refill

@example
* GDB: (gdb).           The source-level C debugger.
@end example

@noindent
The first part of the menu entry is the menu entry name, followed by a
colon.  The second part is the name of the Info file, in parentheses,
followed by a period.  The third part is the description.

The name of an Info file often has a @file{.info} extension.  Thus, the
Info file for GDB might be called either @file{gdb} or @file{gdb.info}.
The Info reader programs automatically try the file name both with and
without @file{.info}@footnote{On MS-DOS/MS-Windows systems, Info will
try the @file{.inf} extension as well.}; so it is better to avoid
clutter and not to write @samp{.info} explicitly in the menu entry.  For
example, the GDB menu entry should use just @samp{gdb} for the file
name, not @samp{gdb.info}.


@node Other Info Directories
@subsection Info Files in Other Directories
@cindex Installing Info in another directory
@cindex Info installed in another directory
@cindex Another Info directory
@cindex @file{dir} files and Info directories

If an Info file is not in the @file{info} directory, there are three
ways to specify its location:@refill

@enumerate
@item
Write the pathname in the @file{dir} file as the second part of the menu.

@item
If you are using Emacs, list the name of the file in a second @file{dir}
file, in its directory; and then add the name of that directory to the
@code{Info-directory-list} variable in your personal or site
initialization file.

This variable tells Emacs where to look for @file{dir} files (the files
must be named @file{dir}).  Emacs merges the files named @file{dir} from
each of the listed directories.  (In Emacs version 18, you can set the
@code{Info-directory} variable to the name of only one
directory.)@refill

@item
Specify the Info directory name in the @code{INFOPATH} environment
variable in your @file{.profile} or @file{.cshrc} initialization file.
(Only you and others who set this environment variable will be able to
find Info files whose location is specified this way.)
@end enumerate

For example, to reach a test file in the @file{/home/bob/info}
directory, you could add an entry like this to the menu in the
standard @file{dir} file:@refill

@example
* Test: (/home/bob/info/info-test).  Bob's own test file.
@end example

@noindent
In this case, the absolute file name of the @file{info-test} file is
written as the second part of the menu entry.@refill

Alternatively, you could write the following in your @file{.emacs} file:

@vindex Info-directory-list
@example
@group
(require 'info)
(setq Info-directory-list
 (cons (expand-file-name "/home/bob/info")
       Info-directory-list))
@end group
@end example

This tells Emacs to merge the system @file{dir} file with the @file{dir}
file in @file{/home/bob/info}.  Thus, Info will list the
@file{/home/bob/info/info-test} file as a menu entry in the
@file{/home/bob/info/dir} file.  Emacs does the merging only when
@kbd{M-x info} is first run, so if you want to set
@code{Info-directory-list} in an Emacs session where you've already run
@code{info}, you must @code{(setq Info-dir-contents nil)} to force Emacs
to recompose the @file{dir} file.

@vindex INFOPATH
@cindex Environment variable @code{INFOPATH}
Finally, you can tell Info where to look by setting the @code{INFOPATH}
environment variable in your shell startup file, such as @file{.cshrc},
@file{.profile} or @file{autoexec.bat}.  If you use a Bourne-compatible
shell such as @code{sh} or @code{bash} for your shell command
interpreter, you set the @code{INFOPATH} environment variable in the
@file{.profile} initialization file; but if you use @code{csh} or
@code{tcsh}, you set the variable in the @file{.cshrc} initialization
file.  On MS-DOS/MS-Windows systems, you must set @code{INFOPATH} in
your @file{autoexec.bat} file or in the Registry.  Each type of shell
uses a different syntax.

@itemize @bullet
@item
In a @file{.cshrc} file, you could set the @code{INFOPATH}
variable as follows:@refill

@smallexample
setenv INFOPATH .:~/info:/usr/local/emacs/info
@end smallexample

@item
In a @file{.profile} file, you would achieve the same effect by
writing:@refill

@smallexample
INFOPATH=.:$HOME/info:/usr/local/emacs/info
export INFOPATH
@end smallexample

@item
@pindex autoexec.bat
In a @file{autoexec.bat} file, you write this command@footnote{Note the
use of @samp{;} as the directory separator, and a different syntax for
using values of other environment variables.}:

@smallexample
set INFOPATH=.;%HOME%/info;c:/usr/local/emacs/info
@end smallexample
@end itemize

@noindent
The @samp{.} indicates the current directory as usual.  Emacs uses the
@code{INFOPATH} environment variable to initialize the value of Emacs's
own @code{Info-directory-list} variable.  The stand-alone Info reader
merges any files named @file{dir} in any directory listed in the
@env{INFOPATH} variable into a single menu presented to you in the node
called @samp{(dir)Top}.

@cindex Colon, last in @env{INFOPATH}
However you set @env{INFOPATH}, if its last character is a
colon@footnote{On MS-DOS/MS-Windows systems, use semi-colon instead.}, this
is replaced by the default (compiled-in) path.  This gives you a way to
augment the default path with new directories without having to list all
the standard places.  For example (using @code{sh} syntax):

@example
INFOPATH=/local/info:
export INFOPATH
@end example

@noindent
will search @file{/local/info} first, then the standard directories.
Leading or doubled colons are not treated specially.

@cindex @file{dir} file, creating your own
When you create your own @file{dir} file for use with
@code{Info-directory-list} or @env{INFOPATH}, it's easiest to start by
copying an existing @file{dir} file and replace all the text after the
@samp{* Menu:} with your desired entries.  That way, the punctuation and
special CTRL-_ characters that Info needs will be present.


@node Installing Dir Entries
@subsection Installing Info Directory Files

When you install an Info file onto your system, you can use the program
@code{install-info} to update the Info directory file @file{dir}.
Normally the makefile for the package runs @code{install-info}, just
after copying the Info file into its proper installed location.

@findex dircategory
@findex direntry
In order for the Info file to work with @code{install-info}, you include
the commands @code{@@dircategory} and
@code{@@direntry}@dots{}@code{@@end direntry} in the Texinfo source
file.  Use @code{@@direntry} to specify the menu entries to add to the
Info directory file, and use @code{@@dircategory} to specify which part
of the Info directory to put it in.  Here is how these commands are used
in this manual:

@smallexample
@@dircategory Texinfo documentation system
@@direntry
* Texinfo: (texinfo).           The GNU documentation format.
* install-info: (texinfo)Invoking install-info. @dots{}
@dots{}
@@end direntry
@end smallexample

Here's what this produces in the Info file:

@smallexample
INFO-DIR-SECTION Texinfo documentation system
START-INFO-DIR-ENTRY
* Texinfo: (texinfo).           The GNU documentation format.
* install-info: (texinfo)Invoking install-info. @dots{}
@dots{}
END-INFO-DIR-ENTRY
@end smallexample

@noindent
The @code{install-info} program sees these lines in the Info file, and
that is how it knows what to do.

Always use the @code{@@direntry} and @code{@@dircategory} commands near
the beginning of the Texinfo input, before the first @code{@@node}
command.  If you use them later on in the input, @code{install-info}
will not notice them.

@code{install-info} will automatically reformat the description of the
menu entries it is adding.  As a matter of convention, the description
of the main entry (above, @samp{The GNU documentation format}) should
start at column 32, starting at zero (as in
@code{what-cursor-position} in Emacs).  This will make it align with
most others.  Description for individual utilities best start in
column 48, where possible.  For more information about formatting see
the @samp{--calign}, @samp{--align}, and @samp{--max-width} options in
@ref{Invoking install-info}.

If you use @code{@@dircategory} more than once in the Texinfo source,
each usage specifies the `current' category; any subsequent
@code{@@direntry} commands will add to that category.

@cindex Free Software Directory
@cindex Dir categories, choosing
@cindex Categories, choosing
When choosing a category name for the @code{@@dircategory} command, we
recommend consulting the @uref{http://www.gnu.org/directory,
Free Software Directory}.  If your program is not listed there,
or listed incorrectly or incompletely, please report the situation to
the directory maintainers (@email{bug-directory@@gnu.org}) so that the
category names can be kept in sync.

Here are a few examples (see the @file{util/dir-example} file in the
Texinfo distribution for large sample @code{dir} file):

@display
Emacs
Localization
Printing
Software development
Software libraries
Text creation and manipulation
@end display

@cindex Invoking nodes, including in dir file
Each `Invoking' node for every program installed should have a
corresponding @code{@@direntry}.  This lets users easily find the
documentation for the different programs they can run, as with the
traditional @command{man} system.


@node Invoking install-info
@subsection Invoking @command{install-info}
@pindex install-info

@code{install-info} inserts menu entries from an Info file into the
top-level @file{dir} file in the Info system (see the previous sections
for an explanation of how the @file{dir} file works).  @code{install-info} 
also removes menu entries from the @file{dir} file.  It's most often
run as part of software installation, or when constructing a @file{dir} file
for all manuals on a system.  Synopsis:

@example
install-info [@var{option}]@dots{} [@var{info-file} [@var{dir-file}]]
@end example

If @var{info-file} or @var{dir-file} are not specified, the options
(described below) that define them must be.  There are no compile-time
defaults, and standard input is never used.  @code{install-info} can
read only one Info file and write only one @file{dir} file per invocation.

@cindex @file{dir}, created by @code{install-info}
If @var{dir-file} (however specified) does not exist,
@code{install-info} creates it if possible (with no entries).

@cindex Compressed dir files, reading
@cindex Bzipped dir files, reading
@cindex LZMA-compressed dir files, reading
@cindex Dir files, compressed
If any input file is compressed with @code{gzip} (@pxref{Top,,,gzip,
Gzip}), @code{install-info} automatically uncompresses it
for reading.  And if @var{dir-file} is compressed, @code{install-info}
also automatically leaves it compressed after writing any changes.
If @var{dir-file} itself does not exist, @code{install-info} tries to
open @file{@var{dir-file}.gz}, @file{@var{dir-file}.bz2}, and 
@file{@var{dir-file}.lzma}, in that order.

Options:

@table @code
@item --add-once
Specifies that the entry or entries will only be put into a single section.

@item --align=@var{column}
@opindex --align=@var{column}
Specifies the column that the second and subsequent lines of menu entry's 
description will be formatted to begin at.  The default for this option is 
@samp{35}.  It is used in conjunction with the @samp{--max-width} option.
@var{column} starts counting at 1.

@item --append-new-sections
Instead of alphabetizing new sections, place them at the end of the DIR file.

@item --calign=@var{column}
@opindex --calign=@var{column}
Specifies the column that the first line of menu entry's description will 
be formatted to begin at.  The default for this option is @samp{33}.  It is 
used in conjunction with the @samp{--max-width} option.
When the name of the menu entry exceeds this column, entry's description 
will start on the following line.
@var{column} starts counting at 1.

@item --debug
@opindex --debug
Report what is being done.

@item --delete
@opindex --delete
Delete the entries in @var{info-file} from @var{dir-file}.  The file
name in the entry in @var{dir-file} must be @var{info-file} (except for
an optional @samp{.info} in either one).  Don't insert any new entries.
Any empty sections that result from the removal are also removed.

@item --description=@var{text}
@opindex --description=@var{text}
Specify the explanatory portion of the menu entry.  If you don't specify
a description (either via @samp{--entry}, @samp{--item} or this option),
the description is taken from the Info file itself.

@item --dir-file=@var{name}
@opindex --dir-file=@var{name}
Specify file name of the Info directory file.  This is equivalent to
using the @var{dir-file} argument.

@item --dry-run
@opindex --dry-run
Same as @samp{--test}.

@item --entry=@var{text}
@opindex --entry=@var{text}
Insert @var{text} as an Info directory entry; @var{text} should have the
form of an Info menu item line plus zero or more extra lines starting
with whitespace.  If you specify more than one entry, they are all
added.  If you don't specify any entries, they are determined from
information in the Info file itself.

@item --help
@opindex --help
Display a usage message with basic usage and all available options,
then exit successfully.

@item --info-file=@var{file}
@opindex --info-file=@var{file}
Specify Info file to install in the directory.  This is
equivalent to using the @var{info-file} argument.

@item --info-dir=@var{dir}
@opindex --info-dir=@var{dir}
Specify the directory where the directory file @file{dir} resides.
Equivalent to @samp{--dir-file=@var{dir}/dir}.

@item --infodir=@var{dir}
@opindex --infodir=@var{dir}
Same as @samp{--info-dir}.

@item --item=@var{text}
@opindex --item=@var{text}
Same as @samp{--entry=@var{text}}.  An Info directory entry is actually
a menu item.

@item --keep-old
@opindex --keep-old
Do not replace pre-existing menu entries.  When @samp{--remove} is specified, 
this option means that empty sections are not removed.

@item --max-width=@var{column}
@opindex --max-width=@var{column}
Specifies the column that the menu entry's description will be word-wrapped
at.  @var{column} starts counting at 1.

@item --maxwidth=@var{column}
@opindex --maxwidth=@var{column}
Same as @samp{--max-width}.

@item --menuentry=@var{text}
@opindex --menuentry=@var{text}
Same as @samp{--name}.

@item --name=@var{text}
@opindex --name=@var{text}
Specify the name portion of the menu entry.  If the @var{text} does
not start with an asterisk @samp{*}, it is presumed to be the text
after the @samp{*} and before the parentheses that specify the Info
file.  Otherwise @var{text} is taken verbatim, and is taken as
defining the text up to and including the first period (a space is
appended if necessary).  If you don't specify the name (either via
@samp{--entry}, @samp{--item} or this option), it is taken from the
Info file itself.  If the Info does not contain the name, the basename
of the Info file is used.

@item --no-indent
@opindex --no-indent
Suppress formatting of new entries into the @file{dir} file.

@item --quiet
@opindex --quiet
@itemx --silent
@opindex --silent
Suppress warnings, etc., for silent operation.

@item --remove
@opindex --remove
Same as @samp{--delete}.

@item --remove-exactly
@opindex --remove-exactly
Also like @samp{--delete}, but only entries if the Info file name
matches exactly; @code{.info} and/or @code{.gz} suffixes are
@emph{not} ignored.

@item --section=@var{sec}
@opindex --section=@var{sec}
Put this file's entries in section @var{sec} of the directory.  If you
specify more than one section, all the entries are added in each of the
sections.  If you don't specify any sections, they are determined from
information in the Info file itself.  If the Info file doesn't specify
a section, the menu entries are put into the Miscellaneous section.

@item --section @var{regex} @var{sec}
@opindex --section @var{regex} @var{sec}
Same as @samp{--regex=@var{regex} --section=@var{sec} --add-once}.

@code{install-info} tries to detect when this alternate syntax is used, 
but does not always guess correctly.  Here is the heuristic that 
@code{install-info} uses:
@enumerate
@item
If the second argument to @code{--section} starts with a hyphen, the
original syntax is presumed.
@item
If the second argument to @code{--section} is a file that can be
opened, the original syntax is presumed.
@item
Otherwise the alternate syntax is used.
@end enumerate

When heuristic fails because your section title starts with a hyphen, or it 
happens to be a filename that can be opened, the syntax should be changed 
to @samp{--regex=@var{regex} --section=@var{sec} --add-once}.


@item --regex=@var{regex}
@opindex  --regex=@var{regex}
Put this file's entries into any section that matches @var{regex}.  If
more than one section matches, all of the entries are added in each of the
sections.  Specify @var{regex} using basic regular expression syntax, more 
or less as used with @command{grep}, for example.

@item --test
@opindex --test
Suppress updating of the directory file.

@item --version
@opindex --version
@cindex Version number, for install-info
Display version information and exit successfully.

@end table


@node Generating HTML
@chapter Generating HTML
@cindex HTML output

@command{makeinfo} generates Info output by default, but given the
@option{--html} option, it will generate HTML, for web browsers and
other programs.  This chapter gives some details on such HTML output.


@command{makeinfo} can also write in XML and Docbook format, but we do
not as yet describe these further.  @xref{Output Formats}, for a brief
overview of all the output formats.

@menu
* HTML Translation::       Details of the HTML output.
* HTML Splitting::         How HTML output is split.
* HTML CSS::               Influencing HTML output with Cascading Style Sheets.
* HTML Xref::              Cross-references in HTML output.
@end menu


@node HTML Translation
@section HTML Translation

@command{makeinfo} will include segments of Texinfo source between
@code{@@ifhtml} and @code{@@end ifhtml} in the HTML output (but not
any of the other conditionals, by default).  Source between
@code{@@html} and @code{@@end html} is passed without change to the
output (i.e., suppressing the normal escaping of input @samp{<},
@samp{>} and @samp{&} characters which have special significance in
HTML).  @xref{Conditional Commands}.

@opindex --footnote-style@r{, ignored in HTML output}
The @option{--footnote-style} option is currently ignored for HTML output;
footnotes are always linked to the end of the output file.

@cindex Navigation bar, in HTML output
By default, a navigation bar is inserted at the start of each node,
analogous to Info output.  The @samp{--no-headers} option suppresses
this if used with @samp{--no-split}.  Header @code{<link>} elements in
split output can support info-like navigation with browsers like Lynx
and @w{Emacs W3} which implement this HTML@tie{}1.0 feature.

@cindex HTML output, browser compatibility of
The HTML generated is mostly standard (i.e., HTML@tie{}2.0, RFC-1866).
One exception is that HTML@tie{}3.2 tables are generated from the
@code{@@multitable} command, but tagged to degrade as well as possible
in browsers without table support.  The HTML@tie{}4 @samp{lang}
attribute on the @samp{<html>} attribute is also used.  (Please report
output from an error-free run of @code{makeinfo} which has browser
portability problems as a bug.)


@node HTML Splitting
@section HTML Splitting
@cindex Split HTML output
@cindex HTML output, split

When splitting output (which is the default), @command{makeinfo}
writes HTML output into (generally) one output file per Texinfo source
@code{@@node}.

The output file name is the node name with special characters replaced
by @samp{-}'s, so it can work as a filename.  In the unusual case of
two different nodes having the same name after this treatment, they
are written consecutively to the same file, with HTML anchors so each
can be referred to separately.  If @command{makeinfo} is run on a
system which does not distinguish case in filenames, nodes which are
the same except for case will also be folded into the same output
file.

When splitting, the HTML output files are written into a subdirectory,
with the name chosen as follows:
@enumerate
@item 
@command{makeinfo} first tries the subdirectory with the base name
from @code{@@setfilename} (that is, any extension is removed).  For
example, HTML output for @code{@@setfilename gcc.info} would be
written into a subdirectory named @samp{gcc}.

@item
If that directory cannot be created for any reason, then
@command{makeinfo} tries appending @samp{.html} to the directory name.
For example, output for @code{@@setfilename texinfo} would be written
to @samp{texinfo.html}.

@item
If the @samp{@var{name}.html} directory can't be
created either, @code{makeinfo} gives up.

@end enumerate

@noindent In any case, the top-level output file within the directory
is always named @samp{index.html}.

Monolithic output (@code{--no-split}) is named according to
@code{@@setfilename} (with any @samp{.info} extension is replaced with
@samp{.html}) or @code{--output} (the argument is used literally).


@node HTML CSS
@section HTML CSS
@cindex HTML, and CSS
@cindex CSS, and HTML output
@cindex Cascading Style Sheets, and HTML output

Cascading Style Sheets (CSS for short) is an Internet standard for
influencing the display of HTML documents: see
@uref{http://www.w3.org/Style/CSS/}.

By default, @command{makeinfo} includes a few simple CSS commands to
better implement the appearance of some of the environments.  Here 
are two of them, as an example:

@example
pre.display @{ font-family:inherit @}
pre.smalldisplay @{ font-family:inherit; font-size:smaller @}
@end example

A full explanation of CSS is (far) beyond this manual; please see the
reference above.  In brief, however, this specification tells the web
browser to use a `smaller' font size for @code{@@smalldisplay} text,
and to use the `inherited' font (generally a regular roman typeface)
for both @code{@@smalldisplay} and @code{@@display}.  By default, the
HTML @samp{<pre>} command uses a monospaced font.

You can influence the CSS in the HTML output with two
@command{makeinfo} options: @option{--css-include=@var{file}} and
@option{--css-ref=@var{url}}.

The option @option{--css-ref=@var{url}} adds to each output HTML file
a @samp{<link>} tag referencing a CSS at the given @var{url}. This
allows using external style sheets.

The option @option{--css-include=@var{file}} includes the contents
@var{file} in the HTML output, as you might expect.  However, the
details are somewhat tricky, as described in the following, to provide
maximum flexibility. 

@cindex @@import specifications, in CSS files
The CSS file may begin with so-called @samp{@@import} directives,
which link to external CSS specifications for browsers to use when
interpreting the document.  Again, a full description is beyond our
scope here, but we'll describe how they work syntactically, so we can
explain how @command{makeinfo} handles them.

@cindex Comments, in CSS files
There can be more than one @samp{@@import}, but they have to come
first in the file, with only whitespace and comments interspersed, no
normal definitions.  (Technical exception: an @samp{@@charset}
directive may precede the @samp{@@import}'s.  This does not alter
@command{makeinfo}'s behavior, it just copies the @samp{@@charset} if
present.)  Comments in CSS files are delimited by @samp{/* ... */}, as
in C.  An @samp{@@import} directive must be in one of these two forms:

@example
@@import url(http://example.org/foo.css);
@@import "http://example.net/bar.css";
@end example

As far as @command{makeinfo} is concerned, the crucial characters are
the @samp{@@} at the beginning and the semicolon terminating the
directive.  When reading the CSS file, it simply copies any such
@samp{@@}-directive into the output, as follows:

@itemize
@item If @var{file} contains only normal CSS declarations, it is
included after @command{makeinfo}'s default CSS, thus overriding it.

@item If @var{file} begins with @samp{@@import} specifications (see
below), then the @samp{import}'s are included first (they have to come
first, according to the standard), and then @command{makeinfo}'s
default CSS is included.  If you need to override @command{makeinfo}'s
defaults from an @samp{@@import}, you can do so with the @samp{!@:
important} CSS construct, as in:
@example
pre.smallexample @{ font-size: inherit ! important @}
@end example

@item If @var{file} contains both @samp{@@import} and inline CSS
specifications, the @samp{@@import}'s are included first, then
@command{makeinfo}'s defaults, and lastly the inline CSS from
@var{file}.

@item Any @@-directive other than @samp{@@import} and @samp{@@charset}
is treated as a CSS declaration, meaning @command{makeinfo} includes
its default CSS and then the rest of the file.

@end itemize

If the CSS file is malformed or erroneous, @command{makeinfo}'s output
is unspecified.  @command{makeinfo} does not try to interpret the
meaning of the CSS file in any way; it just looks for the special
@samp{@@} and @samp{;} characters and blindly copies the text into the
output.  Comments in the CSS file may or may not be included in the
output.


@node HTML Xref
@section HTML Cross-references
@cindex HTML cross-references
@cindex Cross-references, in HTML output

Cross-references between Texinfo manuals in HTML format amount, in the
end, to a standard HTML @code{<a>} link, but the details are
unfortunately complex.  This section describes the algorithm used in
detail, so that Texinfo can cooperate with other programs, such as
@command{texi2html}, by writing mutually compatible HTML files.

This algorithm may or may not be used for links @emph{within} HTML
output for a Texinfo file.  Since no issues of compatibility arise in
such cases, we do not need to specify this.

We try to support references to such ``external'' manuals in both
monolithic and split forms.  A @dfn{monolithic} (mono) manual is
entirely contained in one file, and a @dfn{split} manual has a file
for each node.  (@xref{HTML Splitting}.)

@cindex Dumas, Patrice
Acknowledgement: this algorithm was primarily devised by Patrice Dumas
in 2003--04.

@menu
* Link Basics:       HTML Xref Link Basics.
* Node Expansion:    HTML Xref Node Name Expansion.
* Command Expansion: HTML Xref Command Expansion.
* 8-bit Expansion:   HTML Xref 8-bit Character Expansion.
* Mismatch:          HTML Xref Mismatch.
@end menu


@node HTML Xref Link Basics
@subsection HTML Cross-reference Link Basics
@cindex HTML cross-reference link basics

For our purposes, an HTML link consists of four components: a host
name, a directory part, a file part, and a target part.  We
always assume the @code{http} protocol.  For example:

@example
http://@var{host}/@var{dir}/@var{file}.html#@var{target}
@end example

The information to construct a link comes from the node name and
manual name in the cross-reference command in the Texinfo source
(@pxref{Cross References}), and from @dfn{external information}, which
is currently simply hardwired.  In the future, it may come from an
external data file.

We now consider each part in turn.

The @var{host} is hardwired to be the local host.  This could either
be the literal string @samp{localhost}, or, according to the rules for
HTML links, the @samp{http://localhost/} could be omitted entirely.

The @var{dir} and @var{file} parts are more complicated, and depend on
the relative split/mono nature of both the manual being processed and
the manual that the cross-reference refers to.  The underlying idea is
that there is one directory for Texinfo manuals in HTML, and a given
@var{manual} is either available as a monolithic file
@file{@var{manual}.html}, or a split subdirectory
@file{@var{manual}/*.html}.  Here are the cases:

@itemize @bullet
@item
If the present manual is split, and the referent manual is also split,
the directory is @samp{../@var{referent/}} and the file is the
expanded node name (described later).

@item
If the present manual is split, and the referent manual is mono, the
directory is @samp{../} and the file is @file{@var{referent}.html}.

@item
If the present manual is mono, and the referent manual is split, the
directory is @file{@var{referent}/} and the file is the expanded node
name.

@item
If the present manual is mono, and the referent manual is also mono,
the directory is @file{./} (or just the empty string), and the file is
@file{@var{referent}.html}.

@end itemize

One exception: the algorithm for node name expansion prefixes the
string @samp{g_t} when the node name begins with a non-letter.  This
kludge (due to XHTML rules) is not necessary for filenames, and is
therefore omitted.

Any directory part in the filename argument of the source
cross-reference command is ignored.  Thus, @code{@@xref@{,,,../foo@}}
and @code{@@xref@{,,,foo@}} both use @samp{foo} as the manual name.
This is because any such attempted hardwiring of the directory is very
unlikely to be useful for both Info and HTML output.

Finally, the @var{target} part is always the expanded node name.

Whether the present manual is split or mono is determined by user
option; @command{makeinfo} defaults to split, with the
@option{--no-split} option overriding this.

Whether the referent manual is split or mono is another bit of the
external information.  For now, @command{makeinfo} simply assumes the
referent manual is the same as the present manual.

There can be a mismatch between the format of the referent manual that
the generating software assumes, and the format it's actually present
in.  @xref{HTML Xref Mismatch}.


@node HTML Xref Node Name Expansion
@subsection HTML Cross-reference Node Name Expansion
@cindex HTML cross-reference node name expansion
@cindex node name expansion, in HTML cross-references
@cindex expansion, of node names in HTML cross-references

As mentioned in the previous section, the key part of the HTML
cross-reference algorithm is the conversion of node names in the
Texinfo source into strings suitable for XHTML identifiers and
filenames.  The restrictions are similar for each: plain ASCII
letters, numbers, and the @samp{-} and @samp{_} characters are all
that can be used.  (Although HTML anchors can contain most characters,
XHTML is more restrictive.)

Cross-references in Texinfo can actually refer either to nodes or
anchors (@pxref{anchor}), but anchors are treated identically to nodes
in this context, so we'll continue to say ``node'' names for
simplicity.

(@@-commands and 8-bit characters are not presently handled by
@command{makeinfo} for HTML cross-references.  See the next section.)

A special exception: the Top node (@pxref{The Top Node}) is always
mapped to the file @file{index.html}, to match web server software.
However, the HTML @emph{target} is @samp{Top}.  Thus (in the split case):

@example
@@xref@{Top, Introduction,, emacs, The GNU Emacs Manual@}.
@result{} <a href="emacs/index.html#Top">
@end example

@enumerate
@item
The standard ASCII letters (a-z and A-Z) are not modified.  All other
characters are changed as specified below.

@item
The standard ASCII numbers (0-9) are not modified except when a number
is the first character of the node name.  In that case, see below.

@item
Multiple consecutive space, tab and newline characters are transformed
into just one space.  (It's not possible to have newlines in node
names with the current implementation, but we specify it anyway, just
in case.)

@item
Leading and trailing spaces are removed.

@item
After the above has been applied, each remaining space character is
converted into a @samp{-} character.

@item
Other ASCII 7-bit characters are transformed into @samp{_00@var{xx}},
where @var{xx} is the ASCII character code in (lowercase) hexadecimal.
This includes @samp{_}, which is mapped to @samp{_005f}.

@item
If the node name does not begin with a letter, the literal string
@samp{g_t} is prefixed to the result.  (Due to the rules above, that
string can never occur otherwise; it is an arbitrary choice, standing
for ``GNU Texinfo''.)  This is necessary because XHTML requires that
identifiers begin with a letter.

@end enumerate

For example:

@example
@@node A  node --- with _'%
@result{} A-node-_002d_002d_002d-with-_005f_0027_0025
@end example

Notice in particular:

@itemize @bullet
@item @samp{_} @result{} @samp{_005f}
@item @samp{-} @result{} @samp{_002d}
@item @samp{A  node} @result{} @samp{A-node}
@end itemize

On case-folding computer systems, nodes differing only by case will be
mapped to the same file.  

In particular, as mentioned above, Top always maps to the file
@file{index.html}.  Thus, on a case-folding system, Top and a node
named `Index' will both be written to @file{index.html}.

Fortunately, the targets serve to distinguish these cases, since HTML
target names are always case-sensitive, independent of operating
system.


@node HTML Xref Command Expansion
@subsection HTML Cross-reference Command Expansion
@cindex HTML cross-reference command expansion

In standard Texinfo, node names may not contain @@-commands.
@command{makeinfo} has an option @option{--commands-in-node-names}
which partially supports it (@pxref{Invoking makeinfo}), but it is not
robust and not recommended.

Thus, @command{makeinfo} does not fully implement this part of the
HTML cross-reference algorithm, but it is documented here for the sake
of completeness.

First, comments are removed.

Next, any @code{@@value} commands (@pxref{set value}) and macro invocations
(@pxref{Invoking Macros}) are fully expanded.

Then, for the following commands, the command name and braces are removed,
the text of the argument is recursively transformed:
@example
@@asis @@b @@cite @@code @@command @@dfn @@dmn @@dotless
@@emph @@env @@file @@indicateurl @@kbd @@key
@@samp @@sc @@slanted @@strong @@t @@var @@w
@end example

@noindent For @code{@@sc}, any letters are capitalized.

The following commands are replaced by constant text, as shown.  If
any of these commands have non-empty arguments, as in
@code{@@TeX@{bad@}}, it is an error, and the result is unspecified.
`(space)' means a space character, `(nothing)' means the empty string,
etc.  The notation `U+@var{xxxx}' means Unicode code point @var{xxxx}
(in hex, as usual).  There are further transformations of many of
these expansions for the final file or target name, such as space
characters to @samp{-}, etc., according to the other rules.

@multitable @columnfractions .3 .5
@item @code{@@(newline)}        @tab (space)
@item @code{@@(space)}          @tab (space)
@item @code{@@(tab)}            @tab (space)
@item @code{@@!}                @tab @samp{!}
@item @code{@@*}                @tab (space)
@item @code{@@-}                @tab (nothing)
@item @code{@@.}                @tab @samp{.}
@item @code{@@:}                @tab (nothing)
@item @code{@@?}                @tab @samp{?}
@item @code{@@@@}               @tab @samp{@@}
@item @code{@@@{}               @tab @samp{@{}
@item @code{@@@}}               @tab @samp{@}}
@item @code{@@LaTeX}            @tab @samp{LaTeX}
@item @code{@@TeX}              @tab @samp{TeX}
@item @code{@@arrow}            @tab U+2192
@item @code{@@bullet}           @tab U+2022
@item @code{@@comma}            @tab @samp{,}
@item @code{@@copyright}        @tab U+00A9
@item @code{@@dots}             @tab U+2026
@item @code{@@enddots}          @tab @samp{...}
@item @code{@@equiv}            @tab U+2261
@item @code{@@error}            @tab @samp{error-->}
@item @code{@@euro}             @tab U+20AC
@item @code{@@exclamdown}       @tab U+00A1
@item @code{@@expansion}        @tab U+2192
@item @code{@@geq}              @tab U+2265
@item @code{@@leq}              @tab U+2264
@item @code{@@minus}            @tab U+2212
@item @code{@@ordf}             @tab U+00AA
@item @code{@@ordm}             @tab U+00BA
@item @code{@@point}            @tab U+2605
@item @code{@@pounds}           @tab U+00A3
@item @code{@@print}            @tab U+22A3
@item @code{@@questiondown}     @tab U+00BF
@item @code{@@registeredsymbol} @tab U+00AE
@item @code{@@result}           @tab U+21D2
@item @code{@@textdegree}       @tab U+00B0
@item @code{@@tie}              @tab (space)
@end multitable

Quotation mark commands are likewise replaced by their Unicode values
(@pxref{Inserting Quotation Marks}).

An @code{@@acronym} or @code{@@abbr} command is replaced by the first
argument, followed by the second argument in parentheses, if present.
@xref{acronym}.

An @code{@@email} command is replaced by the @var{text} argument if
present, else the address.  @xref{email}.

An @code{@@image} command is replaced by the filename (first)
argument.  @xref{Images}.

A @code{@@verb} command is replaced by its transformed argument.
@xref{verb}.

Any other command is an error, and the result is unspecified.


@node HTML Xref 8-bit Character Expansion
@subsection HTML Cross-reference 8-bit Character Expansion
@cindex HTML cross-reference 8-bit character expansion
@cindex 8-bit characters, in HTML cross-references
@cindex Expansion of 8-bit characters in HTML cross-references
@cindex Transliteration of 8-bit characters in HTML cross-references

Usually, characters other than plain 7-bit ASCII are transformed into
the corresponding Unicode code point(s) in Normalization Form C, which
uses precomposed characters where available.  (This is the
normalization form recommended by the W3C and other bodies.)  This
holds when that code point is 0xffff or less, as it almost always is.

These will then be further transformed by the rules above into the
string @samp{_@var{xxxx}}, where @var{xxxx} is the code point in hex.

For example, combining this rule and the previous section:

@example
@@node @@b@{A@} @@TeX@{@} @@u@{B@} @@point@{@}@@enddots@{@}
@result{} A-TeX-B_0306-_2605_002e_002e_002e
@end example

Notice: 1)@tie{}@code{@@enddots} expands to three periods which in
turn expands to three @samp{_002e}'s; 2)@tie{}@code{@@u@{B@}} is a `B'
with a breve accent, which does not exist as a pre-accented Unicode
character, therefore expands to @samp{B_0306} (B with combining
breve).

When the Unicode code point is above 0xffff, the transformation is
@samp{__@var{xxxxxx}}, that is, two leading underscores followed by
six hex digits.  Since Unicode has declared that their highest code
point is 0x10ffff, this is sufficient.  (We felt it was better to
define this extra escape than to always use six hex digits, since the
first two would nearly always be zeros.)

This method works fine if the node name consists mostly of ASCII
characters and contains only few 8-bit ones. If the document is
written in a language whose script is not based on the Latin alphabet
(such as, e.g. Ukrainian), it will create file names consisting
entirely of @samp{_@var{xxxx}} notations, which is inconvenient.

To handle such cases, @command{makeinfo} offers
@option{--transliterate-file-names} command line option. This option
enables @dfn{transliteration} of node names into ASCII characters for
the purposes of file name creation and referencing. The
transliteration is based on phonetic principle, which makes the
produced file names easily readable.

For the definition of Unicode Normalization Form C, see Unicode report
UAX#15, @uref{http://www.unicode.org/reports/tr15/}.  Many related
documents and implementations are available elsewhere on the web.


@node HTML Xref Mismatch
@subsection HTML Cross-reference Mismatch
@cindex HTML cross-reference mismatch
@cindex Mismatched HTML cross-reference source and target

As mentioned earlier (@pxref{HTML Xref Link Basics}), the generating
software has to guess whether a given manual being cross-referenced is
available in split or monolithic form---and, inevitably, it might
guess wrong.  However, it is possible when the referent manual itself
is generated, it is possible to handle at least some mismatches.

In the case where we assume the referent is split, but it is actually
available in mono, the only recourse would be to generate a
@file{manual/} subdirectory full of HTML files which redirect back to
the monolithic @file{manual.html}.  Since this is essentially the same
as a split manual in the first place, it's not very appealing.

On the other hand, in the case where we assume the referent is mono,
but it is actually available in split, it is possible to use
JavaScript to redirect from the putatively monolithic
@file{manual.html} to the different @file{manual/node.html} files.
Here's an example:

@example
function redirect() @{
  switch (location.hash) @{
    case "#Node1":
      location.replace("manual/Node1.html#Node1"); break;
    case "#Node2" :
      location.replace("manual/Node2.html#Node2"); break;
    @dots{}
    default:;
  @}
@}
@end example

Then, in the @code{<body>} tag of @file{manual.html}:

@example
<body onLoad="redirect();">
@end example

Once again, this is something the software which generated the
@emph{referent} manual has to do in advance, it's not something the
software generating the actual cross-reference in the present manual
can control.

Ultimately, we hope to allow for an external configuration file to
control which manuals are available from where, and how.


@ignore
-- not yet --

external information
--------------------

The information for the reference is searched in the file
`htmlxref.cnf' present in the following directories:
<srcdir>/.texinfo/, ~/.texinfo/,  SYSCONFDIR/texinfo/,
DATADIR/texinfo/
The first match should be used.

The file is line-oriented, with the following format:
  <manualname> <whitespace> <keyword> <whitespace> <urlprefix>
with <keyword> being "mono" or "split". Thus
texinfo split http://www.gnu.org/software/texinfo/manual/texinfo/html_node/
texinfo mono http://www.gnu.org/software/texinfo/manual/texinfo/texinfo.html

If the keyword is 'split', that is the target is split, the urlprefix gives 
the directory and host name.
If the keyword is 'mono', that is the target is mono, the urlprefix gives 
directory, host and file name.

'#' followed by a space begins comments. '#' followed by another character
cannot begin comments as there are # in urls.

@end ignore


@node Command List
@appendix @@-Command List
@cindex Alphabetical @@-command list
@cindex List of  @@-commands
@cindex @@-command list
@cindex Reference to @@-commands

Here is an alphabetical list of the @@-commands in Texinfo.  Square
brackets, @t{[}@w{ }@t{]}, indicate optional arguments; an ellipsis,
@samp{@dots{}}, indicates repeated text.

More specifics on the general syntax of different @@-commands are
given in the section below.

@menu
* Command Syntax::    General syntax for varieties of @@-commands.
@end menu

@sp 1
@table @code
@item @@@var{whitespace}
An @code{@@} followed by a space, tab, or newline produces a normal,
stretchable, interword space.  @xref{Multiple Spaces}.

@item @@!
Produce an exclamation point that ends a sentence (usually after an
end-of-sentence capital letter).  @xref{Ending a Sentence}.

@item @@"
@itemx @@'
Generate an umlaut or acute accent, respectively, over the next
character, as in @"o and @'o.  @xref{Inserting Accents}.

@item @@*
Force a line break.  @xref{Line Breaks}.

@item @@,@{@var{c}@}
Generate a cedilla accent under @var{c}, as in @,{c}.  @xref{Inserting
Accents}.

@item @@-
Insert a discretionary hyphenation point.  @xref{- and hyphenation}.

@item @@.
Produce a period that ends a sentence (usually after an
end-of-sentence capital letter).  @xref{Ending a Sentence}.

@item @@/
Produces no output, but allows a line break.  @xref{Line Breaks}.

@item @@:
Tell @TeX{} to refrain from inserting extra whitespace after an
immediately preceding period, question mark, exclamation mark, or
colon, as @TeX{} normally would.  @xref{Not Ending a Sentence}.

@item @@=
Generate a macron (bar) accent over the next character, as in @=o.
@xref{Inserting Accents}.

@item @@?
Produce a question mark that ends a sentence (usually after an
end-of-sentence capital letter).  @xref{Ending a Sentence}.

@item @@@@
Stands for an at sign, @samp{@@}.
@xref{Atsign Braces Comma, , Inserting @@ and @{@} and @comma{}}.

@item @@\
Stands for a backslash (@samp{\}) inside @code{@@math}.
@xref{math,,@code{math}}.

@item @@^
@itemx @@`
Generate a circumflex (hat) or grave accent, respectively, over the next
character, as in @^o and @`e.
@xref{Inserting Accents}.

@item @@@{
Stands for a left brace, @samp{@{}.
@xref{Atsign Braces Comma, , Inserting @@ and @{@} and @comma{}}.

@item @@@}
Stands for a right-hand brace, @samp{@}}.@*
@xref{Atsign Braces Comma, , Inserting @@ and @{@} and @comma{}}.

@item @@~
Generate a tilde accent over the next character, as in @~N.
@xref{Inserting Accents}.

@item @@AA@{@}
@itemx @@aa@{@}
Generate the uppercase and lowercase Scandinavian A-ring letters,
respectively: @AA{}, @aa{}.  @xref{Inserting Accents}.

@item @@abbr@{@var{abbreviation}@}
Indicate a general abbreviation, such as `Comput.'.  @xref{abbr,,
@code{abbr}}.

@item @@acronym@{@var{acronym}@}
Indicate an acronym in all capital letters, such as `NASA'.
@xref{acronym,, @code{acronym}}.

@item @@AE@{@}
@itemx @@ae@{@}
Generate the uppercase and lowercase AE ligatures, respectively:
@AE{}, @ae{}.  @xref{Inserting Accents}.

@itemx @@afivepaper
Change page dimensions for the A5 paper size.  @xref{A4 Paper}.

@item @@afourlatex
@itemx @@afourpaper
@itemx @@afourwide
Change page dimensions for the A4 paper size.  @xref{A4 Paper}.

@item @@alias @var{new}=@var{existing}
Make the command @samp{@@@var{new}} a synonym for the existing command
@samp{@@@var{existing}}.  @xref{alias}.

@item @@anchor@{@var{name}@}
Define @var{name} as the current location for use as a cross-reference
target.  @xref{anchor,, @code{@@anchor}}.

@item @@appendix @var{title}
Begin an appendix.  The title appears in the table of contents.  In
Info, the title is underlined with asterisks.  @xref{unnumbered &
appendix, , The @code{@@unnumbered} and @code{@@appendix} Commands}.

@item @@appendixsec @var{title}
@itemx @@appendixsection @var{title}
Begin an appendix section within an appendix.  The section title
appears in the table of contents.  In Info, the title is underlined
with equal signs.  @code{@@appendixsection} is a longer spelling of
the @code{@@appendixsec} command.  @xref{unnumberedsec appendixsec
heading, , Section Commands}.

@item @@appendixsubsec @var{title}
Begin an appendix subsection.  The title appears in the table of
contents.  In Info, the title is underlined with hyphens.
@xref{unnumberedsubsec appendixsubsec subheading, , Subsection
Commands}.

@item @@appendixsubsubsec @var{title}
Begin an appendix subsubsection.  The title appears in the table of
contents.  In Info, the title is underlined with periods.
@xref{subsubsection,, The `subsub' Commands}.

@item @@arrow@{@}
Generate a right arrow glyph: @samp{@arrow{}}.  Used by default
for @code{@@click}.  @xref{Click Sequences}.

@item @@asis
Used following @code{@@table}, @code{@@ftable}, and @code{@@vtable} to
print the table's first column without highlighting (``as is'').
@xref{Two-column Tables}.

@item @@author @var{author}
Typeset @var{author} flushleft and underline it.  @xref{title
subtitle author, , The @code{@@title} and @code{@@author}
Commands}.@refill

@item @@b@{@var{text}@}
Set @var{text} in a @b{bold} font.  No effect in Info.  @xref{Fonts}.

@ignore
@item @@br
Force a paragraph break.  If used within a line, follow @code{@@br}
with braces.  @xref{br, , @code{@@br}}.@refill
@end ignore

@item @@bullet@{@}
Generate a large round dot, @bullet{} (@samp{*} in Info).  Often used
with @code{@@table}.  @xref{bullet, , @code{@@bullet}}.

@item @@bye
Stop formatting a file.  The formatters do not see anything in the 
input file following @code{@@bye}.  @xref{Ending a File}.

@item @@c @var{comment}
Begin a comment in Texinfo.  The rest of the line does not appear in
any output.  A synonym for
@code{@@comment}.  @xref{Comments}.

@item @@caption
Define the full caption for a @code{@@float}.  @xref{caption shortcaption}.

@item @@cartouche
Highlight an example or quotation by drawing a box with rounded
corners around it.  Pair with @code{@@end cartouche}.  No effect in
Info.  @xref{cartouche, , Drawing Cartouches Around Examples}.)@refill

@item @@center @var{line-of-text}
Center the line of text following the command.
@xref{titlefont center sp, , @code{@@center}}.@refill

@item @@centerchap @var{line-of-text}
Like @code{@@chapter}, but centers the chapter title.  @xref{chapter,,
@code{@@chapter}}.

@item @@chapheading @var{title}
Print an unnumbered chapter-like heading, but omit from the table of
contents.  In Info, the title is underlined with asterisks.
@xref{majorheading & chapheading, , @code{@@majorheading} and
@code{@@chapheading}}.

@item @@chapter @var{title}
Begin a numbered chapter.  The chapter title appears in the table of
contents.  In Info, the title is underlined with asterisks.
@xref{chapter, , @code{@@chapter}}.

@item @@cindex @var{entry}
Add @var{entry} to the index of concepts.  @xref{Index Entries, ,
Defining the Entries of an Index}.@refill

@item @@cite@{@var{reference}@}
Highlight the name of a book or other reference that has no companion
Info file.  @xref{cite, , @code{@@cite}}.

@item @@click@{@}
Represent a single ``click'' in a GUI.  Used within
@code{@@clicksequence}.  @xref{Click Sequences}.

@item @@clicksequence@{@var{action} @@click@{@} @var{action}@}
Represent a sequence of clicks in a GUI.  @xref{Click Sequences}.

@item @@clickstyle @@@var{cmd}
Execute @@@var{cmd} for each @code{@@click}; the default is
@code{@@arrow}.  The usual following empty braces on @@@var{cmd} are
omitted.  @xref{Click Sequences}.

@item @@clear @var{flag}
Unset @var{flag}, preventing the Texinfo formatting commands from
formatting text between subsequent pairs of @code{@@ifset @var{flag}}
and @code{@@end ifset} commands, and preventing
@code{@@value@{@var{flag}@}} from expanding to the value to which
@var{flag} is set.
@xref{set clear value, , @code{@@set} @code{@@clear} @code{@@value}}.@refill

@item @@code@{@var{sample-code}@}
Indicate an expression, a syntactically complete token of a program,
or a program name.  Unquoted in Info output.  @xref{code, ,
@code{@@code}}.

@item @@comma@{@}
Insert a comma `,' character; only needed when a literal comma would
be taken as an argument separator.  @xref{Inserting a Comma}.

@item @@command@{@var{command-name}@}
Indicate a command name, such as @command{ls}.
@xref{command,, @code{@@command}}.

@item @@comment @var{comment}
Begin a comment in Texinfo.  The rest of the line does not appear in
any output.  A synonym for @code{@@c}.
@xref{Comments}.

@item @@contents
Print a complete table of contents.  Has no effect in Info, which uses
menus instead.  @xref{Contents, , Generating a Table of
Contents}.@refill

@item @@copyright@{@}
Generate the copyright symbol @copyright{}.  @xref{copyright symbol,,
@code{@@copyright@{@}}}.

@ignore
@item @@ctrl@{@var{ctrl-char}@}
Describe an ASCII control character.  Insert actual control character
into Info file.  @xref{ctrl, , @code{@@ctrl}}.
@end ignore

@item @@defcodeindex @var{index-name}
Define a new index and its indexing command.  Print entries in an
@code{@@code} font.  @xref{New Indices, , Defining New Indices}.

@item @@defcv @var{category} @var{class} @var{name}
@itemx @@defcvx @var{category} @var{class} @var{name}
Format a description for a variable associated with a class in
object-oriented programming.  Takes three arguments: the category of
thing being defined, the class to which it belongs, and its name.
@xref{Definition Commands}, and @ref{deffnx,, Def Cmds in Detail}.

@item @@deffn @var{category} @var{name} @var{arguments}@dots{}
@itemx @@deffnx @var{category} @var{name} @var{arguments}@dots{}
Format a description for a function, interactive command, or similar
entity that may take arguments.  @code{@@deffn} takes as arguments the
category of entity being described, the name of this particular
entity, and its arguments, if any.  @xref{Definition Commands}.@refill

@item @@defindex @var{index-name}
Define a new index and its indexing command.  Print entries in a roman
font.  @xref{New Indices, , Defining New Indices}.@refill

@item @@definfoenclose @var{newcmd}, @var{before}, @var{after}
Must be used within @code{@@ifinfo}; create a new command
@code{@@@var{newcmd}} for Info that marks text by enclosing it in
strings that precede and follow the text.  @xref{definfoenclose}.

@item @@defivar @var{class} @var{instance-variable-name}
@itemx @@defivarx @var{class} @var{instance-variable-name}
Format a description for an instance variable in object-oriented
programming.  The command is equivalent to @samp{@@defcv @{Instance
Variable@} @dots{}}.  @xref{Definition Commands}, and @ref{deffnx,,
Def Cmds in Detail}.

@item @@defmac @var{macroname} @var{arguments}@dots{}
@itemx @@defmacx @var{macroname} @var{arguments}@dots{}
Format a description for a macro; equivalent to @samp{@@deffn Macro
@dots{}}.  @xref{Definition Commands}, and @ref{deffnx,, Def Cmds in
Detail}.

@item @@defmethod @var{class} @var{method-name} @var{arguments}@dots{}
@itemx @@defmethodx @var{class} @var{method-name} @var{arguments}@dots{}
Format a description for a method in object-oriented programming;
equivalent to @samp{@@defop Method @dots{}}.  @xref{Definition
Commands}, and @ref{deffnx,, Def Cmds in Detail}.

@item @@defop @var{category} @var{class} @var{name} @var{arguments}@dots{}
@itemx @@defopx @var{category} @var{class} @var{name} @var{arguments}@dots{}
Format a description for an operation in object-oriented programming.
@code{@@defop} takes as arguments the name of the category of
operation, the name of the operation's class, the name of the
operation, and its arguments, if any.  @xref{Definition Commands}, and
@ref{Abstract Objects}.

@item @@defopt @var{option-name}
@itemx @@defoptx @var{option-name}
Format a description for a user option; equivalent to @samp{@@defvr
@{User Option@} @dots{}}.  @xref{Definition Commands}, and
@ref{deffnx,, Def Cmds in Detail}.

@item @@defspec @var{special-form-name} @var{arguments}@dots{}
@itemx @@defspecx @var{special-form-name} @var{arguments}@dots{}
Format a description for a special form; equivalent to @samp{@@deffn
@{Special Form@} @dots{}}.  @xref{Definition Commands}, and
@ref{deffnx,, Def Cmds in Detail}.

@item @@deftp @var{category} @var{name-of-type} @var{attributes}@dots{}
@itemx @@deftpx @var{category} @var{name-of-type} @var{attributes}@dots{}
Format a description for a data type; its arguments are the category,
the name of the type (e.g., @samp{int}) , and then the names of
attributes of objects of that type.  @xref{Definition Commands}, and
@ref{Data Types}.

@item @@deftypecv @var{category} @var{class} @var{data-type} @var{name}
@itemx @@deftypecvx @var{category} @var{class} @var{data-type} @var{name}
Format a description for a typed class variable in object-oriented programming.
@xref{Definition Commands}, and @ref{Abstract Objects}.

@item @@deftypefn @var{category} @var{data-type} @var{name} @var{arguments}@dots{}
@itemx @@deftypefnx @var{category} @var{data-type} @var{name} @var{arguments}@dots{}
Format a description for a function or similar entity that may take
arguments and that is typed.  @code{@@deftypefn} takes as arguments the
category of entity being described, the type, the name of the
entity, and its arguments, if any.  @xref{Definition Commands}, and
@ref{deffnx,, Def Cmds in Detail}.

@item @@deftypefun @var{data-type} @var{function-name} @var{arguments}@dots{}
@itemx @@deftypefunx @var{data-type} @var{function-name} @var{arguments}@dots{}
Format a description for a function in a typed language.
The command is equivalent to @samp{@@deftypefn Function @dots{}}.
@xref{Definition Commands}, and @ref{deffnx,, Def Cmds in Detail}.

@item @@deftypeivar @var{class} @var{data-type} @var{variable-name}
@itemx @@deftypeivarx @var{class} @var{data-type} @var{variable-name}
Format a description for a typed instance variable in object-oriented
programming. @xref{Definition Commands}, and @ref{Abstract Objects}.

@item @@deftypemethod @var{class} @var{data-type} @var{method-name} @var{arguments}@dots{}
@itemx @@deftypemethodx @var{class} @var{data-type} @var{method-name} @var{arguments}@dots{}
Format a description for a typed method in object-oriented programming.
@xref{Definition Commands}, and @ref{deffnx,, Def Cmds in Detail}.

@item @@deftypeop @var{category} @var{class} @var{data-type} @var{name} @var{arguments}@dots{}
@itemx @@deftypeopx @var{category} @var{class} @var{data-type} @var{name} @var{arguments}@dots{}
Format a description for a typed operation in object-oriented programming.
@xref{Definition Commands}, and @ref{Abstract Objects}.

@item @@deftypevar @var{data-type} @var{variable-name}
@itemx @@deftypevarx @var{data-type} @var{variable-name}
Format a description for a variable in a typed language.  The command is
equivalent to @samp{@@deftypevr Variable @dots{}}.  @xref{Definition
Commands}, and @ref{deffnx,, Def Cmds in Detail}.

@item @@deftypevr @var{category} @var{data-type} @var{name}
@itemx @@deftypevrx @var{category} @var{data-type} @var{name}
Format a description for something like a variable in a typed
language---an entity that records a value.  Takes as arguments the
category of entity being described, the type, and the name of the
entity.  @xref{Definition Commands}, and @ref{deffnx,, Def Cmds in
Detail}.

@item @@defun @var{function-name} @var{arguments}@dots{}
@itemx @@defunx @var{function-name} @var{arguments}@dots{}
Format a description for a function; equivalent to
@samp{@@deffn Function @dots{}}.  @xref{Definition Commands}, and
@ref{deffnx,, Def Cmds in Detail}.

@item @@defvar @var{variable-name}
@itemx @@defvarx @var{variable-name}
Format a description for a variable; equivalent to @samp{@@defvr
Variable @dots{}}.  @xref{Definition Commands}, and @ref{deffnx,, Def
Cmds in Detail}.

@item @@defvr @var{category} @var{name}
@itemx @@defvrx @var{category} @var{name}
Format a description for any kind of variable.  @code{@@defvr} takes
as arguments the category of the entity and the name of the entity.
@xref{Definition Commands},
and @ref{deffnx,, Def Cmds in Detail}.

@item @@detailmenu
Mark the (optional) detailed node listing in a master menu.
@xref{Master Menu Parts}.

@item @@dfn@{@var{term}@}
Indicate the introductory or defining use of a term.  @xref{dfn, ,
@code{@@dfn}}.

@item @@dircategory @var{dirpart}
Specify a part of the Info directory menu where this file's entry should
go.  @xref{Installing Dir Entries}.

@item @@direntry
Begin the Info directory menu entry for this file.  Pair with
@code{@@end direntry}.  @xref{Installing Dir Entries}.

@item @@display
Begin a kind of example.  Like @code{@@example} (indent text, do not
fill), but do not select a new font.  Pair with @code{@@end display}.
@xref{display, , @code{@@display}}.

@item @@dmn@{@var{dimension}@}
Format a unit of measure, as in 12@dmn{pt}.  Causes @TeX{} to insert a
thin space before @var{dimension}.  No effect in Info.
@xref{dmn, , @code{@@dmn}}.

@item @@docbook
Enter Docbook completely.  Pair with @code{@@end docbook}.  @xref{Raw
Formatter Commands}.

@item @@documentdescription
Set the document description text, included in the HTML output.  Pair
with @code{@@end documentdescription}.  @xref{documentdescription,,
@code{@@documentdescription}}.

@item @@documentencoding @var{enc}
Declare the input encoding to be @var{enc}.
@xref{documentencoding,, @code{@@documentencoding}}.

@item @@documentlanguage @var{CC}
Declare the document language as the two-character ISO-639 abbreviation
@var{CC}.  @xref{documentlanguage,, @code{@@documentlanguage}}.

@item @@dotaccent@{@var{c}@}
Generate a dot accent over the character @var{c}, as in @dotaccent{o}.
@xref{Inserting Accents}.

@item @@dots@{@}
Generate an ellipsis, @samp{@dots{}}.
@xref{dots, , @code{@@dots}}.@refill

@item @@email@{@var{address}[, @var{displayed-text}]@}
Indicate an electronic mail address.
@xref{email, , @code{@@email}}.

@item @@emph@{@var{text}@}
Emphasize @var{text}, by using @emph{italics} where possible, and
enclosing in asterisks in Info.  @xref{Emphasis, , Emphasizing Text}.

@item @@end @var{environment}
Ends @var{environment}, as in @samp{@@end example}.  @xref{Formatting
Commands,,@@-commands}.

@item @@env@{@var{environment-variable}@}
Indicate an environment variable name, such as @env{PATH}.
@xref{env,, @code{@@env}}.

@item @@enddots@{@}
Generate an end-of-sentence ellipsis, like this: @enddots{}
@xref{dots,,@code{@@dots@{@}}}.

@item @@enumerate [@var{number-or-letter}]
Begin a numbered list, using @code{@@item} for each entry.
Optionally, start list with @var{number-or-letter}.  Pair with
@code{@@end enumerate}.  @xref{enumerate, ,
@code{@@enumerate}}.@refill

@item @@equiv@{@}
Indicate to the reader the exact equivalence of two forms with a
glyph: @samp{@equiv{}}.  @xref{Equivalence}.@refill

@item @@euro@{@}
Generate the Euro currency sign.
@xref{euro,,@code{@@euro@{@}}}.

@item @@error@{@}
Indicate to the reader with a glyph that the following text is
an error message: @samp{@error{}}.  @xref{Error Glyph}.@refill

@item  @@evenfooting [@var{left}] @@| [@var{center}] @@| [@var{right}]
@itemx @@evenheading [@var{left}] @@| [@var{center}] @@| [@var{right}]
Specify page footings resp.@: headings for even-numbered (left-hand)
pages.  @xref{Custom Headings, ,
How to Make Your Own Headings}.@refill

@item @@everyfooting [@var{left}] @@| [@var{center}] @@| [@var{right}]
@itemx @@everyheading [@var{left}] @@| [@var{center}] @@| [@var{right}]
Specify page footings resp.@: headings for every page.  Not relevant to
Info.  @xref{Custom Headings, , How to Make Your Own Headings}.

@item @@example
Begin an example.  Indent text, do not fill, and select fixed-width
font.  Pair with @code{@@end example}.  @xref{example,, @code{@@example}}.

@item @@exampleindent @var{indent}
Indent example-like environments by @var{indent} number of spaces
(perhaps 0).  @xref{exampleindent,, Paragraph Indenting}.

@item @@exclamdown@{@}
Generate an upside-down exclamation point.  @xref{Inserting Accents}.

@item @@exdent @var{line-of-text}
Remove any indentation a line might have.  @xref{exdent, ,
Undoing the Indentation of a Line}.@refill

@item @@expansion@{@}
Indicate the result of a macro expansion to the reader with a special
glyph: @samp{@expansion{}}.
@xref{expansion, , @expansion{} Indicating an Expansion}.@refill

@item @@file@{@var{filename}@}
Highlight the name of a file, buffer, node, directory, etc.  @xref{file, ,
@code{@@file}}.

@item @@finalout
Prevent @TeX{} from printing large black warning rectangles beside
over-wide lines.  @xref{Overfull hboxes}.@refill

@item @@findex @var{entry}
Add @var{entry} to the index of functions.  @xref{Index Entries, ,
Defining the Entries of an Index}.@refill

@item @@float
Environment to define floating material.  Pair with @code{@@end float}.
@xref{Floats}.

@item @@flushleft
@itemx @@flushright
Do not fill text; left (right) justify every line while leaving the
right (left) end ragged.  Leave font as is.  Pair with @code{@@end
flushleft} (@code{@@end flushright}).  @code{@@flushright} analogous.
@xref{flushleft & flushright, , @code{@@flushleft} and
@code{@@flushright}}.

@item @@footnote@{@var{text-of-footnote}@}
Enter a footnote.  Footnote text is printed at the bottom of the page
by @TeX{}; Info may format in either `End' node or `Separate' node style.
@xref{Footnotes}.

@item @@footnotestyle @var{style}
Specify an Info file's footnote style, either @samp{end} for the end
node style or @samp{separate} for the separate node style.
@xref{Footnotes}.

@item @@format
Begin a kind of example.  Like @code{@@display}, but do not indent.
Pair with @code{@@end format}.  @xref{example,, @code{@@example}}.

@item @@ftable @var{formatting-command}
Begin a two-column table, using @code{@@item} for each entry.
Automatically enter each of the items in the first column into the
index of functions.  Pair with @code{@@end ftable}.  The same as
@code{@@table}, except for indexing.  @xref{ftable vtable, ,
@code{@@ftable} and @code{@@vtable}}.@refill

@item @@geq@{@}
Generate a greater-than-or-equal sign, `@geq{}'.  @xref{geq leq}.

@item @@group
Disallow page breaks within following text.  Pair with @code{@@end
group}.  Ignored in Info.  @xref{group, , @code{@@group}}.

@item @@H@{@var{c}@}
Generate the long Hungarian umlaut accent over @var{c}, as in @H{o}.

@item @@heading @var{title}
Print an unnumbered section-like heading, but omit from the table of
contents.  In Info, the title is underlined with equal signs.
@xref{unnumberedsec appendixsec heading, , Section Commands}.

@item @@headings @var{on-off-single-double}
Turn page headings on or off, and/or specify single-sided or double-sided
page headings for printing.  @xref{headings on off, , The
@code{@@headings} Command}.

@item @@headitem
Begin a heading row in a multitable.  @xref{Multitable Rows}.

@item @@html
Enter HTML completely.  Pair with @code{@@end html}.  @xref{Raw
Formatter Commands}.

@item @@hyphenation@{@var{hy-phen-a-ted words}@}
Explicitly define hyphenation points.  @xref{- and hyphenation,,
@code{@@-} and @code{@@hyphenation}}.

@item @@i@{@var{text}@}
Set @var{text} in an @i{italic} font.  No effect in Info.  @xref{Fonts}.

@item @@ifclear @var{txivar}
If the Texinfo variable @var{txivar} is not set, format the following
text.  Pair with @code{@@end ifclear}.  @xref{set clear value, ,
@code{@@set} @code{@@clear} @code{@@value}}.

@item @@ifdocbook
@itemx @@ifhtml
@itemx @@ifinfo
Begin text that will appear only in the given output format.
@code{@@ifinfo} output appears in both Info and (for historical
compatibility) plain text output.  Pair with @code{@@end ifdocbook}
resp.@: @code{@@end ifhtml} resp.@: @code{@@end ifinfo}.
@xref{Conditionals}.

@item @@ifnotdocbook
@itemx @@ifnothtml
@itemx @@ifnotplaintext
@itemx @@ifnottex
@itemx @@ifnotxml
Begin text to be ignored in one output format but not the others.
@code{@@ifnothtml} text is omitted from HTML output, etc.  Pair with
the corresponding @code{@@end ifnot@var{format}}.
@xref{Conditionals}.

@itemx @@ifnotinfo
Begin text to appear in output other than Info and (for historical
compatibility) plain text.  Pair with @code{@@end ifnotinfo}.
@xref{Conditionals}.

@item @@ifplaintext
Begin text that will appear only in the plain text output.
Pair with @code{@@end ifplaintext}.  @xref{Conditionals}.

@item @@ifset @var{txivar}
If the Texinfo variable @var{txivar} is set, format the following
text.  Pair with @code{@@end ifset}.  @xref{set clear value, ,
@code{@@set} @code{@@clear} @code{@@value}}.

@item @@iftex
Begin text to appear only in the @TeX{} output.  Pair with @code{@@end
iftex}.  @xref{Conditionals, , Conditionally Visible Text}.@refill

@item @@ifxml
Begin text that will appear only in the XML output.  Pair with
@code{@@end ifxml}.  @xref{Conditionals}.

@item @@ignore
Begin text that will not appear in any output.  Pair with @code{@@end
ignore}.  @xref{Comments, , Comments and Ignored Text}.

@item @@image@{@var{filename}, [@var{width}], [@var{height}], [@var{alt}], [@var{ext}]@}
Include graphics image in external @var{filename} scaled to the given
@var{width} and/or @var{height}, using @var{alt} text and looking for
@samp{@var{filename}.@var{ext}} in HTML.  @xref{Images}.

@item @@include @var{filename}
Read the contents of Texinfo source file @var{filename}.  @xref{Include Files}.

@item @@indicateurl@{@var{indicateurl}@}
Indicate text that is a uniform resource locator for the World Wide
Web.  @xref{indicateurl, , @code{@@indicateurl}}.

@item @@inforef@{@var{node-name}, [@var{entry-name}], @var{info-file-name}@}
Make a cross reference to an Info file for which there is no printed
manual.  @xref{inforef, , Cross references using
@code{@@inforef}}.@refill

@item \input @var{macro-definitions-file}
Use the specified macro definitions file.  This command is used only
in the first line of a Texinfo file to cause @TeX{} to make use of the
@file{texinfo} macro definitions file.  The backslash in @code{\input}
is used instead of an @code{@@} because @TeX{} does not
recognize @code{@@} until after it has read the definitions file.
@xref{Texinfo File Header}.

@item @@item
Indicate the beginning of a marked paragraph for @code{@@itemize} and
@code{@@enumerate}; indicate the beginning of the text of a first column
entry for @code{@@table}, @code{@@ftable}, and @code{@@vtable}.
@xref{Lists and Tables}.

@item @@itemize @var{mark-generating-character-or-command}
Begin an unordered list: indented paragraphs with a mark, such as
@code{@@bullet}, inside the left margin at the beginning of each
item.  Pair with @code{@@end itemize}.  @xref{itemize, ,
@code{@@itemize}}.

@item @@itemx
Like @code{@@item} but do not generate extra vertical space above the
item text.  Thus, when several items have the same description, use
@code{@@item} for the first and @code{@@itemx} for the others.
@xref{itemx, , @code{@@itemx}}.

@item @@kbd@{@var{keyboard-characters}@}
Indicate characters of input to be typed by users.  @xref{kbd, ,
@code{@@kbd}}.

@item @@kbdinputstyle @var{style}
Specify when @code{@@kbd} should use a font distinct from
@code{@@code}.  @xref{kbd, , @code{@@kbd}}.

@item @@key@{@var{key-name}@}
Indicate the name of a key on a keyboard.  @xref{key, , @code{@@key}}.

@item @@kindex @var{entry}
Add @var{entry} to the index of keys.
@xref{Index Entries, , Defining the Entries of an Index}.@refill

@item @@L@{@}
@itemx @@l@{@}
Generate the uppercase and lowercase Polish suppressed-L letters,
respectively: @L{}, @l{}.

@item @@LaTeX@{@}
Generate the @LaTeX{} logo.  @xref{tex, , @TeX{} and @LaTeX{}}.

@item @@leq@{@}
Generate a less-than-or-equal sign, `@leq{}'.  @xref{geq leq}.

@item @@lisp
Begin an example of Lisp code.  Indent text, do not fill, and select
fixed-width font.  Pair with @code{@@end lisp}.  @xref{lisp, , @code{@@lisp}}.

@item @@listoffloats
Produce a table-of-contents-like listing of @code{@@float}s.
@xref{listoffloats}.

@item @@lowersections
Change subsequent chapters to sections, sections to subsections, and so
on. @xref{Raise/lower sections, , @code{@@raisesections} and
@code{@@lowersections}}.@refill

@item @@macro @var{macroname} @{@var{params}@}
Define a new Texinfo command @code{@@@var{macroname}@{@var{params}@}}.
Pair with @code{@@end macro}.  @xref{Defining Macros}.

@item @@majorheading @var{title}
Print an unnumbered chapter-like heading, but omit from
the table of contents.  This generates more vertical whitespace before
the heading than the @code{@@chapheading} command.  @xref{majorheading
& chapheading, , @code{@@majorheading} and @code{@@chapheading}}.

@item @@math@{@var{mathematical-expression}@}
Format a mathematical expression.
@xref{math, , @code{@@math}: Inserting Mathematical Expressions}.

@item @@menu
Mark the beginning of a menu of nodes.  No effect in a printed manual.
Pair with @code{@@end menu}.  @xref{Menus}.

@item @@minus@{@}
Generate a minus sign, `@minus{}'.  @xref{minus, , @code{@@minus}}.

@item @@multitable @var{column-width-spec}
Begin a multi-column table.  Begin each row with @code{@@item} or
@code{@@headitem}, and separate columns with @code{@@tab}.  Pair with
@code{@@end multitable}.  @xref{Multitable Column Widths}.

@item @@need @var{n}
Start a new page in a printed manual if fewer than @var{n} mils
(thousandths of an inch) remain on the current page.  @xref{need, ,
@code{@@need}}.

@item @@node @var{name}, @var{next}, @var{previous}, @var{up}
Begin a new node.  @xref{node, , @code{@@node}}.

@item @@noindent
Prevent text from being indented as if it were a new paragraph.
@xref{noindent, , @code{@@noindent}}.

@item @@novalidate
Suppress validation of node references and omit creation of auxiliary
files with @TeX{}.  Use before @code{@@setfilename}.  @xref{Pointer
Validation}.

@item @@O@{@}
@itemx @@o@{@}
Generate the uppercase and lowercase O-with-slash letters, respectively:
@O{}, @o{}.

@item  @@oddfooting [@var{left}] @@| [@var{center}] @@| [@var{right}]
@itemx @@oddheading [@var{left}] @@| [@var{center}] @@| [@var{right}]
Specify page footings resp.@: headings for odd-numbered (right-hand)
pages.  @xref{Custom Headings, ,
How to Make Your Own Headings}.@refill

@item @@OE@{@}
@itemx @@oe@{@}
Generate the uppercase and lowercase OE ligatures, respectively:
@OE{}, @oe{}.  @xref{Inserting Accents}.

@item @@option@{@var{option-name}@}
Indicate a command-line option, such as @option{-l} or @option{--help}.
@xref{option,, @code{@@option}}.

@item @@page
Start a new page in a printed manual.  No effect in Info.
@xref{page, , @code{@@page}}.@refill

@item @@pagesizes [@var{width}][, @var{height}]
Change page dimensions.  @xref{pagesizes}.

@item @@paragraphindent @var{indent}
Indent paragraphs by @var{indent} number of spaces (perhaps 0); preserve
source file indentation if @var{indent} is @code{asis}.
@xref{paragraphindent,, Paragraph Indenting}.

@item @@pindex @var{entry}
Add @var{entry} to the index of programs.  @xref{Index Entries, , Defining
the Entries of an Index}.@refill

@item @@point@{@}
Indicate the position of point in a buffer to the reader with a
glyph: @samp{@point{}}.  @xref{Point Glyph, , Indicating
Point in a Buffer}.@refill

@item @@pounds@{@}
Generate the pounds sterling currency sign.
@xref{pounds,,@code{@@pounds@{@}}}.

@item @@print@{@}
Indicate printed output to the reader with a glyph:
@samp{@print{}}.  @xref{Print Glyph}.@refill

@item @@printindex @var{index-name}
Generate the alphabetized index for @var{index-name} (using two columns in a printed
manual).  @xref{Printing Indices & Menus}.

@item @@pxref@{@var{node}, [@var{entry}], [@var{node-title}], [@var{info-file}], [@var{manual}]@}
Make a reference that starts with a lower case `see' in a printed
manual.  Use within parentheses only.  Only the first argument is
mandatory.  @xref{pxref, , @code{@@pxref}}.

@item @@questiondown@{@}
Generate an upside-down question mark.  @xref{Inserting Accents}.

@item @@quotation
Narrow the margins to indicate text that is quoted from another work.
Takes optional argument of prefix text.  Pair with @code{@@end
quotation}.  @xref{quotation, , @code{@@quotation}}.

@item @@r@{@var{text}@}
Set @var{text} in the regular @r{roman} font.  No effect in Info.
@xref{Fonts}.

@item @@raisesections
Change subsequent sections to chapters, subsections to sections, and so
on.  @xref{Raise/lower sections, , @code{@@raisesections} and
@code{@@lowersections}}.@refill

@item @@ref@{@var{node}, [@var{entry}], [@var{node-title}], [@var{info-file}], [@var{manual}]@}
Make a plain reference that does not start with any special text.
Follow command with a punctuation mark.  Only the first argument is
mandatory.  @xref{ref, , @code{@@ref}}.

@item @@refill
This command used to refill and indent the paragraph after all the
other processing has been done.  It is no longer needed, since all
formatters now automatically refill as needed, but you may still see
it in the source to some manuals, as it does no harm.

@item @@registeredsymbol@{@}
Generate the legal symbol @registeredsymbol{}.  @xref{registered
symbol,, @code{@@registeredsymbol@{@}}}.

@item @@result@{@}
Indicate the result of an expression to the reader with a special
glyph: @samp{@result{}}.  @xref{result, , @code{@@result}}.@refill

@item @@ringaccent@{@var{c}@}
Generate a ring accent over the next character, as in @ringaccent{o}.
@xref{Inserting Accents}.

@item @@samp@{@var{text}@}
Indicate a literal example of a sequence of characters, in general.
Quoted in Info output.  @xref{samp, , @code{@@samp}}.

@item @@sansserif@{@var{text}@}
Set @var{text} in a @sansserif{sans serif} font if possible.  No
effect in Info.  @xref{Fonts}.

@item @@sc@{@var{text}@}
Set @var{text} in a small caps font in printed output, and uppercase
in Info.  @xref{Smallcaps}.

@item @@section @var{title}
Begin a section within a chapter.  The section title appears in the
table of contents.  In Info, the title is underlined with equal signs.
Within @code{@@chapter} and @code{@@appendix}, the section title is
numbered; within @code{@@unnumbered}, the section is unnumbered.
@xref{section, , @code{@@section}}.

@item @@set @var{txivar} [@var{string}]
Define the Texinfo variable @var{txivar}, optionally to the value
@var{string}.  @xref{set clear value, , @code{@@set} @code{@@clear}
@code{@@value}}.

@item @@setchapternewpage @var{on-off-odd}
Specify whether chapters start on new pages, and if so, whether on
odd-numbered (right-hand) new pages.  @xref{setchapternewpage, ,
@code{@@setchapternewpage}}.

@item @@setcontentsaftertitlepage
Put the table of contents after the @samp{@@end titlepage} even if the
@code{@@contents} command is at the end.  @xref{Contents}.

@item @@setfilename @var{info-file-name}
Provide a name to be used for the output files.  This command is essential
for @TeX{} formatting as well, even though it produces no output of
its own.  @xref{setfilename, , @code{@@setfilename}}.

@item @@setshortcontentsaftertitlepage
Place the short table of contents after the @samp{@@end titlepage}
command even if the @code{@@shortcontents} command is at the end.
@xref{Contents}.

@item @@settitle @var{title}
Specify the title for page headers in a printed manual, and the
default document description for HTML @samp{<head>}.  @xref{settitle,,
@code{@@settitle}}.

@item @@shortcaption
Define the short caption for a @code{@@float}.  @xref{caption shortcaption}.

@item @@shortcontents
Print a short table of contents, with chapter-level entries only.  Not
relevant to Info, which uses menus rather than tables of contents.
@xref{Contents, , Generating a Table of Contents}.

@item @@shorttitlepage @var{title}
Generate a minimal title page.  @xref{titlepage,,@code{@@titlepage}}.

@item @@slanted@{@var{text}@}
Set @var{text} in a @slanted{slanted} font if possible.  No effect
in Info.  @xref{Fonts}.

@item @@smallbook
Cause @TeX{} to produce a printed manual in a 7 by 9.25 inch format
rather than the regular 8.5 by 11 inch format.  @xref{smallbook, ,
Printing Small Books}.  Also, see @ref{small}.

@item @@smalldisplay
Begin a kind of example.  Like @code{@@smallexample} (narrow margins, no
filling), but do not select the fixed-width font.  Pair with @code{@@end
smalldisplay}.  @xref{small}.

@item @@smallexample
Begin an example.  Do not fill, select fixed-width font, narrow the
margins.  Where possible, print text in a smaller font than with
@code{@@example}.  Pair with @code{@@end smallexample}.  @xref{small}.

@item @@smallformat
Begin a kind of example.  Like @code{@@smalldisplay}, but do not narrow
the margins.  Pair with @code{@@end smallformat}.  @xref{small}.

@item @@smalllisp
Begin an example of Lisp code.  Same as @code{@@smallexample}.  Pair
with @code{@@end smalllisp}.  @xref{small}.

@item @@sp @var{n}
Skip @var{n} blank lines.  @xref{sp, , @code{@@sp}}.@refill

@item @@ss@{@}
Generate the German sharp-S es-zet letter, @ss{}.  @xref{Inserting Accents}.

@item @@strong @{@var{text}@}
Emphasize @var{text} more strongly than @code{@@emph}, by using
@strong{boldface} where possible; enclosed in asterisks in Info.
@xref{emph & strong, , Emphasizing Text}.

@item @@subheading @var{title}
Print an unnumbered subsection-like heading, but omit from the table
of contents of a printed manual.  In Info, the title is underlined
with hyphens.  @xref{unnumberedsubsec appendixsubsec subheading, ,
@code{@@unnumberedsubsec} @code{@@appendixsubsec}
@code{@@subheading}}.

@item @@subsection @var{title}
Begin a subsection within a section.  The subsection title appears in
the table of contents.  In Info, the title is underlined with hyphens.
Same context-dependent numbering as @code{@@section}.  @xref{subsection, ,
@code{@@subsection}}.

@item @@subsubheading @var{title}
Print an unnumbered subsubsection-like heading, but omit from the
table of contents of a printed manual.  In Info, the title is
underlined with periods.  @xref{subsubsection, , The `subsub'
Commands}.

@item @@subsubsection @var{title}
Begin a subsubsection within a subsection.  The subsubsection title
appears in the table of contents.  In Info, the title is underlined
with periods.  Same context-dependent numbering as @code{@@section}.
@xref{subsubsection, , The `subsub' Commands}.

@item @@subtitle @var{title}
In a printed manual, set a subtitle in a normal sized font flush to
the right-hand side of the page.  Not relevant to Info, which does not
have title pages.  @xref{title subtitle author, , @code{@@title}
@code{@@subtitle} and @code{@@author} Commands}.

@item @@summarycontents
Print a short table of contents.  Synonym for @code{@@shortcontents}.
@xref{Contents, , Generating a Table of Contents}.

@item @@syncodeindex @var{from-index} @var{to-index}
Merge the index named in the first argument into the index named in
the second argument, formatting the entries from the first index with
@code{@@code} .  @xref{Combining Indices}.@refill

@item @@synindex @var{from-index} @var{to-index}
Merge the index named in the first argument into the index named in
the second argument.  Do not change the font of @var{from-index}
entries.  @xref{Combining Indices}.

@item @@t@{@var{text}@}
Set @var{text} in a @t{fixed-width}, typewriter-like font.  No effect
in Info.  @xref{Fonts}.

@item @@tab
Separate columns in a row of a multitable.  @xref{Multitable Rows}.

@item @@table @var{formatting-command}
Begin a two-column table (description list), using @code{@@item} for
each entry.  Write each first column entry on the same line as
@code{@@item}.  First column entries are printed in the font resulting
from @var{formatting-command}.  Pair with @code{@@end table}.
@xref{Two-column Tables, , Making a Two-column Table}.  Also see
@ref{ftable vtable, , @code{@@ftable} and @code{@@vtable}}, and
@ref{itemx, , @code{@@itemx}}.

@item @@TeX@{@}
Generate the @TeX{} logo.  @xref{tex, , @TeX{} and @LaTeX{}}.

@item @@tex
Enter @TeX{} completely.  Pair with @code{@@end tex}.  @xref{Raw
Formatter Commands}.

@item @@thischapter
@itemx @@thischaptername
@itemx @@thischapternum
@itemx @@thisfile
@itemx @@thispage
@itemx @@thistitle
Only allowed in a heading or footing.  Stands for, respectively, the
number and name of the current chapter (in the format `Chapter 1:
Title'), the current chapter name only, the current chapter number
only, the filename, the current page number, and the title of the
document, respectively.  @xref{Custom Headings, , How to Make Your Own
Headings}.

@item @@tie@{@}
Generate a normal interword space at which a line break is not allowed.
@xref{tie,, @code{@@tie@{@}}}.

@item @@tieaccent@{@var{cc}@}
Generate a tie-after accent over the next two characters @var{cc}, as in
`@tieaccent{oo}'.  @xref{Inserting Accents}.

@item @@tindex @var{entry}
Add @var{entry} to the index of data types.  @xref{Index Entries, ,
Defining the Entries of an Index}.@refill

@item @@title @var{title}
In a printed manual, set a title flush to the left-hand side of the
page in a larger than normal font and underline it with a black rule.
Not relevant to Info, which does not have title pages.  @xref{title
subtitle author, , The @code{@@title} @code{@@subtitle} and
@code{@@author} Commands}.@refill

@item @@titlefont@{@var{text}@}
In a printed manual, print @var{text} in a larger than normal font.
@xref{titlefont center sp, , The @code{@@titlefont} @code{@@center}
and @code{@@sp} Commands}.

@item @@titlepage
Begin the title page.  Write the command on a line of its own, paired
with @code{@@end titlepage}.  Nothing between @code{@@titlepage} and
@code{@@end titlepage} appears in Info.  @xref{titlepage, ,
@code{@@titlepage}}.@refill

@item @@today@{@}
Insert the current date, in `1 Jan 1900' style.  @xref{Custom
Headings, , How to Make Your Own Headings}.@refill

@item @@top @var{title}
Mark the topmost @code{@@node} in the file, which must be defined on
the line immediately preceding the @code{@@top} command.  The title is
formatted as a chapter-level heading.  The entire top node, including
the @code{@@node} and @code{@@top} lines, are normally enclosed with
@code{@@ifnottex ... @@end ifnottex}.  In @TeX{} and
@code{texinfo-format-buffer}, the @code{@@top} command is merely a
synonym for @code{@@unnumbered}.  @xref{makeinfo Pointer Creation, ,
Creating Pointers with @code{makeinfo}}.

@item @@u@{@var{c}@}
@itemx @@ubaraccent@{@var{c}@}
@itemx @@udotaccent@{@var{c}@}
Generate a breve, underbar, or underdot accent, respectively, over or
under the character @var{c}, as in @u{o}, @ubaraccent{o},
@udotaccent{o}.  @xref{Inserting Accents}.

@item @@unnumbered @var{title}
Begin a chapter that appears without chapter numbers of any kind.  The
title appears in the table of contents.  In Info, the title is
underlined with asterisks.  @xref{unnumbered & appendix, ,
@code{@@unnumbered} and @code{@@appendix}}.

@item @@unnumberedsec @var{title}
Begin a section that appears without section numbers of any kind.  The
title appears in the table of contents of a printed manual.  In Info,
the title is underlined with equal signs.  @xref{unnumberedsec
appendixsec heading, , Section Commands}.

@item @@unnumberedsubsec @var{title}
Begin an unnumbered subsection.  The title appears in the table of
contents.  In Info, the title is underlined with hyphens.
@xref{unnumberedsubsec appendixsubsec subheading, ,
@code{@@unnumberedsubsec} @code{@@appendixsubsec}
@code{@@subheading}}.

@item @@unnumberedsubsubsec @var{title}
Begin an unnumbered subsubsection.  The title appears in the table of
contents.  In Info, the title is underlined with periods.
@xref{subsubsection, , The `subsub' Commands}.

@item @@uref@{@var{url}[, @var{displayed-text}][, @var{replacement}@}
@itemx @@url@{@var{url}[, @var{displayed-text}][, @var{replacement}@}
Define a cross reference to an external uniform resource locator,
e.g., for the World Wide Web.  @xref{uref, , @code{@@uref}}.

@item @@v@{@var{c}@}
Generate check accent over the character @var{c}, as in @v{o}.
@xref{Inserting Accents}.

@item @@value@{@var{txivar}@}
Insert the value, if any, of the Texinfo variable @var{txivar},
previously defined by @code{@@set}.  @xref{set clear value, ,
@code{@@set} @code{@@clear} @code{@@value}}.

@item @@var@{@var{metasyntactic-variable}@}
Highlight a metasyntactic variable, which is something that stands for
another piece of text.  @xref{var, , Indicating Metasyntactic
Variables}.

@item @@verb@{@var{delim} @var{literal} @var{delim}@}
Output @var{literal}, delimited by the single character @var{delim},
exactly as is (in the fixed-width font), including any whitespace or
Texinfo special characters.  @xref{verb,,@code{verb}}.

@item @@verbatim
Output the text of the environment exactly as is (in the fixed-width
font).  Pair with @code{@@end verbatim}.  @xref{verbatim,,@code{verbatim}}.

@item @@verbatiminclude @var{filename}
Output the contents of @var{filename} exactly as is (in the fixed-width font).
@xref{verbatiminclude,,@code{verbatiminclude}}.

@item @@vindex @var{entry}
Add @var{entry} to the index of variables.  @xref{Index Entries, ,
Defining the Entries of an Index}.@refill

@item @@vskip @var{amount}
In a printed manual, insert whitespace so as to push text on the
remainder of the page towards the bottom of the page.  Used in
formatting the copyright page with the argument @samp{0pt plus
1filll}.  (Note spelling of @samp{filll}.)  @code{@@vskip} may be used
only in contexts ignored for Info.  @xref{Copyright}.

@item @@vtable @var{formatting-command}
Begin a two-column table, using @code{@@item} for each entry.
Automatically enter each of the items in the first column into the
index of variables.  Pair with @code{@@end vtable}.  The same as
@code{@@table}, except for indexing.  @xref{ftable vtable, ,
@code{@@ftable} and @code{@@vtable}}.@refill

@item @@w@{@var{text}@}
Disallow line breaks within @var{text}.  @xref{w, , @code{@@w}}.

@item @@xml
Enter XML completely.  Pair with @code{@@end xml}.  @xref{Raw
Formatter Commands}.

@item @@xref@{@var{node}, [@var{entry}], [@var{node-title}], [@var{info-file}], [@var{manual}]@}
Make a reference that starts with `See' in a printed manual.  Follow
command with a punctuation mark.  Only the first argument is
mandatory.  @xref{xref, , @code{@@xref}}.

@end table


@node Command Syntax
@section @@-Command Syntax
@cindex @@-command syntax
@cindex Syntax, of @@-commands
@cindex Command syntax

The character @samp{@@} is used to start special Texinfo commands.
(It has the same meaning that @samp{\} has in plain @TeX{}.)  Texinfo
has four types of @@-command:@refill

@table @asis
@item 1. Non-alphabetic commands.
These commands consist of an @@ followed by a punctuation mark or
other character that is not part of the alphabet.  Non-alphabetic
commands are almost always part of the text within a paragraph.  The
non-alphabetic commands include @code{@@@@}, @code{@@@{}, @code{@@@}},
@code{@@.}, @code{@@@kbd{SPACE}}, most of the accent commands, and
many more.

@item 2. Alphabetic commands that do not require arguments.
These commands start with @@ followed by a word followed by left- and
right-hand braces.  These commands insert special symbols in the
document; they do not require arguments.  For example,
@code{@@dots@{@}} @result{} @samp{@dots{}}, @code{@@equiv@{@}}
@result{} @samp{@equiv{}}, @code{@@TeX@{@}} @result{} `@TeX{}',
and @code{@@bullet@{@}} @result{} @samp{@bullet{}}.@refill

@item 3. Alphabetic commands that require arguments within braces.
These commands start with @@ followed by a letter or a word, followed by an
argument within braces.  For example, the command @code{@@dfn} indicates
the introductory or defining use of a term; it is used as follows: @samp{In
Texinfo, @@@@-commands are @@dfn@{mark-up@} commands.}@refill

@item 4. Alphabetic commands that occupy an entire line.
These commands occupy an entire line.  The line starts with @@,
followed by the name of the command (a word); for example, @code{@@center}
or @code{@@cindex}.  If no argument is needed, the word is followed by
the end of the line.  If there is an argument, it is separated from
the command name by a space.  Braces are not used.@refill
@end table

@cindex Braces and argument syntax
Thus, the alphabetic commands fall into classes that have
different argument syntaxes.  You cannot tell to which class a command
belongs by the appearance of its name, but you can tell by the
command's meaning: if the command stands for a glyph, it is in
class 2 and does not require an argument; if it makes sense to use the
command together with other text as part of a paragraph, the command
is in class 3 and must be followed by an argument in braces;
otherwise, it is in class 4 and uses the rest of the line as its
argument.@refill

The purpose of having a different syntax for commands of classes 3 and
4 is to make Texinfo files easier to read, and also to help the GNU
Emacs paragraph and filling commands work properly.  There is only one
exception to this rule: the command @code{@@refill}, which is always
used at the end of a paragraph immediately following the final period
or other punctuation character.  @code{@@refill} takes no argument and
does @emph{not} require braces.  @code{@@refill} never confuses the
Emacs paragraph commands because it cannot appear at the beginning of
a line.  It is also no longer needed, since all formatters now refill
paragraphs automatically.


@node Tips
@appendix Tips and Hints

Here are some tips for writing Texinfo documentation:@refill

@cindex Tips
@cindex Usage tips
@cindex Hints
@itemize @bullet
@item
Write in the present tense, not in the past or the future.

@item
Write actively!  For example, write ``We recommend that @dots{}'' rather
than ``It is recommended that @dots{}''.

@item
Use 70 or 72 as your fill column.  Longer lines are hard to read.

@item
Include a copyright notice and copying permissions.
@end itemize

@subsubheading Index, Index, Index!

Write many index entries, in different ways.
Readers like indices; they are helpful and convenient.

Although it is easiest to write index entries as you write the body of
the text, some people prefer to write entries afterwards.  In either
case, write an entry before the paragraph to which it applies.  This
way, an index entry points to the first page of a paragraph that is
split across pages.

Here are more hints we have found valuable:

@itemize @bullet
@item
Write each index entry differently, so each entry refers to a different
place in the document.

@item
Write index entries only where a topic is discussed significantly.  For
example, it is not useful to index ``debugging information'' in a
chapter on reporting bugs.  Someone who wants to know about debugging
information will certainly not find it in that chapter.

@item
Consistently capitalize the first word of every concept index entry,
or else consistently use lower case.  Terse entries often call for
lower case; longer entries for capitalization.  Whichever case
convention you use, please use one or the other consistently!  Mixing
the two styles looks bad.

@item
Always capitalize or use upper case for those words in an index for
which this is proper, such as names of countries or acronyms.  Always
use the appropriate case for case-sensitive names, such as those in C or
Lisp.

@item
Write the indexing commands that refer to a whole section immediately
after the section command, and write the indexing commands that refer to
a paragraph before that paragraph.

In the example that follows, a blank line comes after the index
entry for ``Leaping'':

@example
@group
@@section The Dog and the Fox
@@cindex Jumping, in general
@@cindex Leaping

@@cindex Dog, lazy, jumped over
@@cindex Lazy dog jumped over
@@cindex Fox, jumps over dog
@@cindex Quick fox jumps over dog
The quick brown fox jumps over the lazy dog.
@end group
@end example

@noindent
(Note that the example shows entries for the same concept that are
written in different ways---@samp{Lazy dog}, and @samp{Dog, lazy}---so
readers can look up the concept in different ways.)
@end itemize

@subsubheading Blank Lines

@itemize @bullet
@item
Insert a blank line between a sectioning command and the first following
sentence or paragraph, or between the indexing commands associated with
the sectioning command and the first following sentence or paragraph, as
shown in the tip on indexing.  Otherwise, a formatter may fold title and
paragraph together.

@item
Always insert a blank line before an @code{@@table} command and after an
@code{@@end table} command; but never insert a blank line after an
@code{@@table} command or before an @code{@@end table} command.

@need 1000
For example,

@example
@group
Types of fox:

@@table @@samp
@@item Quick
Jump over lazy dogs.
@end group

@group
@@item Brown
Also jump over lazy dogs.
@@end table

@end group
@group
@@noindent
On the other hand, @dots{}
@end group
@end example

Insert blank lines before and after @code{@@itemize} @dots{} @code{@@end
itemize} and @code{@@enumerate} @dots{} @code{@@end enumerate} in the
same way.
@end itemize

@subsubheading Complete Phrases

Complete phrases are easier to read than @dots{}

@itemize @bullet
@item
Write entries in an itemized list as complete sentences; or at least, as
complete phrases.  Incomplete expressions @dots{} awkward @dots{} like
this.

@item
Write the prefatory sentence or phrase for a multi-item list or table as
a complete expression.  Do not write ``You can set:''; instead, write
``You can set these variables:''.  The former expression sounds cut off.
@end itemize

@subsubheading Editions, Dates and Versions

Include edition numbers, version numbers, and dates in the
@code{@@copying} text (for people reading the Texinfo file, and for the
legal copyright in the output files).  Then use @code{@@insertcopying}
in the @code{@@titlepage} section (for people reading the printed
output) and the Top node (for people reading the online output).

It is easiest to do this using @code{@@set} and @code{@@value}.
@xref{value Example, , @code{@@value} Example}, and @ref{GNU Sample Texts}.


@subsubheading Definition Commands

Definition commands are @code{@@deffn}, @code{@@defun},
@code{@@defmac}, and the like, and enable you to write descriptions in
a uniform format.@refill

@itemize @bullet
@item
Write just one definition command for each entity you define with a
definition command.  The automatic indexing feature creates an index
entry that leads the reader to the definition.

@item
Use @code{@@table} @dots{} @code{@@end table} in an appendix that
contains a summary of functions, not @code{@@deffn} or other definition
commands.
@end itemize

@subsubheading Capitalization

@itemize @bullet
@item
Capitalize ``Texinfo''; it is a name.  Do not write the @samp{x} or
@samp{i} in upper case.

@item
Capitalize ``Info''; it is a name.

@item
Write @TeX{} using the @code{@@TeX@{@}} command.  Note the uppercase
@samp{T} and @samp{X}.  This command causes the formatters to
typeset the name according to the wishes of Donald Knuth, who wrote
@TeX{}.
@end itemize

@subsubheading Spaces

Do not use spaces to format a Texinfo file, except inside of
@code{@@example} @dots{} @code{@@end example} and other literal
environments and commands.

@need 700
For example, @TeX{} fills the following:

@example
@group
   @@kbd@{C-x v@}
   @@kbd@{M-x vc-next-action@}
      Perform the next logical operation
      on the version-controlled file
      corresponding to the current buffer.
@end group
@end example

@need 950
@noindent
so it looks like this:

@iftex
@quotation
   @kbd{C-x v}
   @kbd{M-x vc-next-action}
      Perform the next logical operation on the version-controlled file
      corresponding to the current buffer.
@end quotation
@end iftex
@ifnottex
@quotation
`C-x v' `M-x vc-next-action' Perform the next logical operation on the
version-controlled file corresponding to the current buffer.
@end quotation
@end ifnottex

@noindent
In this case, the text should be formatted with
@code{@@table}, @code{@@item}, and @code{@@itemx}, to create a table.


@subsubheading @@code, @@samp, @@var, and @samp{---}

@itemize @bullet
@item
Use @code{@@code} around Lisp symbols, including command names.
For example,

@example
The main function is @@code@{vc-next-action@}, @dots{}
@end example

@item
Avoid putting letters such as @samp{s} immediately after an
@samp{@@code}.  Such letters look bad.

@item
Use @code{@@var} around meta-variables.  Do not write angle brackets
around them.

@item
Use three hyphens in a row, @samp{---}, to indicate a long dash.  @TeX{}
typesets these as a long dash and the Info formatters reduce three
hyphens to two.
@end itemize

@subsubheading Periods Outside of Quotes

Place periods and other punctuation marks @emph{outside} of quotations,
unless the punctuation is part of the quotation.  This practice goes
against publishing conventions in the United States, but enables the
reader to distinguish between the contents of the quotation and the
whole passage.

For example, you should write the following sentence with the period
outside the end quotation marks:

@example
Evidently, @samp{au} is an abbreviation for ``author''.
@end example

@noindent
since @samp{au} does @emph{not} serve as an  abbreviation for
@samp{author.} (with a period following the word).

@subsubheading Introducing New Terms

@itemize @bullet
@item
Introduce new terms so that a reader who does not know them can
understand them from context; or write a definition for the term.

For example, in the following, the terms ``check in'', ``register'' and
``delta'' are all appearing for the first time; the example sentence should be
rewritten so they are understandable.

@quotation
The major function assists you in checking in a file to your
version control system and registering successive sets of changes to
it as deltas.
@end quotation

@item
Use the @code{@@dfn} command around a word being introduced, to indicate
that the reader should not expect to know the meaning already, and
should expect to learn the meaning from this passage.
@end itemize

@subsubheading @@pxref

@c !!! maybe include this in the tips on pxref
@ignore
By the way, it is okay to use pxref with something else in front of
it within the parens, as long as the pxref is followed by the close
paren, and the material inside the parens is not part of a larger
sentence.  Also, you can use xref inside parens as part of a complete
sentence so long as you terminate the cross reference with punctuation.
@end ignore
Absolutely never use @code{@@pxref} except in the special context for
which it is designed: inside parentheses, with the closing parenthesis
following immediately after the closing brace.  One formatter
automatically inserts closing punctuation and the other does not.  This
means that the output looks right both in printed output and in an Info
file, but only when the command is used inside parentheses.

@subsubheading Invoking from a Shell

You can invoke programs such as Emacs, GCC, and @code{gawk} from a
shell.  The documentation for each program should contain a section that
describes this.  Unfortunately, if the node names and titles for these
sections are all different, they are difficult for users to find.

So, there is a convention to name such sections with a phrase beginning
with the word `Invoking', as in `Invoking Emacs'; this way, users can
find the section easily.


@subsubheading ANSI C Syntax

When you use @code{@@example} to describe a C function's calling
conventions, use the ANSI C syntax, like this:@refill

@example
void dld_init (char *@@var@{path@});
@end example

@noindent
And in the subsequent discussion, refer to the argument values by
writing the same argument names, again highlighted with
@code{@@var}.@refill

@need 800
Avoid the obsolete style that looks like this:@refill

@example
#include <dld.h>

dld_init (path)
char *path;
@end example

Also, it is best to avoid writing @code{#include} above the
declaration just to indicate that the function is declared in a
header file.  The practice may give the misimpression that the
@code{#include} belongs near the declaration of the function.  Either
state explicitly which header file holds the declaration or, better
yet, name the header file used for a group of functions at the
beginning of the section that describes the functions.@refill

@subsubheading Bad Examples

Here are several examples of bad writing to avoid:

In this example, say, `` @dots{} you must @code{@@dfn}@{check
in@} the new version.''  That flows better.

@quotation
When you are done editing the file, you must perform a
@code{@@dfn}@{check in@}.
@end quotation

In the following example, say, ``@dots{} makes a unified interface such as VC
mode possible.''

@quotation
SCCS, RCS and other version-control systems all perform similar
functions in broadly similar ways (it is this resemblance which makes
a unified control mode like this possible).
@end quotation

And in this example, you should specify what `it' refers to:

@quotation
If you are working with other people, it assists in coordinating
everyone's changes so they do not step on each other.
@end quotation

@subsubheading And Finally @dots{}

@itemize @bullet
@item
Pronounce @TeX{} as if the @samp{X} were a Greek `chi', as the last
sound in the name `Bach'.  But pronounce Texinfo as in `speck':
``teckinfo''.

@item
Write notes for yourself at the very end of a Texinfo file after the
@code{@@bye}.  None of the formatters process text after the
@code{@@bye}; it is as if the text were within @code{@@ignore} @dots{}
@code{@@end ignore}.
@end itemize


@node Sample Texinfo Files
@appendix Sample Texinfo Files
@cindex Sample Texinfo files

The first example is from the first chapter (@pxref{Short Sample}),
given here in its entirety, without commentary.  The second
includes the full texts to be used in GNU manuals.

@menu
* Short Sample Texinfo File::
* GNU Sample Texts::
* Verbatim Copying License::
* All-permissive Copying License::
@end menu


@node Short Sample Texinfo File
@section Short Sample
@cindex Sample Texinfo file, no comments

Here is a complete, short sample Texinfo file, without any commentary.
You can see this file, with comments, in the first chapter.  @xref{Short
Sample}.

In a nutshell: The @command{makeinfo} program transforms a Texinfo
source file such as this into an Info file or HTML; and @TeX{} typesets
it for a printed manual.


@sp 1
@example
\input texinfo   @@c -*-texinfo-*-
@@c %**start of header
@@setfilename sample.info
@@settitle Sample Manual 1.0
@@c %**end of header

@@copying
This is a short example of a complete Texinfo file.

Copyright @copyright{} 2005 Free Software Foundation, Inc.
@@end copying

@@titlepage
@@title Sample Title
@@page
@@vskip 0pt plus 1filll
@@insertcopying
@@end titlepage

@@c Output the table of the contents at the beginning.
@@contents

@@ifnottex
@@node Top
@@top GNU Sample

@@insertcopying
@@end ifnottex

@@menu
* First Chapter::    The first chapter is the
                      only chapter in this sample.
* Index::            Complete index.
@@end menu


@@node First Chapter
@@chapter First Chapter

@@cindex chapter, first

This is the first chapter.
@@cindex index entry, another

Here is a numbered list.

@@enumerate
@@item
This is the first item.

@@item
This is the second item.
@@end enumerate


@@node Index
@@unnumbered Index

@@printindex cp

@@bye
@end example


@node GNU Sample Texts
@section GNU Sample Texts

@cindex GNU sample texts
@cindex Sample texts, GNU
@cindex Full texts, GNU

Following is a sample Texinfo document with the full texts that should
be used in GNU manuals.

As well as the legal texts, it also serves as a practical example of how
many elements in a GNU system can affect the manual.  If you're not
familiar with all these different elements, don't worry.  They're not
required and a perfectly good manual can be written without them.
They're included here nonetheless because many manuals do (or could)
benefit from them.

@xref{Short Sample}, for a minimal example of a Texinfo file.
@xref{Beginning a File}, for a full explanation of that minimal
example.

Here are some notes on the example:

@itemize @bullet
@item
@cindex $Id
@cindex CVS $Id
@cindex RCS $Id
@cindex Documentation identification
@cindex Identification of documentation
The @samp{$Id:} comment is for the CVS (@pxref{Top,, Overview, cvs,
Concurrent Versions System}) or RCS
(@url{http://www.gnu.org/software/rcs}) version control systems, which
expand it into a string such as:
@example
$Id: texinfo.txi,v 1.225 2008/09/07 22:47:46 karl Exp $
@end example
(This is useful in all sources that use version control, not just manuals.)
You may wish to include the @samp{$Id:} comment in the @code{@@copying}
text, if you want a completely unambiguous reference to the
documentation version.

If you want to literally write @t{@w{$}Id$}, use @code{@@w}:
@code{@@w@{$@}Id$}.  Unfortunately, this technique does not currently
work in plain text output, since it's not clear what should be done.
We hope to find a solution in a future release.

@item
@pindex automake@r{, and version info}
@vindex UPDATED @r{Automake variable}
@vindex VERSION @r{Automake variable}
@pindex time-stamp.el
The @file{version.texi} in the @code{@@include} command is maintained
automatically by Automake (@pxref{Top,, Introduction, automake, GNU
Automake}).  It sets the @samp{VERSION} and @samp{UPDATED} values used
elsewhere.  If your distribution doesn't use Automake, but you do use
Emacs, you may find the time-stamp.el package helpful (@pxref{Time
Stamps,,,emacs,The GNU Emacs Manual}).

@item
The @code{@@syncodeindex} command reflects the recommendation to use
only one index where possible, to make it easier for readers to look up
index entries.

@item
The @code{@@dircategory} is for constructing the Info directory.
@xref{Installing Dir Entries}, which includes a variety of recommended
category names.

@item
The `Invoking' node is a GNU standard to help users find the basic
information about command-line usage of a given program.  @xref{Manual
Structure Details,,,standards, GNU Coding Standards}.

@item
@cindex GNU Free Documentation License, including entire
@cindex Free Documentation License, including entire
It is best to include the entire GNU Free Documentation License in a GNU
manual, unless the manual is only a few pages long.  Of course this
sample is even shorter than that, but it includes the FDL anyway in
order to show one conventional way to do so.  The @file{fdl.texi} file
is available on the GNU machines and in the Texinfo and other GNU
source distributions.

The FDL provides for omitting itself under certain conditions, but in
that case the sample texts given here have to be modified.  @xref{GNU
Free Documentation License}.

@item
If the FSF is not the copyright holder, then use the appropriate name.

@item
If your manual is not published on paper by the FSF, then omit the
last sentence in the Back-Cover Text that talks about copies from GNU
Press.

@item
If your manual has Invariant Sections (again, see the license itself
for details), then change the text here accordingly.

@item
For documents that express your personal views, feelings or experiences,
it is more appropriate to use a license permitting only verbatim
copying, rather than the FDL.  @xref{Verbatim Copying License}.

@end itemize

Here is the sample document:

@verbatim
\input texinfo   @c -*-texinfo-*-
@comment $Id: texinfo.txi,v 1.225 2008/09/07 22:47:46 karl Exp $
@comment %**start of header
@setfilename sample.info
@include version.texi
@settitle GNU Sample @value{VERSION}
@syncodeindex pg cp
@comment %**end of header
@copying
This manual is for GNU Sample (version @value{VERSION}, @value{UPDATED}),
which is an example in the Texinfo documentation.

Copyright @copyright{} 2007 Free Software Foundation, Inc.

@quotation
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover Texts being ``A GNU Manual,''
and with the Back-Cover Texts as in (a) below.  A copy of the
license is included in the section entitled ``GNU Free Documentation
License.''

(a) The FSF's Back-Cover Text is: ``You have the freedom to
copy and modify this GNU manual.  Buying copies from the FSF
supports it in developing GNU and promoting software freedom.''
@end quotation
@end copying

@dircategory Texinfo documentation system
@direntry
* sample: (sample)Invoking sample.
@end direntry

@titlepage
@title GNU Sample
@subtitle for version @value{VERSION}, @value{UPDATED}
@author A.U. Thor (@email{bug-texinfo@@gnu.org})
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@contents

@ifnottex
@node Top
@top GNU Sample

This manual is for GNU Sample (version @value{VERSION}, @value{UPDATED}).
@end ifnottex

@menu
* Invoking sample::
* Copying This Manual::
* Index::
@end menu


@node Invoking sample
@chapter Invoking sample

@pindex sample
@cindex invoking @command{sample}

This is a sample manual.  There is no sample program to
invoke, but if there was, you could see its basic usage
and command line options here.


@node GNU Free Documentation License
@appendix GNU Free Documentation License

@include fdl.texi


@node Index
@unnumbered Index

@printindex cp

@bye
@end verbatim


@node Verbatim Copying License
@section Verbatim Copying License

@cindex Verbatim copying license
@cindex License for verbatim copying

For software manuals and other documentation, it is important to use a
license permitting free redistribution and updating, so that when a free
program is changed, the documentation can be updated as well.

On the other hand, for documents that express your personal views,
feelings or experiences, it is more appropriate to use a license
permitting only verbatim copying.

Here is sample text for such a license permitting verbatim copying only.
This is just the license text itself.  For a complete sample document,
see the previous sections.

@verbatim
@copying
This document is a sample for allowing verbatim copying only.

Copyright @copyright{} 2005 Free Software Foundation, Inc.

@quotation
Permission is granted to make and distribute verbatim copies
of this entire document without royalty provided the
copyright notice and this permission notice are preserved.
@end quotation
@end copying
@end verbatim


@node All-permissive Copying License
@section All-permissive Copying License

@cindex All-permissive copying license
@cindex License for all-permissive copying

For software manuals and other documentation, it is important to use a
license permitting free redistribution and updating, so that when a free
program is changed, the documentation can be updated as well.

On the other hand, for small supporting files, short manuals (under 300
lines long) and rough documentation (README files, INSTALL files, etc.),
the full FDL would be overkill.  They can use a simple all-permissive
license.

Here is sample text for such an all-permissive license.  This is just
the license text itself.  For a complete sample document, see the
previous sections.

@example
Copyright @copyright{} 2005 Free Software Foundation, Inc.

Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.
@end example


@node Include Files
@appendix Include Files
@cindex Include files

When @TeX{} or an Info formatting command sees an @code{@@include}
command in a Texinfo file, it processes the contents of the file named
by the command and incorporates them into the DVI or Info file being
created.  Index entries from the included file are incorporated into
the indices of the output file.

Include files let you keep a single large document as a collection of
conveniently small parts.

@menu
* Using Include Files::         How to use the @code{@@include} command.
* texinfo-multiple-files-update::  How to create and update nodes and
                                     menus when using included files.
* Include Files Requirements::  @code{texinfo-multiple-files-update} needs.
* Sample Include File::         A sample outer file with included files
                                     within it; and a sample included file.
* Include Files Evolution::     How use of the @code{@@include} command
                                     has changed over time.
@end menu

@node Using Include Files
@section How to Use Include Files
@findex include

To include another file within a Texinfo file, write the
@code{@@include} command at the beginning of a line and follow it on
the same line by the name of a file to be included.  For example:

@example
@@include buffers.texi
@end example

The name of the file is taken literally, with a single exception:
@code{@@value@{@var{var}@}} references are expanded.  This makes it
possible to reliably include files in other directories in a
distribution.  @xref{verbatiminclude,,@code{@@verbatiminclude}}, for
an example.

An included file should simply be a segment of text that you expect to
be included as is into the overall or @dfn{outer} Texinfo file; it
should not contain the standard beginning and end parts of a Texinfo
file.  In particular, you should not start an included file with a
line saying @samp{\input texinfo}; if you do, that phrase is inserted
into the output file as is.  Likewise, you should not end an included
file with an @code{@@bye} command; nothing after @code{@@bye} is
formatted.

In the past, you were required to write an @code{@@setfilename} line at the
beginning of an included file, but no longer.  Now, it does not matter
whether you write such a line.  If an @code{@@setfilename} line exists
in an included file, it is ignored.@refill

Conventionally, an included file begins with an @code{@@node} line that
is followed by an @code{@@chapter} line.  Each included file is one
chapter.  This makes it easy to use the regular node and menu creating
and updating commands to create the node pointers and menus within the
included file.  However, the simple Emacs node and menu creating and
updating commands do not work with multiple Texinfo files.  Thus you
cannot use these commands to fill in the `Next', `Previous', and `Up'
pointers of the @code{@@node} line that begins the included file.  Also,
you cannot use the regular commands to create a master menu for the
whole file.  Either you must insert the menus and the `Next',
`Previous', and `Up' pointers by hand, or you must use the GNU Emacs
Texinfo mode command, @code{texinfo-multiple-files-update}, that is
designed for @code{@@include} files.@refill

When an included file does not have any node lines in it, the
multiple files update command does not try to create a menu entry
for it.  Consequently, you can include any file, such as a
version or an update file without node lines, not just files that
are chapters.  Small includable files like this are created by
Automake (@pxref{GNU Sample Texts}).


@node texinfo-multiple-files-update
@section @code{texinfo-multiple-files-update}
@findex texinfo-multiple-files-update

GNU Emacs Texinfo mode provides the @code{texinfo-multiple-files-update}
command.  This command creates or updates `Next', `Previous', and `Up'
pointers of included files as well as those in the outer or overall
Texinfo file, and it creates or updates a main menu in the outer file.
Depending whether you call it with optional arguments, the command
updates only the pointers in the first @code{@@node} line of the
included files or all of them:@refill

@table @kbd
@item M-x texinfo-multiple-files-update
Called without any arguments:@refill

@itemize @minus
@item
Create or update the `Next', `Previous', and `Up' pointers of the
first @code{@@node} line in each file included in an outer or overall
Texinfo file.@refill

@item
Create or update the `Top' level node pointers of the outer or
overall file.@refill

@item
Create or update a main menu in the outer file.@refill
@end itemize

@item C-u M-x texinfo-multiple-files-update
Called with @kbd{C-u} as a prefix argument:

@itemize @minus{}
@item
Create or update pointers in the first @code{@@node} line in each
included file.

@item
Create or update the `Top' level node pointers of the outer file.

@item
Create and insert a master menu in the outer file.  The master menu
is made from all the menus in all the included files.@refill
@end itemize

@item C-u 8 M-x texinfo-multiple-files-update
Called with a numeric prefix argument, such as @kbd{C-u 8}:

@itemize @minus
@item
Create or update @strong{all} the `Next', `Previous', and `Up' pointers
of all the included files.@refill

@item
Create or update @strong{all} the menus of all the included
files.@refill

@item
Create or update the `Top' level node pointers of the outer or
overall file.@refill

@item
And then create a master menu in the outer file.  This is similar to
invoking @code{texinfo-master-menu} with an argument when you are
working with just one file.@refill
@end itemize
@end table

Note the use of the prefix argument in interactive use: with a regular
prefix argument, just @w{@kbd{C-u}}, the
@code{texinfo-multiple-files-update} command inserts a master menu;
with a numeric prefix argument, such as @kbd{C-u 8}, the command
updates @strong{every} pointer and menu in @strong{all} the files and then inserts a
master menu.@refill


@node Include Files Requirements
@section Include Files Requirements
@cindex Include files requirements
@cindex Requirements for include files

If you plan to use the @code{texinfo-multiple-files-update} command,
the outer Texinfo file that lists included files within it should
contain nothing but the beginning and end parts of a Texinfo file, and
a number of @code{@@include} commands listing the included files.  It
should not even include indices, which should be listed in an included
file of their own.@refill

Moreover, each of the included files must contain exactly one highest
level node (conventionally, @code{@@chapter} or equivalent),
and this node must be the first node in the included file.
Furthermore, each of these highest level nodes in each included file
must be at the same hierarchical level in the file structure.
Usually, each is an @code{@@chapter}, an @code{@@appendix}, or an
@code{@@unnumbered} node.  Thus, normally, each included file contains
one, and only one, chapter or equivalent-level node.@refill

The outer file should contain only @emph{one} node, the `Top' node.  It
should @emph{not} contain any nodes besides the single `Top' node.  The
@code{texinfo-multiple-files-update} command will not process
them.@refill


@node Sample Include File
@section Sample File with @code{@@include}
@cindex Sample @code{@@include} file
@cindex Include file sample
@cindex @code{@@include} file sample

Here is an example of an outer Texinfo file with @code{@@include} files
within it before running @code{texinfo-multiple-files-update}, which
would insert a main or master menu:

@example
@group
\input texinfo @@c -*-texinfo-*-
@c %**start of header
@@setfilename include-example.info
@@settitle Include Example
@c %**end of header
@end group

... @xref{Sample Texinfo Files}, for
examples of the rest of the frontmatter ...

@group
@@ifnottex
@@node Top
@@top Include Example
@@end ifnottex
@end group

@group
@@include foo.texinfo
@@include bar.texinfo
@@include concept-index.texinfo
@@bye
@end group
@end example

An included file, such as @file{foo.texinfo}, might look like this:

@example
@group
@@node First
@@chapter First Chapter

Contents of first chapter @dots{}
@end group
@end example

The full contents of @file{concept-index.texinfo} might be as simple as this:

@example
@group
@@node Concept Index
@@unnumbered Concept Index

@@printindex cp
@end group
@end example

The outer Texinfo source file for @cite{The GNU Emacs Lisp Reference
Manual} is named @file{elisp.texi}.  This outer file contains a master
menu with 417 entries and a list of 41 @code{@@include}
files.


@node Include Files Evolution
@section Evolution of Include Files

When Info was first created, it was customary to create many small
Info files on one subject.  Each Info file was formatted from its own
Texinfo source file.  This custom meant that Emacs did not need to
make a large buffer to hold the whole of a large Info file when
someone wanted information; instead, Emacs allocated just enough
memory for the small Info file that contained the particular
information sought.  This way, Emacs could avoid wasting memory.@refill

References from one file to another were made by referring to the file
name as well as the node name. (@xref{Other Info Files, , Referring to
Other Info Files}.  Also, see @ref{Four and Five Arguments, ,
@code{@@xref} with Four and Five Arguments}.)@refill

Include files were designed primarily as a way to create a single,
large printed manual out of several smaller Info files.  In a printed
manual, all the references were within the same document, so @TeX{}
could automatically determine the references' page numbers.  The Info
formatting commands used include files only for creating joint
indices; each of the individual Texinfo files had to be formatted for
Info individually.  (Each, therefore, required its own
@code{@@setfilename} line.)@refill

However, because large Info files are now split automatically, it is
no longer necessary to keep them small.@refill

Nowadays, multiple Texinfo files are used mostly for large documents,
such as @cite{The GNU Emacs Lisp Reference Manual}, and for projects
in which several different people write different sections of a
document simultaneously.@refill

In addition, the Info formatting commands have been extended to work
with the @code{@@include} command so as to create a single large Info
file that is split into smaller files if necessary.  This means that
you can write menus and cross references without naming the different
Texinfo files.@refill


@node Headings
@appendix Page Headings
@cindex Headings
@cindex Footings
@cindex Page numbering
@cindex Page headings
@cindex Formatting headings and footings

Most printed manuals contain headings along the top of every page
except the title and copyright pages.  Some manuals also contain
footings.  (Headings and footings have no meaning to Info, which is
not paginated.)@refill

@menu
* Headings Introduced::         Conventions for using page headings.
* Heading Format::              Standard page heading formats.
* Heading Choice::              How to specify the type of page heading.
* Custom Headings::             How to create your own headings and footings.
@end menu

@node Headings Introduced
@section Headings Introduced

Texinfo provides standard page heading formats for manuals that are
printed on one side of each sheet of paper and for manuals that are
printed on both sides of the paper.  Typically, you will use these
formats, but you can specify your own format if you wish.@refill

In addition, you can specify whether chapters should begin on a new
page, or merely continue the same page as the previous chapter; and if
chapters begin on new pages, you can specify whether they must be
odd-numbered pages.@refill

By convention, a book is printed on both sides of each sheet of paper.
When you open a book, the right-hand page is odd-numbered, and
chapters begin on right-hand pages---a preceding left-hand page is
left blank if necessary.  Reports, however, are often printed on just
one side of paper, and chapters begin on a fresh page immediately
following the end of the preceding chapter.  In short or informal
reports, chapters often do not begin on a new page at all, but are
separated from the preceding text by a small amount of whitespace.@refill

The @code{@@setchapternewpage} command controls whether chapters begin
on new pages, and whether one of the standard heading formats is used.
In addition, Texinfo has several heading and footing commands that you
can use to generate your own heading and footing formats.@refill

In Texinfo, headings and footings are single lines at the tops and
bottoms of pages; you cannot create multiline headings or footings.
Each header or footer line is divided into three parts: a left part, a
middle part, and a right part.  Any part, or a whole line, may be left
blank.  Text for the left part of a header or footer line is set
flushleft; text for the middle part is centered; and, text for the
right part is set flushright.@refill

@node Heading Format
@comment  node-name,  next,  previous,  up
@section Standard Heading Formats

Texinfo provides two standard heading formats, one for manuals printed
on one side of each sheet of paper, and the other for manuals printed
on both sides of the paper.

By default, nothing is specified for the footing of a Texinfo file,
so the footing remains blank.@refill

The standard format for single-sided printing consists of a header
line in which the left-hand part contains the name of the chapter, the
central part is blank, and the right-hand part contains the page
number.@refill

@need 950
A single-sided page looks like this:

@example
@group
  _______________________
 |                       |
 | chapter   page number |
 |                       |
 | Start of text ...     |
 | ...                   |
 |                       |
@end group
@end example

The standard format for two-sided printing depends on whether the page
number is even or odd.  By convention, even-numbered pages are on the
left- and odd-numbered pages are on the right.  (@TeX{} will adjust the
widths of the left- and right-hand margins.  Usually, widths are
correct, but during double-sided printing, it is wise to check that
pages will bind properly---sometimes a printer will produce output in
which the even-numbered pages have a larger right-hand margin than the
odd-numbered pages.)@refill

In the standard double-sided format, the left part of the left-hand
(even-numbered) page contains the page number, the central part is
blank, and the right part contains the title (specified by the
@code{@@settitle} command).  The left part of the right-hand
(odd-numbered) page contains the name of the chapter, the central part
is blank, and the right part contains the page number.@refill

@need 750
Two pages, side by side as in an open book, look like this:@refill

@example
@group
  _______________________     _______________________
 |                       |   |                       |
 | page number     title |   | chapter   page number |
 |                       |   |                       |
 | Start of text ...     |   | More  text ...        |
 | ...                   |   | ...                   |
 |                       |   |                       |
@end group
@end example

@noindent
The chapter name is preceded by the word ``Chapter'', the chapter number
and a colon.  This makes it easier to keep track of where you are in the
manual.@refill

@node Heading Choice
@comment  node-name,  next,  previous,  up
@section Specifying the Type of Heading

@TeX{} does not begin to generate page headings for a standard Texinfo
file until it reaches the @code{@@end titlepage} command.  Thus, the
title and copyright pages are not numbered.  The @code{@@end
titlepage} command causes @TeX{} to begin to generate page headings
according to a standard format specified by the
@code{@@setchapternewpage} command that precedes the
@code{@@titlepage} section.@refill

@need 1000
There are four possibilities:@refill

@table @asis
@item No @code{@@setchapternewpage} command
Cause @TeX{} to specify the single-sided heading format, with chapters
on new pages. This is the same as @code{@@setchapternewpage on}.@refill

@item @code{@@setchapternewpage on}
Specify the single-sided heading format, with chapters on new pages.@refill

@item @code{@@setchapternewpage off}
Cause @TeX{} to start a new chapter on the same page as the last page of
the preceding chapter, after skipping some vertical whitespace.  Also
cause @TeX{} to typeset for single-sided printing.  (You can override
the headers format with the @code{@@headings double} command; see
@ref{headings on off, , The @code{@@headings} Command}.)@refill

@item @code{@@setchapternewpage odd}
Specify the double-sided heading format, with chapters on new pages.@refill
@end table

@noindent
Texinfo lacks an @code{@@setchapternewpage even} command.@refill

@node Custom Headings
@comment  node-name,  next,  previous,  up
@section How to Make Your Own Headings

You can use the standard headings provided with Texinfo or specify
your own.  By default, Texinfo has no footers, so if you specify them,
the available page size for the main text will be slightly reduced.

Texinfo provides six commands for specifying headings and
footings:
@itemize @bullet
@item
@code{@@everyheading} @code{@@everyfooting} generate page headers and
footers that are the same for both even- and odd-numbered pages.
@item
@code{@@evenheading} and @code{@@evenfooting} command generate headers
and footers for even-numbered (left-hand) pages.
@item
@code{@@oddheading} and @code{@@oddfooting} generate headers and footers
for odd-numbered (right-hand) pages.
@end itemize

Write custom heading specifications in the Texinfo file immediately
after the @code{@@end titlepage} command.
You must cancel the predefined heading commands with the
@code{@@headings off} command before defining your own
specifications.

@need 1000
Here is how to tell @TeX{} to place the chapter name at the left, the
page number in the center, and the date at the right of every header
for both even- and odd-numbered pages:

@example
@group
@@headings off
@@everyheading @@thischapter @@| @@thispage @@| @@today@{@}
@end group
@end example

@noindent
You need to divide the left part from the central part and the central
part from the right part by inserting @samp{@@|} between parts.
Otherwise, the specification command will not be able to tell where
the text for one part ends and the next part begins.

Each part can contain text or @@-commands.  The text
is printed as if the part were within an ordinary paragraph in the
body of the page.  The @@-commands replace
themselves with the page number, date, chapter name, or
whatever.

@need 950
Here are the six heading and footing commands:

@table @code
@item @@everyheading @var{left} @@| @var{center} @@| @var{right}
@itemx @@everyfooting @var{left} @@| @var{center} @@| @var{right}
@findex everyheading
@findex everyfooting
The `every' commands specify the format for both even- and odd-numbered
pages.  These commands are for documents that are printed on one side
of each sheet of paper, or for documents in which you want symmetrical
headers or footers.

@item @@evenheading @var{left} @@| @var{center} @@| @var{right}
@itemx @@oddheading  @var{left} @@| @var{center} @@| @var{right}
@itemx @@evenfooting @var{left} @@| @var{center} @@| @var{right}
@itemx @@oddfooting  @var{left} @@| @var{center} @@| @var{right}
@findex evenheading
@findex evenfooting
@findex oddheading
@findex oddfooting
The `even' and `odd' commands specify the format for even-numbered
pages and odd-numbered pages.  These commands are for books and
manuals that are printed on both sides of each sheet of paper.
@end table

Use the @samp{@@this@dots{}} series of @@-commands to
provide the names of chapters
and sections and the page number.  You can use the
@samp{@@this@dots{}} commands in the left, center, or right portions
of headers and footers, or anywhere else in a Texinfo file so long as
they are between @code{@@iftex} and @code{@@end iftex} commands.

@need 1000
Here are the @samp{@@this@dots{}} commands:

@table @code
@item @@thispage
@findex thispage
Expands to the current page number.

@item @@thissectionname
@findex thissectionname
Expands to the name of the current section.

@item @@thissectionnum
@findex thissectionnum
Expands to the number of the current section.

@item @@thissection
@findex thissection
Expands to the number and name of the current section, in the format
`Section 1: Title'.

@item @@thischaptername
@findex thischaptername
Expands to the name of the current chapter.

@item @@thischapternum
@findex thischapternum
Expands to the number of the current chapter, or letter of the current
appendix.

@item @@thischapter
@findex thischapter
Expands to the number and name of the current
chapter, in the format `Chapter 1: Title'.

@item @@thistitle
@findex thistitle
Expands to the name of the document, as specified by the
@code{@@settitle} command.

@item @@thisfile
@findex thisfile
For @code{@@include} files only: expands to the name of the current
@code{@@include} file.  If the current Texinfo source file is not an
@code{@@include} file, this command has no effect.  This command does
@emph{not} provide the name of the current Texinfo source file unless
it is an @code{@@include} file.  (@xref{Include Files}, for more
information about @code{@@include} files.)
@end table

@noindent
You can also use the @code{@@today@{@}} command, which expands to the
current date, in `1 Jan 1900' format.
@findex today

Other @@-commands and text are printed in a header or footer just as
if they were in the body of a page.  It is useful to incorporate text,
particularly when you are writing drafts:

@example
@group
@@headings off
@@everyheading @@emph@{Draft!@} @@| @@thispage @@| @@thischapter
@@everyfooting @@| @@| Version: 0.27: @@today@{@}
@end group
@end example

Beware of overlong titles: they may overlap another part of the
header or footer and blot it out.

If you have very short chapters and/or sections, several of them can
appear on a single page.  You can specify which chapters and sections
you want @code{@@thischapter}, @code{@@thissection} and other such
macros to refer to on such pages as follows:

@table @code
@item @@everyheadingmarks @var{ref}
@itemx @@everyfootingmarks @var{ref}
@findex everyheadingmarks
@findex everyfootingmarks
The @var{ref} argument can be either @code{top} (the @code{@@this...}
commands will refer to the chapter/section at the top of a page) or
@code{bottom} (the commands will reflect the situation at the bottom
of a page).  These @samp{@@every...} commands specify what to do on
both even- and odd-numbered pages.

@item @@evenheadingmarks @var{ref}
@itemx @@oddheadingmarks @var{ref}
@itemx @@evenfootingmarks @var{ref}
@itemx @@oddfootingmarks @var{ref}
@findex evenheadingmarks
@findex oddheadingmarks
@findex evenfootingmarks
@findex oddfootingmarks
These @samp{@@even...} and @samp{@@odd...} commands specify what to do
on only even- or odd-numbered pages, respectively.  The @var{ref}
argument is the same as with the @samp{@@every...} commands.
@end table

Write these commands immediately after the @code{@@...contents}
commands, or after the @code{@@end titlepage} command if you don't
have a table of contents or if it is printed at the end of your
manual.

By default the @code{@@this...} commands reflect the situation at the
bottom of a page both in headings and in footings.


@node Catching Mistakes
@appendix Formatting Mistakes
@cindex Structure, catching mistakes in
@cindex Nodes, catching mistakes
@cindex Catching mistakes
@cindex Correcting mistakes
@cindex Mistakes, catching
@cindex Problems, catching
@cindex Debugging the Texinfo structure

Besides mistakes in the content of your documentation, there are two
kinds of mistake you can make with Texinfo: you can make mistakes with
@@-commands, and you can make mistakes with the structure of the nodes
and chapters.

Emacs has two tools for catching the @@-command mistakes and two for
catching structuring mistakes.@refill

For finding problems with @@-commands, you can run @TeX{} or a region
formatting command on the region that has a problem; indeed, you can
run these commands on each region as you write it.@refill

For finding problems with the structure of nodes and chapters, you can use
@kbd{C-c C-s} (@code{texinfo-show-structure}) and the related @code{occur}
command and you can use the @kbd{M-x Info-validate} command.@refill

@menu
* makeinfo Preferred::          @code{makeinfo} finds errors.
* Debugging with Info::         How to catch errors with Info formatting.
* Debugging with TeX::          How to catch errors with @TeX{} formatting.
* Using texinfo-show-structure::  How to use @code{texinfo-show-structure}.
* Using occur::                 How to list all lines containing a pattern.
* Running Info-Validate::       How to find badly referenced nodes.
@end menu


@node makeinfo Preferred
@section @code{makeinfo} Find Errors

The @code{makeinfo} program does an excellent job of catching errors
and reporting them---far better than @code{texinfo-format-region} or
@code{texinfo-format-buffer}.  In addition, the various functions for
automatically creating and updating node pointers and menus remove
many opportunities for human error.@refill

If you can, use the updating commands to create and insert pointers
and menus.  These prevent many errors.  Then use @code{makeinfo} (or
its Texinfo mode manifestations, @code{makeinfo-region} and
@code{makeinfo-buffer}) to format your file and check for other
errors.  This is the best way to work with Texinfo.  But if you
cannot use @code{makeinfo}, or your problem is very puzzling, then you
may want to use the tools described in this appendix.@refill

@node Debugging with Info
@comment  node-name,  next,  previous,  up
@section Catching Errors with Info Formatting
@cindex Catching errors with Info formatting
@cindex Debugging with Info formatting

After you have written part of a Texinfo file, you can use the
@code{texinfo-format-region} or the @code{makeinfo-region} command to
see whether the region formats properly.@refill

Most likely, however, you are reading this section because for some
reason you cannot use the @code{makeinfo-region} command; therefore, the
rest of this section presumes that you are using
@code{texinfo-format-region}.@refill

If you have made a mistake with an @@-command,
@code{texinfo-format-region} will stop processing at or after the
error and display an error message.  To see where in the buffer the
error occurred, switch to the @samp{*Info Region*} buffer; the cursor
will be in a position that is after the location of the error.  Also,
the text will not be formatted after the place where the error
occurred (or more precisely, where it was detected).@refill

For example, if you accidentally end a menu with the command @code{@@end
menus} with an `s' on the end, instead of with @code{@@end menu}, you
will see an error message that says:@refill

@example
@@end menus is not handled by texinfo
@end example

@noindent
The cursor will stop at the point in the buffer where the error
occurs, or not long after it.  The buffer will look like this:@refill

@example
@group
---------- Buffer: *Info Region* ----------
* Menu:

* Using texinfo-show-structure::  How to use
                                 `texinfo-show-structure'
                                 to catch mistakes.
* Running Info-Validate::         How to check for
                                 unreferenced nodes.
@@end menus
@point{}
---------- Buffer: *Info Region* ----------
@end group
@end example

The @code{texinfo-format-region} command sometimes provides slightly
odd error messages.  For example, the following cross reference fails to format:@refill

@example
(@@xref@{Catching Mistakes, for more info.)
@end example

@noindent
In this case, @code{texinfo-format-region} detects the missing closing
brace but displays a message that says @samp{Unbalanced parentheses}
rather than @samp{Unbalanced braces}.  This is because the formatting
command looks for mismatches between braces as if they were
parentheses.@refill

Sometimes @code{texinfo-format-region} fails to detect mistakes.  For
example, in the following, the closing brace is swapped with the
closing parenthesis:@refill

@example
(@@xref@{Catching Mistakes), for more info.@}
@end example

@noindent
Formatting produces:
@example
(*Note for more info.: Catching Mistakes)
@end example

The only way for you to detect this error is to realize that the
reference should have looked like this:@refill

@example
(*Note Catching Mistakes::, for more info.)
@end example

Incidentally, if you are reading this node in Info and type @kbd{f
@key{RET}} (@code{Info-follow-reference}), you will generate an error
message that says:

@example
No such node: "Catching Mistakes) The only way @dots{}
@end example

@noindent
This is because Info perceives the example of the error as the first
cross reference in this node and if you type a @key{RET} immediately
after typing the Info @kbd{f} command, Info will attempt to go to the
referenced node.  If you type @kbd{f catch @key{TAB} @key{RET}}, Info
will complete the node name of the correctly written example and take
you to the `Catching Mistakes' node.  (If you try this, you can return
from the `Catching Mistakes' node by typing @kbd{l}
(@code{Info-last}).)

@c !!! section on using Elisp debugger ignored.
@ignore
Sometimes @code{texinfo-format-region} will stop long after the
original error; this is because it does not discover the problem until
then.  In this case, you will need to backtrack.@refill

@c menu
@c * Using the Emacs Lisp Debugger::  How to use the Emacs Lisp debugger.
@c end menu

@c node Using the Emacs Lisp Debugger
@c appendixsubsec Using the Emacs Lisp Debugger
@c index Using the Emacs Lisp debugger
@c index Emacs Lisp debugger
@c index Debugger, using the Emacs Lisp

If an error is especially elusive, you can turn on the Emacs Lisp
debugger and look at the backtrace; this tells you where in the
@code{texinfo-format-region} function the problem occurred.  You can
turn on the debugger with the command:@refill

@example
M-x set-variable @key{RET} debug-on-error @key{RET} t @key{RET}
@end example

@noindent
and turn it off with

@example
M-x set-variable @key{RET} debug-on-error @key{RET} nil @key{RET}
@end example

Often, when you are using the debugger, it is easier to follow what is
going on if you use the Emacs Lisp files that are not byte-compiled.
The byte-compiled sources send octal numbers to the debugger that may
look mysterious.  To use the uncompiled source files, load
@file{texinfmt.el} and @file{texinfo.el} with the @kbd{M-x load-file}
command.@refill

The debugger will not catch an error if @code{texinfo-format-region}
does not detect one.  In the example shown above,
@code{texinfo-format-region} did not find the error when the whole
list was formatted, but only when part of the list was formatted.
When @code{texinfo-format-region} did not find an error, the debugger
did not find one either. @refill

However, when @code{texinfo-format-region} did report an error, it
invoked the debugger.  This is the backtrace it produced:@refill

@example
---------- Buffer: *Backtrace* ----------
Signalling: (search-failed "[@},]")
 re-search-forward("[@},]")
 (while ...)
 (let ...)
 texinfo-format-parse-args()
 (let ...)
 texinfo-format-xref()
 funcall(texinfo-format-xref)
 (if ...)
 (let ...)
 (if ...)
 (while ...)
 texinfo-format-scan()
 (save-excursion ...)
 (let ...)
 texinfo-format-region(103370 103631)
* call-interactively(texinfo-format-region)
---------- Buffer: *Backtrace* ----------
@end example

The backtrace is read from the bottom up.
@code{texinfo-format-region} was called interactively; and it, in
turn, called various functions, including @code{texinfo-format-scan},
@code{texinfo-format-xref} and @code{texinfo-format-parse-args}.
Inside the function @code{texinfo-format-parse-args}, the function
@code{re-search-forward} was called; it was this function that could
not find the missing right-hand brace.@refill

@xref{Lisp Debug, , Debugging Emacs Lisp, emacs, The GNU Emacs
Manual}, for more information.@refill
@end ignore

@node Debugging with TeX
@comment  node-name,  next,  previous,  up
@section Catching Errors with @TeX{} Formatting
@cindex Catching errors with @TeX{} formatting
@cindex Debugging with @TeX{} formatting

You can also catch mistakes when you format a file with @TeX{}.@refill

Usually, you will want to do this after you have run
@code{texinfo-format-buffer} (or, better, @code{makeinfo-buffer}) on
the same file, because @code{texinfo-format-buffer} sometimes displays
error messages that make more sense than @TeX{}.  (@xref{Debugging
with Info}, for more information.)@refill

For example, @TeX{} was run on a Texinfo file, part of which is shown
here:@refill

@example
---------- Buffer: texinfo.texi ----------
name of the Texinfo file as an extension.  The
@@samp@{??@} are `wildcards' that cause the shell to
substitute all the raw index files.  (@@xref@{sorting
indices, for more information about sorting
indices.)@@refill
---------- Buffer: texinfo.texi ----------
@end example

@noindent
(The cross reference lacks a closing brace.)
@TeX{} produced the following output, after which it stopped:@refill

@example
---------- Buffer: *tex-shell* ----------
Runaway argument?
@{sorting indices, for more information about sorting
indices.) @@refill @@ETC.
! Paragraph ended before @@xref was complete.
<to be read again>
                  @@par
l.27

?
---------- Buffer: *tex-shell* ----------
@end example

In this case, @TeX{} produced an accurate and
understandable error message:

@example
Paragraph ended before @@xref was complete.
@end example

@noindent
@samp{@@par} is an internal @TeX{} command of no relevance to Texinfo.
@samp{l.27} means that @TeX{} detected the problem on line 27 of the
Texinfo file.  The @samp{?} is the prompt @TeX{} uses in this
circumstance.@refill

Unfortunately, @TeX{} is not always so helpful, and sometimes you must
truly be a Sherlock Holmes to discover what went wrong.@refill

In any case, if you run into a problem like this, you can do one of three
things.@refill

@enumerate
@item
You can tell @TeX{} to continue running and ignore just this error by
typing @key{RET} at the @samp{?} prompt.@refill

@item
You can tell @TeX{} to continue running and to ignore all errors as best
it can by typing @kbd{r @key{RET}} at the @samp{?} prompt.@refill

This is often the best thing to do.  However, beware: the one error
may produce a cascade of additional error messages as its consequences
are felt through the rest of the file.  To stop @TeX{} when it is
producing such an avalanche of error messages, type @kbd{C-c} (or
@kbd{C-c C-c}, if you are running a shell inside Emacs).

@item
You can tell @TeX{} to stop this run by typing @kbd{x @key{RET}}
at the @samp{?} prompt.@refill
@end enumerate

If you are running @TeX{} inside Emacs, you need to switch to the shell
buffer and line at which @TeX{} offers the @samp{?} prompt.

Sometimes @TeX{} will format a file without producing error messages even
though there is a problem.  This usually occurs if a command is not ended
but @TeX{} is able to continue processing anyhow.  For example, if you fail
to end an itemized list with the @code{@@end itemize} command, @TeX{} will
write a DVI file that you can print out.  The only error message that
@TeX{} will give you is the somewhat mysterious comment that@refill

@example
(@@end occurred inside a group at level 1)
@end example

@noindent
However, if you print the DVI file, you will find that the text
of the file that follows the itemized list is entirely indented as if
it were part of the last item in the itemized list.  The error message
is the way @TeX{} says that it expected to find an @code{@@end}
command somewhere in the file; but that it could not determine where
it was needed.@refill

Another source of notoriously hard-to-find errors is a missing
@code{@@end group} command.  If you ever are stumped by
incomprehensible errors, look for a missing @code{@@end group} command
first.@refill

If the Texinfo file lacks header lines,
@TeX{} may stop in the
beginning of its run and display output that looks like the following.
The @samp{*} indicates that @TeX{} is waiting for input.@refill

@example
This is TeX, Version 3.14159 (Web2c 7.0)
(test.texinfo [1])
*
@end example

@noindent
In this case, simply type @kbd{\end @key{RET}} after the asterisk.  Then
write the header lines in the Texinfo file and run the @TeX{} command
again. (Note the use of the backslash, @samp{\}.  @TeX{} uses @samp{\}
instead of @samp{@@}; and in this circumstance, you are working
directly with @TeX{}, not with Texinfo.)@refill

@node Using texinfo-show-structure
@comment  node-name,  next,  previous,  up
@section Using @code{texinfo-show-structure}
@cindex Showing the structure of a file
@findex texinfo-show-structure

It is not always easy to keep track of the nodes, chapters, sections, and
subsections of a Texinfo file.  This is especially true if you are revising
or adding to a Texinfo file that someone else has written.@refill

In GNU Emacs, in Texinfo mode, the @code{texinfo-show-structure}
command lists all the lines that begin with the @@-commands that
specify the structure: @code{@@chapter}, @code{@@section},
@code{@@appendix}, and so on.  With an argument (@w{@kbd{C-u}}
as prefix argument, if interactive),
the command also shows the @code{@@node} lines.  The
@code{texinfo-show-structure} command is bound to @kbd{C-c C-s} in
Texinfo mode, by default.@refill

The lines are displayed in a buffer called the @samp{*Occur*} buffer,
indented by hierarchical level.  For example, here is a part of what was
produced by running @code{texinfo-show-structure} on this manual:@refill

@example
@group
Lines matching "^@@\\(chapter \\|sect\\|subs\\|subh\\|
unnum\\|major\\|chapheading \\|heading \\|appendix\\)"
in buffer texinfo.texi.
@dots{}
4177:@@chapter Nodes
4198:    @@heading Two Paths
4231:    @@section Node and Menu Illustration
4337:    @@section The @@code@{@@@@node@} Command
4393:        @@subheading Choosing Node and Pointer Names
4417:        @@subsection How to Write an @@code@{@@@@node@} Line
4469:        @@subsection @@code@{@@@@node@} Line Tips
@dots{}
@end group
@end example

This says that lines 4337, 4393, and 4417 of @file{texinfo.texi} begin
with the @code{@@section}, @code{@@subheading}, and @code{@@subsection}
commands respectively.  If you move your cursor into the @samp{*Occur*}
window, you can position the cursor over one of the lines and use the
@kbd{C-c C-c} command (@code{occur-mode-goto-occurrence}), to jump to
the corresponding spot in the Texinfo file.  @xref{Other Repeating
Search, , Using Occur, emacs, The GNU Emacs Manual}, for more
information about @code{occur-mode-goto-occurrence}.@refill

The first line in the @samp{*Occur*} window describes the @dfn{regular
expression} specified by @var{texinfo-heading-pattern}.  This regular
expression is the pattern that @code{texinfo-show-structure} looks for.
@xref{Regexps, , Using Regular Expressions, emacs, The GNU Emacs Manual},
for more information.@refill

When you invoke the @code{texinfo-show-structure} command, Emacs will
display the structure of the whole buffer.  If you want to see the
structure of just a part of the buffer, of one chapter, for example,
use the @kbd{C-x n n} (@code{narrow-to-region}) command to mark the
region.  (@xref{Narrowing, , , emacs, The GNU Emacs Manual}.)  This is
how the example used above was generated.  (To see the whole buffer
again, use @kbd{C-x n w} (@code{widen}).)@refill

If you call @code{texinfo-show-structure} with a prefix argument by
typing @w{@kbd{C-u C-c C-s}}, it will list lines beginning with
@code{@@node} as well as the lines beginning with the @@-sign commands
for @code{@@chapter}, @code{@@section}, and the like.@refill

You can remind yourself of the structure of a Texinfo file by looking at
the list in the @samp{*Occur*} window; and if you have mis-named a node
or left out a section, you can correct the mistake.@refill

@node Using occur
@comment  node-name,  next,  previous,  up
@section Using @code{occur}
@cindex Occurrences, listing with @code{@@occur}
@findex occur

Sometimes the @code{texinfo-show-structure} command produces too much
information.  Perhaps you want to remind yourself of the overall structure
of a Texinfo file, and are overwhelmed by the detailed list produced by
@code{texinfo-show-structure}.  In this case, you can use the @code{occur}
command directly.  To do this, type@refill

@example
@kbd{M-x occur}
@end example

@noindent
and then, when prompted, type a @dfn{regexp}, a regular expression for
the pattern you want to match.  (@xref{Regexps, , Regular Expressions,
emacs, The GNU Emacs Manual}.)  The @code{occur} command works from
the current location of the cursor in the buffer to the end of the
buffer.  If you want to run @code{occur} on the whole buffer, place
the cursor at the beginning of the buffer.@refill

For example, to see all the lines that contain the word
@samp{@@chapter} in them, just type @samp{@@chapter}.  This will
produce a list of the chapters.  It will also list all the sentences
with @samp{@@chapter} in the middle of the line.@refill

If you want to see only those lines that start with the word
@samp{@@chapter}, type @samp{^@@chapter} when prompted by
@code{occur}.  If you want to see all the lines that end with a word
or phrase, end the last word with a @samp{$}; for example,
@samp{catching mistakes$}.  This can be helpful when you want to see
all the nodes that are part of the same chapter or section and
therefore have the same `Up' pointer.@refill

@xref{Other Repeating Search, , Using Occur, emacs , The GNU Emacs Manual},
for more information.@refill

@node Running Info-Validate
@comment  node-name,  next,  previous,  up
@section Finding Badly Referenced Nodes
@findex Info-validate
@cindex Nodes, checking for badly referenced
@cindex Checking for badly referenced nodes
@cindex Looking for badly referenced nodes
@cindex Finding badly referenced nodes
@cindex Badly referenced nodes

You can use the @code{Info-validate} command to check whether any of
the `Next', `Previous', `Up' or other node pointers fail to point to a
node.  This command checks that every node pointer points to an
existing node.  The @code{Info-validate} command works only on Info
files, not on Texinfo files.@refill

The @code{makeinfo} program validates pointers automatically, so you
do not need to use the @code{Info-validate} command if you are using
@code{makeinfo}.  You only may need to use @code{Info-validate} if you
are unable to run @code{makeinfo} and instead must create an Info file
using @code{texinfo-format-region} or @code{texinfo-format-buffer}, or
if you write an Info file from scratch.@refill

@menu
* Using Info-validate::         How to run @code{Info-validate}.
* Unsplit::                     How to create an unsplit file.
* Tagifying::                   How to tagify a file.
* Splitting::                   How to split a file manually.
@end menu

@node Using Info-validate
@subsection Running @code{Info-validate}
@cindex Running @code{Info-validate}
@cindex Info validating a large file
@cindex Validating a large file

To use @code{Info-validate}, visit the Info file you wish to check and
type:@refill

@example
M-x Info-validate
@end example

@noindent
Note that the @code{Info-validate} command requires an upper case
`I'.  You may also need to create a tag table before running
@code{Info-validate}.  @xref{Tagifying}.

If your file is valid, you will receive a message that says ``File appears
valid''.  However, if you have a pointer that does not point to a node,
error messages will be displayed in a buffer called @samp{*problems in
info file*}.@refill

For example, @code{Info-validate} was run on a test file that contained
only the first node of this manual.  One of the messages said:@refill

@example
In node "Overview", invalid Next: Texinfo Mode
@end example

@noindent
This meant that the node called @samp{Overview} had a `Next' pointer that
did not point to anything (which was true in this case, since the test file
had only one node in it).@refill

Now suppose we add a node named @samp{Texinfo Mode} to our test case
but we do not specify a `Previous' for this node.  Then we will get
the following error message:@refill

@example
In node "Texinfo Mode", should have Previous: Overview
@end example

@noindent
This is because every `Next' pointer should be matched by a
`Previous' (in the node where the `Next' points) which points back.@refill

@code{Info-validate} also checks that all menu entries and cross references
point to actual nodes.@refill

@code{Info-validate} requires a tag table and does not work with files
that have been split.  (The @code{texinfo-format-buffer} command
automatically splits large files.)  In order to use @code{Info-validate}
on a large file, you must run @code{texinfo-format-buffer} with an
argument so that it does not split the Info file; and you must create a
tag table for the unsplit file.

@node Unsplit
@comment  node-name,  next,  previous,  up
@subsection Creating an Unsplit File
@cindex Creating an unsplit file
@cindex Unsplit file creation

You can run @code{Info-validate} only on a single Info file that has a
tag table.  The command will not work on the indirect subfiles that
are generated when a master file is split.  If you have a large file
(longer than 300,000 bytes or so), you need to run the
@code{texinfo-format-buffer} or @code{makeinfo-buffer} command in such
a way that it does not create indirect subfiles.  You will also need
to create a tag table for the Info file.  After you have done this,
you can run @code{Info-validate} and look for badly referenced
nodes.@refill

The first step is to create an unsplit Info file.  To prevent
@code{texinfo-format-buffer} from splitting a Texinfo file into
smaller Info files, give a prefix to the @kbd{M-x
texinfo-format-buffer} command:@refill

@example
C-u M-x texinfo-format-buffer
@end example

@noindent
or else

@example
C-u C-c C-e C-b
@end example

@noindent
When you do this, Texinfo will not split the file and will not create
a tag table for it. @refill
@cindex Making a tag table manually
@cindex Tag table, making manually

@node Tagifying
@subsection Tagifying a File

After creating an unsplit Info file, you must create a tag table for
it.  Visit the Info file you wish to tagify and type:@refill

@example
M-x Info-tagify
@end example

@noindent
(Note the upper case @samp{I} in @code{Info-tagify}.)  This creates an
Info file with a tag table that you can validate.@refill

The third step is to validate the Info file:@refill

@example
M-x Info-validate
@end example

@noindent
(Note the upper case @samp{I} in @code{Info-validate}.)
In brief, the steps are:@refill

@example
@group
C-u M-x texinfo-format-buffer
M-x Info-tagify
M-x Info-validate
@end group
@end example

After you have validated the node structure, you can rerun
@code{texinfo-format-buffer} in the normal way so it will construct a
tag table and split the file automatically, or you can make the tag
table and split the file manually.@refill

@node Splitting
@comment  node-name,  next,  previous,  up
@subsection Splitting a File Manually
@cindex Splitting an Info file manually
@cindex Info file, splitting manually

You should split a large file or else let the
@code{texinfo-format-buffer} or @code{makeinfo-buffer} command do it
for you automatically.  (Generally you will let one of the formatting
commands do this job for you.  @xref{Creating an Info File}.)@refill

The split-off files are called the indirect subfiles.@refill

Info files are split to save memory.  With smaller files, Emacs does not
have make such a large buffer to hold the information.@refill

If an Info file has more than 30 nodes, you should also make a tag
table for it. @xref{Using Info-validate}, for information
about creating a tag table.  (Again, tag tables are usually created
automatically by the formatting command; you only need to create a tag
table yourself if you are doing the job manually.  Most likely, you
will do this for a large, unsplit file on which you have run
@code{Info-validate}.)@refill

@c Info-split is autoloaded in `loaddefs.el' in Emacs 18.51
@ignore
Before running @code{Info-split}, you need to load the @code{info} library
into Emacs by giving the command @kbd{M-x load-library @key{RET} info
@key{RET}}.
@end ignore

Visit the Info file you wish to tagify and split and type the two
commands:@refill

@example
M-x Info-tagify
M-x Info-split
@end example

@noindent
(Note that the @samp{I} in @samp{Info} is upper case.)@refill

When you use the @code{Info-split} command, the buffer is modified into a
(small) Info file which lists the indirect subfiles.  This file should be
saved in place of the original visited file.  The indirect subfiles are
written in the same directory the original file is in, with names generated
by appending @samp{-} and a number to the original file name.@refill

The primary file still functions as an Info file, but it contains just
the tag table and a directory of subfiles.@refill


@ignore
The simple description in the command summary seems sufficient to me
these days, so ignore this appendix.  --karl, 13mar04.

@node Refilling Paragraphs
@appendix Refilling Paragraphs
@cindex Refilling paragraphs
@cindex Filling paragraphs
@cindex Paragraphs, filling
@findex refill

The @code{@@refill} command refills and, optionally, indents the first
line of a paragraph.@footnote{Perhaps the command should have been
called the @code{@@refillandindent} command, but @code{@@refill} is
shorter and the name was chosen before indenting was possible.} The
@code{@@refill} command is no longer important, but we describe it here
because you once needed it.  You will see it in many old Texinfo
files.@refill

Without refilling, paragraphs containing long @@-constructs may look
bad after formatting because the formatter removes @@-commands and
shortens some lines more than others.  In the past, neither the
@code{texinfo-format-region} command nor the
@code{texinfo-format-buffer} command refilled paragraphs
automatically.  The @code{@@refill} command had to be written at the
end of every paragraph to cause these formatters to fill them.  (Both
@TeX{} and @code{makeinfo} have always refilled paragraphs
automatically.)  Now, all the Info formatters automatically fill and
indent those paragraphs that need to be filled and indented.@refill

The @code{@@refill} command causes @code{texinfo-format-region} and
@code{texinfo-format-buffer} to refill a paragraph in the Info file
@emph{after} all the other processing has been done.  For this reason,
you can not use @code{@@refill} with a paragraph containing either
@code{@@*} or @code{@@w@{ @dots{} @}} since the refilling action will
override those two commands.@refill

The @code{texinfo-format-region} and @code{texinfo-format-buffer}
commands now automatically append @code{@@refill} to the end of each
paragraph that should be filled.  They do not append @code{@@refill} to
the ends of paragraphs that contain @code{@@*} or @w{@code{@@w@{ @dots{}@}}}
and therefore do not refill or indent them.@refill

@end ignore


@c These are no longer ``new'', and the explanations
@c are all given elsewhere anyway, I think.  --karl, 25apr97.
@c So ignore the entire appendix.
@ignore
@c node New Features, Command and Variable Index, Obtaining TeX, Top
@c appendix Second Edition Features

@tex
% Widen the space for the first column so three control-character
% strings fit in the first column.  Switched back to default .8in
% value at end of chapter.
\global\tableindent=1.0in
@end tex

The second edition of the Texinfo manual describes more than 20 new
Texinfo mode commands and more than 50 previously undocumented Texinfo
@@-commands.  This edition is more than twice the length of the first
edition.@refill

Here is a brief description of the new commands.@refill

@c menu
* New Texinfo Mode Commands::   The updating commands are especially useful.
* New Commands::                Many newly described @@-commands.
@c end menu

@c node New Texinfo Mode Commands, New Commands, Obtaining TeX, Obtaining TeX
@c appendixsec New Texinfo Mode Commands

Texinfo mode provides commands and features especially designed for
working with Texinfo files.  More than 20 new commands have been
added, including commands for automatically creating and updating
both nodes and menus.  This is a tedious task when done by hand.@refill

The keybindings are intended to be somewhat mnemonic.@refill

@c subheading Update all nodes and menus

The @code{texinfo-master-menu} command is the primary command:

@table @kbd
@item C-c C-u m
@itemx M-x texinfo-master-menu
Create or update a master menu.
With @kbd{C-u} as a prefix argument,
first create or update all nodes
and regular menus.
@end table

@c subheading Update Pointers

@noindent
Create or update `Next', `Previous', and `Up' node pointers.@refill

@noindent
@xref{Updating Nodes and Menus}.

@table @kbd
@item C-c C-u C-n
@itemx M-x texinfo-update-node
Update a node.

@item C-c C-u C-e
@itemx M-x texinfo-every-node-update
Update every node in the buffer.
@end table

@c subheading Update Menus

@noindent
Create or update menus.@refill

@noindent
@xref{Updating Nodes and Menus}.

@table @kbd
@item C-c C-u C-m
@itemx M-x texinfo-make-menu
Make or update a menu.

@item C-c C-u C-a
@itemx M-x texinfo-all-menus-update
Make or update all the menus in a buffer.
With @kbd{C-u} as a prefix argument,
first update all the nodes.
@end table

@c subheading Insert Title as Description

@noindent
Insert a node's chapter or section title in the space for the
description in a menu entry line; position point so you can edit the
insert.  (This command works somewhat differently than the other
insertion commands, which insert only a predefined string.)@refill

@noindent
@xref{Inserting, Inserting Frequently Used Commands}.

@table @kbd
@item C-c C-c C-d
Insert title.
@end table

@c subheading Format for Info

@noindent
Provide keybindings both for the Info formatting commands that are
written in Emacs Lisp and for @code{makeinfo} that is written in
C.@refill

@noindent
@xref{Info Formatting}.

@noindent
Use the Emacs lisp @code{texinfo-format@dots{}} commands:

@table @kbd
@item C-c C-e C-r
Format the region.

@item C-c C-e C-b
Format the buffer.
@end table

@noindent
Use @code{makeinfo}:

@table @kbd
@item C-c C-m C-r
Format the region.

@item C-c C-m C-b
Format the buffer.

@item C-c C-m C-l
Recenter the @code{makeinfo} output buffer.

@item C-c C-m C-k
Kill the @code{makeinfo} formatting job.
@end table

@c subheading Typeset and Print

@noindent
Typeset and print Texinfo documents from within Emacs.

@noindent
@xref{Printing}.

@table @kbd
@item C-c C-t C-b
Run @code{texi2dvi} on the buffer.

@item C-c C-t C-r
Run @TeX{} on the region.

@item C-c C-t C-i
Run @code{texindex}.

@item C-c C-t C-p
Print the DVI file.

@item C-c C-t C-q
Show the print queue.

@item C-c C-t C-d
Delete a job from the print queue.

@item C-c C-t C-k
Kill the current @TeX{} formatting job.

@item C-c C-t C-x
Quit a currently stopped @TeX{} formatting job.

@item C-c C-t C-l
Recenter the output buffer.
@end table

@c subheading Other Updating Commands

@noindent
The ``other updating commands'' do not have standard keybindings because
they are used less frequently.@refill

@noindent
@xref{Other Updating Commands}.

@table @kbd
@item M-x texinfo-insert-node-lines
Insert missing @code{@@node} lines using
section titles as node names.

@item M-x texinfo-multiple-files-update
Update a multi-file document.
With a numeric prefix, such as @kbd{C-u 8},
update  @strong{every} pointer and
menu in @strong{all} the files and
then insert a master menu.

@item M-x texinfo-indent-menu-description
Indent descriptions in menus.

@item M-x texinfo-sequential-node-update
Insert node pointers in strict sequence.
@end table

@c no.de New Commands,  , New Texinfo Mode Commands, Obtaining TeX
@c appendix.sec New Texinfo @@-Commands

The second edition of the Texinfo manual describes more than 50
commands that were not described in the first edition.  A third or so
of these commands existed in Texinfo but were not documented in the
manual; the others are new.  Here is a listing, with brief
descriptions of them:@refill

@c subheading Indexing

@noindent
Create your own index, and merge indices.@refill

@noindent
@xref{Indices}.

@table @kbd
@item @@defindex @var{index-name}
Define a new index and its indexing command.
See also the @code{@@defcodeindex} command.

@c written verbosely to avoid overfull hbox
@item @@synindex @var{from-index} @var{into-index}
Merge the @var{from-index} index into the @var{into-index} index.
See also the @code{@@syncodeindex} command.
@end table

@c subheading Definitions

@noindent
Describe functions, variables, macros,
commands, user options, special forms, and other such artifacts in a
uniform format.@refill

@noindent
@xref{Definition Commands}.

@table @kbd
@item @@deffn @var{category} @var{name} @var{arguments}@dots{}
Format a description for functions, interactive
commands, and similar entities.

@item @@defvr, @@defop, @dots{}
15 other related commands.
@end table

@c subheading Glyphs

@noindent
Indicate the results of evaluation, expansion,
printed output, an error message, equivalence of expressions, and the
location of point.@refill

@noindent
@xref{Glyphs}.

@table @kbd
@item @@equiv@{@}
@itemx @equiv{}
Equivalence:

@item @@error@{@}
@itemx @error{}
Error message

@item @@expansion@{@}
@itemx @expansion{}
Macro expansion

@item @@point@{@}
@itemx @point{}
Position of point

@item @@print@{@}
@itemx @print{}
Printed output

@item @@result@{@}
@itemx @result{}
Result of an expression
@end table

@c subheading Page Headings

@noindent
Customize page headings.

@noindent
@xref{Headings}.

@table @kbd
@item @@headings @var{on-off-single-double}
Headings on or off, single, or double-sided.

@item @@evenfooting [@var{left}] @@| [@var{center}] @@| [@var{right}]
Footings for even-numbered (left-hand) pages.

@item @@evenheading, @@everyheading, @@oddheading, @dots{}
Five other related commands.

@item @@thischapter
Insert name of chapter and chapter number.

@item @@thischaptername, @@thisfile, @@thistitle, @@thispage
Related commands.
@end table

@c subheading Formatting

@noindent
Format blocks of text.

@noindent
@xref{Quotations and Examples}, and@*
@ref{Lists and Tables, , Making Lists and Tables}.

@table @kbd
@item @@cartouche
Draw rounded box surrounding text (no effect in Info).

@item @@enumerate @var{optional-arg}
Enumerate a list with letters or numbers.

@item @@exdent @var{line-of-text}
Remove indentation.

@item @@flushleft
Left justify.

@item @@flushright
Right justify.

@item @@format
Do not narrow nor change font.

@item @@ftable @var{formatting-command}
@itemx @@vtable @var{formatting-command}
Two-column table with indexing.

@item @@lisp
For an example of Lisp code.

@item @@smallexample
@itemx @@smalllisp
Like @@table and @@lisp, but for (originally) @@smallbook.
@end table

@c subheading Conditionals

@noindent
Conditionally format text.

@noindent
@xref{set clear value, , @code{@@set} @code{@@clear} @code{@@value}}.@refill

@table @kbd
@item @@set @var{flag} [@var{string}]
Set a flag.  Optionally, set value
of @var{flag} to @var{string}.

@item @@clear @var{flag}
Clear a flag.

@item @@value@{@var{flag}@}
Replace with value to which @var{flag} is set.

@item @@ifset @var{flag}
Format, if @var{flag} is set.

@item @@ifclear @var{flag}
Ignore, if @var{flag} is set.
@end table

@c subheading @@heading series for Titles

@noindent
Produce unnumbered headings that do not appear in a table of contents.

@noindent
@xref{Structuring}.

@table @kbd
@item @@heading @var{title}
Unnumbered section-like heading not listed
in the table of contents of a printed manual.

@item @@chapheading, @@majorheading, @@c subheading, @@subsubheading
Related commands.
@end table

@need 1000
@c subheading Font commands

@need 1000
@noindent
@xref{Smallcaps}, and @*
@ref{Fonts}.

@table @kbd
@item @@r@{@var{text}@}
Print in roman font.

@item @@sc@{@var{text}@}
Print in @sc{small caps} font.
@end table

@c subheading Miscellaneous

@noindent
See @ref{title subtitle author, , @code{@@title} @code{@@subtitle} and @code{@@author} Commands},@*
see @ref{Customized Highlighting},@*
see @ref{Overfull hboxes},@*
see @ref{Footnotes},@*
see @ref{dmn, , Format a Dimension},@*
see @ref{Raise/lower sections, , @code{@@raisesections} and @code{@@lowersections}},@*
see @ref{math, , @code{@@math}: Inserting Mathematical Expressions}.@*
see @ref{minus, , Inserting a Minus Sign},@*
see @ref{paragraphindent, , Paragraph Indenting},@*
see @ref{Cross Reference Commands},@*
see @ref{title subtitle author, , @code{@@title} @code{@@subtitle} and @code{@@author}}, and@*
see @ref{Custom Headings, , How to Make Your Own Headings}.

@table @kbd
@item @@author @var{author}
Typeset author's name.

@c @item @@definfoenclose @var{new-command}, @var{before}, @var{after},
@c Define a highlighting command for Info.  (Info only.)

@item @@finalout
Produce cleaner printed output.

@item @@footnotestyle @var{end-or-separate}
Specify footnote style, either @samp{end} or @samp{separate}.
@xref{Footnote Styles}.

@item @@dmn@{@var{dimension}@}
Format a dimension.

@item @@global@@let@var{new-cmd}=@var{existing-cmd}
Define a highlighting command for @TeX{}. (@TeX{} only.)

@item @@lowersections
Reduce hierarchical level of sectioning commands.

@item @@math@{@var{mathematical-expression}@}
Format a mathematical expression.

@item @@minus@{@}
Generate a minus sign.

@item @@paragraphindent @var{asis-or-number}
Specify paragraph indentation.

@item @@raisesections
Raise hierarchical level of sectioning commands.

@item @@ref@{@var{node-name}, @r{[}@var{entry}@r{]}, @r{[}@var{topic-or-title}@r{]}, @r{[}@var{info-file}@r{]}, @r{[}@var{manual}@r{]}@}
Make a reference.  In the printed manual, the
reference does not start with the word `see'.

@item @@title @var{title}
Typeset @var{title} in the alternative
title page format.

@item @@subtitle @var{subtitle}
Typeset @var{subtitle} in the alternative
title page format.

@item @@today@{@}
Insert the current date.
@end table
@tex
% Switch width of first column of tables back to default value
\global\tableindent=.8in
@end tex
@end ignore


@node GNU Free Documentation License
@appendix GNU Free Documentation License

@include fdl.texi


@node Command and Variable Index
@unnumbered Command and Variable Index

This is an alphabetical list of all the @@-commands, assorted Emacs Lisp
functions, and several variables.  To make the list easier to use, the
commands are listed without their preceding @samp{@@}.@refill

@printindex fn


@node General Index
@unnumbered General Index

@printindex cp


@bye
