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Texinfo

The GNU Documentation Format

for Texinfo version 6.5, 25 August 2017

Robert J. Chassell
Richard M. Stallman

This manual is for GNU Texinfo (version 6.5, 25 August 2017), a documentation system that can produce both online information and a printed manual from a single source using semantic markup.

Copyright © 1988, 1990, 1991, 1992, 1993, 1995, 1996, 1997, 1998, 1999, 2001, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 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.”


Published by the Free Software Foundation
51 Franklin St, Fifth Floor
Boston, MA 02110-1301
USA
ISBN 1-882114-67-1


Cover art by Etienne Suvasa.


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Texinfo

This manual is for GNU Texinfo (version 6.5, 25 August 2017), a documentation system that can produce both online information and a printed manual from a single source using semantic markup.

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.

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


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Texinfo Copying Conditions

GNU Texinfo is free software; this means that everyone is free to use it and free to redistribute it on certain conditions. Texinfo is not in the public domain; it is copyrighted and there are restrictions on its 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 Texinfo 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 is covered by the GNU Free Documentation License (see section GNU Free Documentation License).


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1 Overview of Texinfo

Texinfo is a documentation system that uses a single source file to produce both online information and printed output. This means that instead of writing several different documents, one for each output format, you need only write one document.

Using Texinfo, you can create a printed document (via the TeX typesetting system) in PDF or PostScript format, including chapters, sections, cross-references, and indices. From the same Texinfo source file, you can create an HTML output file suitable for use with a web browser, you can create an Info file with special features to make browsing documentation easy, and also create a Docbook file or a transliteration to XML format.

A Texinfo source file is a plain text file containing text interspersed with @-commands (words preceded by an ‘@’) that tell the Texinfo processors what to do. Texinfo’s markup commands are almost entirely semantic; that is, they specify the intended meaning of text in the document, rather than physical formatting instructions. 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. (See section Using Texinfo Mode.)

Texinfo was devised specifically for the purpose of writing software documentation and manuals. If you want to write a good manual for your program, Texinfo has many features which we hope will make your job easier. However, it provides almost no commands for controlling the final formatting. Texinfo is not intended to be a general-purpose formatting program, so if you need to lay out a newspaper, devise a glossy magazine ad, or follow the exact formatting requirements of a publishing house, Texinfo may not be the simplest tool.

Spell “Texinfo” with a capital “T” and the other letters in lowercase. The first syllable of “Texinfo” is pronounced like “speck”, not “hex”. This odd pronunciation is derived from the pronunciation of TeX. Pronounce TeX as if the ‘X’ were the last sound in the name ‘Bach’. In the word TeX, the ‘X’ is, rather than the English letter “ex”, actually the Greek letter “chi”.

Texinfo is the official documentation format of the GNU project. More information, including manuals for GNU packages, is available at the GNU documentation web page.


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1.1 Reporting Bugs

We welcome bug reports and suggestions for any aspect of the Texinfo system: programs, documentation, installation, etc. Please email them to bug-texinfo@gnu.org. You can get the latest version of Texinfo via its home page, http://www.gnu.org/software/texinfo.

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

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

It is critical to send an actual input file that reproduces the problem. What’s not critical is to “narrow down” the example to the smallest possible input—the actual input with which you discovered the bug will suffice. (Of course, if you do do experiments, the smaller the input file, the better.)

Patches are most welcome; if possible, please make them with ‘diff -c’ (see Top in Comparing and Merging Files) and include ‘ChangeLog’ entries (see Change Log in The GNU Emacs Manual), and follow the existing coding style.


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1.2 Output Formats

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

Info

(Generated via makeinfo.) Info format is mostly a plain text transliteration of the Texinfo source. It adds a few control characters to provide navigational information for cross-references, indices, and so on. The Emacs Info subsystem (see Top in Info), and the standalone info program (see Top in GNU Info), among others, can read these files. See section Info Files, and Creating and Installing Info Files.

Plain text

(Generated via makeinfo --plaintext.) This is almost the same as Info output with the navigational control characters are omitted.

HTML

(Generated via makeinfo --html.) HTML, standing for Hyper Text Markup Language, 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, both different standards and browser-specific variations. makeinfo tries to use a subset of the language that can be interpreted by any common browser, intentionally not using many newer or less widely-supported tags. Although the native output is thus rather plain, it can be customized at various levels, if desired. For details of the HTML language and much related information, see http://www.w3.org/MarkUp/. See section Generating HTML.

DVI

(Generated via texi2dvi.) The DeVIce Independent binary format is output by the TeX typesetting program (http://tug.org). This is then read by a DVI ‘driver’, which knows the actual device-specific commands that can be viewed or printed, notably Dvips for translation to PostScript (see Top in Dvips) and Xdvi for viewing on an X display (http://sourceforge.net/projects/xdvi/). See section Formatting and Printing Hardcopy. (Be aware that the Texinfo language is very different from and much stricter than TeX’s usual languages: plain TeX, LaTeX, ConTeXt, etc.)

PostScript

(Generated via texi2dvi --ps.) PostScript is a page description language that became widely used around 1985 and is still used today. http://en.wikipedia.org/wiki/PostScript gives a basic description and more preferences. By default, Texinfo uses the dvips program to convert TeX’s DVI output to PostScript. See Top in Dvips.

PDF

(Generated via texi2dvi --pdf or 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; http://en.wikipedia.org/wiki/Portable_Document_Format and http://tug.org/TUGboat/tb22-3/tb72beebe-pdf.pdf have some background. By default, Texinfo uses the pdftex program, an extension of TeX, to output PDF; see http://tug.org/applications/pdftex. See section PDF Output.

Docbook

(Generated via makeinfo --docbook.) This is an XML-based format developed some years ago, primarily for technical documentation. It therefore bears some resemblance, in broad outline, to Texinfo. See http://www.docbook.org. Various converters from Docbook to Texinfo have also been developed; see the Texinfo web pages.

XML

(Generated via makeinfo --xml.) XML is a generic syntax specification usable for any sort of content (a reference is at http://www.w3.org/XML). The makeinfo XML output, unlike all the other output formats, is a transliteration of the Texinfo source rather than processed output. That is, it translates the Texinfo markup commands into XML syntax, for further processing by XML tools. The XML contains enough information to recreate the original content, except for syntactic constructs such as Texinfo macros and conditionals. The Texinfo source distribution includes a utility script ‘txixml2texi’ to do that backward transformation.

The details of the output syntax are defined in an XML DTD as usual, which is contained in a file ‘texinfo.dtd’ included in the Texinfo source distribution and available via the Texinfo web pages. Texinfo XML files, and XML files in general, cannot be viewed in typical web browsers; they won’t follow the DTD reference and as a result will simply report a (misleading) syntax error.


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1.3 Info Files

As mentioned above, Info format is mostly a plain text transliteration of the Texinfo source, with the addition of a few control characters to separate nodes and provide navigational information, so that Info-reading programs can operate on it.

Info files are nearly always created by processing a Texinfo source document. makeinfo, also known as texi2any, is the principal command that converts a Texinfo file into an Info file; see section texi2any: The Generic Translator for Texinfo.

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 (see Top in Info).

If you want to read through an Info file in sequence, as if it were a printed manual, you can hit <SPC> repeatedly, or you get the whole file with the advanced Info command g *. (See Advanced Info commands in Info.)

The ‘dir’ file in the ‘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.

If you wish to refer to an Info file via a URI, you can use the (unofficial) syntax exemplified by the following. This works with Emacs/W3, for example:

info:emacs#Dissociated%20Press
info:///usr/info/emacs#Dissociated%20Press
info://localhost/usr/info/emacs#Dissociated%20Press

The info program itself does not follow URIs of any kind.


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1.4 Printed Books

A Texinfo file can be formatted and typeset as a printed book or manual. To do this, you need TeX, a sophisticated typesetting program written by Donald Knuth of Stanford University.

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.

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

In the United States, documents are most often printed on 8.5 inch by 11 inch pages (216mm by 280mm); this is the default size. But you can also print for 7 inch by 9.25 inch pages (178mm by 235mm, the @smallbook size; or on A4 or A5 size paper (@afourpaper, @afivepaper). See section @smallbook: Printing “Small” Books, and Printing on A4 Paper.

TeX is freely distributable. It is written in a superset of Pascal for literate programming called WEB and can be compiled either in Pascal or (by using a conversion program that comes with the TeX distribution) in C.

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.

See section Obtaining TeX, for information on acquiring TeX. It is not part of the Texinfo distribution.


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1.5 Adding Output Formats

The output formats in the previous sections handle a wide variety of usage, but of course there is always room for more.

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. The way to do this that would be most useful is to write a new back-end for texi2any, our reference implementation of a Texinfo parser; it creates a tree representation of the Texinfo input that you can use for the conversion. The documentation in the source file ‘tp/Texinfo/Convert/Converter.pm’ is a good place to start. See section texi2any: The Generic Translator for Texinfo.

Another viable approach is use the Texinfo XML output from texi2any as your input. This XML is an essentially complete representation of the input, but without the Texinfo syntax and option peculiarities, as described above.

If you still cannot resist the temptation of writing a new program that reads Texinfo source directly, let us give some more caveats: please do not underestimate the amount of work required. Texinfo is by no means a simple language to parse correctly, and remains under development, so you would be committing to an ongoing task. You are advised to check that the tests of the language that come with texi2any give correct results with your new program.

From time to time, proposals are made to generate traditional Unix man pages from Texinfo source. However, because man pages have a strict conventional format, creating a good man page requires a completely different source from that needed for 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 write the man page directly.

As an alternative way to support man pages, you may find the program help2man to be useful. It generates a traditional man page from the ‘--help’ output of a program. In fact, the man pages for the programs in the Texinfo distribution are generated with this. It is GNU software written by Brendan O’Dea, available from http://www.gnu.org/software/help2man.


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1.6 History

Richard M. Stallman invented the Texinfo format, wrote the initial processors, and created Edition 1.0 of this manual. Robert 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 originally wrote the standalone makeinfo and info programs. Karl Berry has continued maintenance since Texinfo 3.8 (manual edition 2.22).

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. François Pinard and David D. Zuhn, tirelessly recorded and reported mistakes and obscurities. Zack Weinberg did the impossible by implementing the macro syntax in ‘texinfo.tex’. Thanks 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 ‘ChangeLog’ file. Our mistakes are our own.

Beginnings

In the 1970’s at CMU, Brian Reid developed a program and format named Scribe to mark up documents for printing. It used the @ 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.

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

BoTeX 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 BoTeX. He also developed a nifty on-line help format called Info, and then combined BoTeX and Info to create Texinfo, a mark up language for text that is intended to be read both online and as printed hard copy.

Moving forward, the original translator to create Info was written (primarily by RMS and Bob Chassell) in Emacs Lisp, namely the texinfo-format-buffer and other functions. In the early 1990s, Brian Fox reimplemented the conversion program in C, now called makeinfo.

Reimplementing in Perl

In 2012, the C makeinfo was itself replaced by a Perl implementation generically called texi2any. This version supports the same level of output customization as texi2html, an independent program originally written by Lionel Cons, later with substantial work by many others. The many additional features needed to make texi2html a replacement for makeinfo were implemented by Patrice Dumas. The first never-released version of texi2any was based on the texi2html code. That implementation, however, was abandoned in favor of the current program, which parses the Texinfo input into a tree for processing. It still supports nearly all the features of texi2html.

The new Perl program is much slower than the old C program. We hope the speed gap will close in the future, but it may not ever be entirely comparable. So why did we switch? In short, we intend and hope that the present program will be much easier than the previous C implementation of makeinfo to extend to different output styles, back-end output formats, and all other customizations. In more detail:

See section texi2any: A Texinfo Reference Implementation, for more on the rationale for and role of texi2any.


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2 Writing a Texinfo File

This chapter describes Texinfo syntax and what is required in a Texinfo file, and gives a short sample file.


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2.1 General Syntactic Conventions

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


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2.2 Comments

You can write comments in a Texinfo file by using the @comment command, which may be abbreviated to @c. Such comments are for a person looking at the Texinfo source file. All the text on a line that follows either @comment or @c is a comment; the rest of the line does not appear in the visible output. (To be precise, the character after the @c or @comment must be something other than a dash or alphanumeric, or it will be taken as part of the command.)

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

In cases of nested command invocations, complicated macro definitions, etc., @c and @comment may provoke an error when processing with TeX. Therefore, you can also use the DEL character (ASCII 127 decimal, 0x7f hex, 0177 octal) as a true TeX comment character (catcode 14, in TeX internals). Everything on the line after the DEL will be ignored.

You can also have long stretches of text ignored by the Texinfo processors with the @ignore and @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 @ignore and @end ignore for writing comments. (For some caveats regarding nesting of such commands, see section Conditional Nesting.)


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2.3 What a Texinfo File Must Have

By convention, the name of a Texinfo file ends with one of the extensions ‘.texinfo’, ‘.texi’, ‘.txi’, or ‘.tex’.(2)

In order to be made into a printed manual and other output formats, a Texinfo file must begin with lines like this:

\input texinfo
@settitle name-of-manual

The contents of the file follow this beginning, and then you must end the Texinfo source with a line like this:

@bye

Here’s an explanation:

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 two lines at the beginning and the one line at the end.


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2.4 A Short Sample Texinfo File

Here is a short but complete Texinfo file, so you can see how Texinfo source appears in practice. The first three parts of the file are mostly boilerplate: when writing a manual, you simply change the names as appropriate.

The complete file, without interspersed comments, is shown in Short Sample.

See section Beginning and Ending a Texinfo File, for more documentation on the commands listed here.

Header

The header tells TeX which definitions file to use, names the manual, and carries out other such housekeeping tasks.

\input texinfo
@settitle Sample Manual 1.0

Summary Description and Copyright

This segment describes the document and contains the copyright notice and copying permissions. This is done with the @copying command.

A real manual includes more text here, according to the license under which it is distributed. See section GNU Sample Texts.

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

Copyright @copyright{} 2016 Free Software Foundation, Inc.
@end copying

Titlepage, Copyright, Contents

The title and copyright segment contains the title and copyright pages for the printed manual. The segment must be enclosed between @titlepage and @end titlepage commands. The title and copyright page does not appear in the online output.

We use the @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 @contents command generates a table of contents.

@titlepage
@title Sample Title
@c The following two commands start the copyright page.
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage
@c Output the table of contents at the beginning.
@contents

‘Top’ Node and Master Menu

The ‘Top’ node starts off the online output; it does not appear in the printed manual. We repeat the short description from the beginning of the ‘@copying’ text, but there’s no need to repeat the copyright information, so we don’t use ‘@insertcopying’ here.

The ‘@top’ command itself helps makeinfo determine the relationships between nodes. The ‘Top’ node contains at least a top-level menu listing the chapters, and possibly a Master Menu listing all the nodes in the entire document.

@ifnottex
@node Top
@top Short Sample

This is a short sample Texinfo file.
@end ifnottex

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

The Body of the Document

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.

@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

The End of the Document

This may contain commands for printing indices, and closes with the @bye command, which marks the end of the document.

@node Index
@unnumbered Index
@printindex cp

@bye

Some Results

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


This is the first chapter.

Here is a numbered list.

  1. This is the first item.
  2. This is the second item.

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3 Beginning and Ending a Texinfo File

This chapter expands on the minimal complete Texinfo source file previously given (see section A Short Sample Texinfo File).

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

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


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3.1 Sample Texinfo File Beginning

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.

See section GNU Sample Texts, for the full texts to be used in GNU manuals.

\input texinfo
@settitle name-of-manual version

@copying
This manual is for program, version version.

Copyright @copyright{} years copyright-owner.

@quotation
Permission is granted to …
@end quotation
@end copying
@titlepage
@title name-of-manual-when-printed
@subtitle subtitle-if-any
@subtitle second-subtitle
@author author
@c  The following two commands
@c  start the copyright page.
@page
@vskip 0pt plus 1filll
@insertcopying
Published by …
@end titlepage

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

@ifnottex
@node Top
@top title

This manual is for program, version version.
@end ifnottex

@menu
* First Chapter::    Getting started …
* Second Chapter::          …
 …
* Copying::          Your rights and freedoms.
@end menu
@node First Chapter
@chapter First Chapter

@cindex first chapter
@cindex chapter, first
…

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3.2 Texinfo File Header

Texinfo files start with at least two lines. These are the \input texinfo line and the @settitle line.

Also, if you want to format just part of the Texinfo file in Emacs, you must write the @settitle line between start-of-header and end-of-header lines. These 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. @synindex (see section @synindex: Combining indices), for instance, is another command often included in the header.

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

\input texinfo
@settitle Sample Manual 1.0

(See section GNU Sample Texts for complete sample texts.)


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3.2.1 The First Line 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:

\input texinfo

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

You may optionally follow this line with a comment to tell GNU Emacs to use Texinfo mode when the file is edited:

\input texinfo   @c -*-texinfo-*-

This may be useful when Emacs doesn’t detect the file type from the file extension automatically.


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3.2.2 Start of Header

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

@c %**start of header

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

The start- and end-of-header lines allow you to format only part of a Texinfo file for Info or printing. See section The texinfo-format… Commands.

The odd string of characters, ‘%**’, 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 tex-start-of-header and/or tex-end-of-header Emacs variables. See section Formatting and Printing in Texinfo Mode.


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3.2.3 @setfilename: Set the Output File Name

The @setfilename line specifies the name of the output file to be generated. When present, it should be the first Texinfo command (that is, after ‘\input texinfo’). Write the @setfilename command at the beginning of a line and follow it on the same line by the Info file name.

@setfilename info-file-name

The 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 ‘.texi’) entirely from the input file name, or (recommended) replace it with the ‘.info’ extension.

When a @setfilename line is present, the Texinfo processors ignore everything written before the @setfilename line. This is why the very first line of the file (the \input line) does not show up in the output.

If there is no @setfilename line, makeinfo uses the input file name to determine the output name: first, any of the extensions .texi, .tex, .txi or .texinfo is removed from the input file name; then, the output format specific extension is added—.html when generating HTML, .info when generating Info, etc. The \input line is still ignored in this processing, as well as leading blank lines.

When producing another output format, makeinfo will replace any final extension with the output format-specific extension (‘html’ when generating HTML, for example), or add a dot followed by the extension (‘.html’ for HTML) if the given name has no extension.

@setfilename used to be required by the Texinfo processors, and some other programs may still expect it to be present; for example, Automake (see Texinfo in GNU Automake).

Although an explicit ‘.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 ‘-1’, ‘-2’, …, ‘-10’, ‘-11’, and so on, to the original file name. (See section Tag Files and Split Files.) The subfile name ‘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 ‘texinfo’ rather than ‘texinfo.info’. When 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 ‘texin-10’, ‘gcc.i12’, etc.

See also the ‘--output’ option in Invoking texi2any/makeinfo from a Shell.


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3.2.4 @settitle: Set the Document Title

A Texinfo file should contain a line that looks like this:

@settitle title

Write the @settitle command at the beginning of a line and follow it on the same line by the title. Do not write anything else on the line. The @settitle command should precede everything that generates actual output. The best place for it is right after the @setfilename command (described in the previous section).

This command tells TeX the title to use in a header or footer for double-sided output, in case such headings are output. For more on headings for TeX, see Heading Generation.

In the HTML file produced by makeinfo, title serves as the document ‘<title>’. It also becomes the default document description in the ‘<head>’ part (see section @documentdescription: Summary Text).

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


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3.2.5 End of Header

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

@c %**end of header

See section Start of Header.


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3.3 Document 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 (@copying) to declare this text once, and another command (@insertcopying) to insert the text at appropriate points.

This section is about the license of the Texinfo document. If the document is a software manual, the software is typically under a different license—for GNU and many other free software packages, software is usually released under the GNU GPL, and manuals are released under the GNU FDL. It is helpful to state the license of the software of the manual, but giving the complete text of the software license is not necessarily required.


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3.3.1 @copying: Declare Copying Permissions

The @copying command should be given very early in the document; the recommended location is right after the header material (see section 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:

@copying
This manual is for program (version version, updated
date), which …

Copyright @copyright{} years copyright-owner.

@quotation
Permission is granted to …
@end quotation
@end copying

The @quotation has no legal significance; it’s there to improve readability in some contexts.

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

The @copyright{} command generates a ‘c’ inside a circle when the output format supports this glyph (print and HTML always do, for instance). When the glyph is not supported in the output, it generates the three-character sequence ‘(C)’.

The copyright notice itself has the following legally-prescribed form:

Copyright © years copyright-owner.

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.

The list of years should include all years in which a version was completed (even if it was released in a subsequent year). It is simplest for each year to be written out individually and in full, separated by commas.

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 @copying block) in the source file.

See Copyright Notices in GNU Maintainer Information, for additional information. See section GNU Sample Texts, for the full text to be used in GNU manuals. See section GNU Free Documentation License, for the license itself under which GNU and other free manuals are distributed.


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3.3.2 @insertcopying: Include Permissions Text

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

@insertcopying

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

The @copying command itself causes the permissions text to appear in an Info file 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 not see this text (except when using the advanced Info command g *), but this does not matter for legal purposes, because the text is present.

Similarly, the @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 @copying also appears automatically at the beginning of the XML and Docbook output files.


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3.4 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 printed manuals, but not in most other output formats. Because of this, it is possible to use several slightly obscure typesetting commands that are not to be used in the main text. In addition, this part of the beginning of a Texinfo file contains the text of the copying permissions that appears in the printed manual.


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3.4.1 @titlepage

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

The @end titlepage command starts a new page and turns on page numbering (see section Heading Generation). All the material that you want to appear on unnumbered pages should be put between the @titlepage and @end titlepage commands. You can force the table of contents to appear there with the @setcontentsaftertitlepage command (see section Generating a Table of Contents).

By using the @page command you can force a page break within the region delineated by the @titlepage and @end titlepage commands and thereby create more than one unnumbered page. This is how the copyright page is produced. (The @titlepage command might perhaps have been better named the @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(3) 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 The ‘Top’ Node and Master Menu.)

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

The second method uses the @title, @subtitle, and @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.

For sufficiently simple documents, and for the bastard title page in traditional book frontmatter, Texinfo also provides a command @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.


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3.4.2 @titlefont, @center, and @sp

You can use the @titlefont, @sp, and @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 @titlefont command to select a large font suitable for the title itself. You can use @titlefont more than once if you have an especially long title.

For HTML output, each @titlefont command produces an <h1> heading, but the HTML document <title> is not affected. For that, you must put a @settitle command before the @titlefont command (see section @settitle: Set the Document Title).

For example:

@titlefont{Texinfo}

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

@center @titlefont{Texinfo}

centers the title, which in this example is “Texinfo” printed in the title font.

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

@sp 2

This inserts two blank lines on the printed page. (See section @sp n: Insert Blank Lines, for more information about the @sp command.)

A template for this method looks like this:

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

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.


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3.4.3 @title, @subtitle, and @author

You can use the @title, @subtitle, and @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 @sp command is needed to adjust vertical spacing.

Write the @title, @subtitle, or @author commands at the beginning of a line followed by the title, subtitle, or author. The @author command may be used for a quotation in an @quotation block (see section @quotation: Block Quotations); except for that, it is an error to use any of these commands outside of @titlepage.

The @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. The title must be given on a single line in the source file; it will be broken into multiple lines of output is needed.

For long titles, the @* command may be used to specify the line breaks in long titles if the automatic breaks do not suit. Such explicit line breaks are generally reflected in all output formats; if you only want to specify them for the printed output, use a conditional (see section Conditionally Visible Text). For example:

@title This Long Title@inlinefmt{tex,@*} Is Broken in @TeX{}

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

The @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 followed by a black rule that is thinner than the rule that underlines the title.

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

@author by Jane Smith and John Doe

or you can write the names one above each other by using multiple @author commands:

@author Jane Smith
@author John Doe

A template for this method looks like this:

@titlepage
@title name-of-manual-when-printed
@subtitle subtitle-if-any
@subtitle second-subtitle
@author author
@page
…
@end titlepage

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3.4.4 Copyright Page

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 @titlepage and @end titlepage commands.

Use the @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 @page:

@vskip 0pt plus 1filll

The @vskip command inserts whitespace in the TeX output; it is ignored in all other output formats. The ‘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 ‘l’s in the word ‘filll’; this is correct.

To insert the copyright text itself, write @insertcopying next (see section Document Permissions):

@insertcopying

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

Here is an example putting all this together:

@titlepage
…
@page
@vskip 0pt plus 1filll
@insertcopying

Published by …

Cover art by …
@end titlepage

We have one more special case to consider: for plain text output, you must insert the copyright information explicitly if you want it to appear. For instance, you could have the following after the copyright page:

@ifplaintext
@insertcopying
@end ifplaintext

You could include other title-like information for the plain text output in the same place.


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3.4.5 Heading Generation

Like all @end commands (see section Quotations and Examples), the @end titlepage command must be written at the beginning of a line by itself, with only one space between the @end and the 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.

Texinfo has two standard page heading formats, one for documents printed on one side of each sheet of paper (single-sided printing), and the other for documents printed on both sides of each sheet (double-sided printing).

In full generality, you can control the headings in different ways:


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3.5 Generating a Table of Contents

The @chapter, @section, and other structuring commands (see section Chapter 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 @contents and/or @summarycontents command(s).

@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 @majorheading, @chapheading, and the other @…heading commands do not appear in the table of contents (see section Structuring Command Types).

@shortcontents
@summarycontents

(@summarycontents is a synonym for @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.

Both contents commands should be written on a line by themselves, and placed near the beginning of the file, after the @end titlepage (see section @titlepage), before any sectioning command. 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 @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 makeinfo --plaintext) and in other output formats, such as HTML.

When 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.


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3.6 The ‘Top’ Node and Master Menu

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.

It is conventional and desirable to write a @top sectioning command line containing the title of the document immediately after the @node Top line (see section The @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 @ifnottex and @end ifnottex commands. (TeX does not print either an @node line or a menu; they appear only in Info; strictly speaking, you are not required to enclose these parts between @ifnottex and @end ifnottex, but it is simplest to do so. See section Conditionally Visible Text.)


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3.6.1 Top Node Example

Here is an example of a Top node.

@ifnottex
@node Top
@top Sample Title

This is the text of the top node.
@end ifnottex
Additional general information.

@menu
* First Chapter::
* Second Chapter::
…
* Index::
@end menu

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3.6.2 Parts of a Master Menu

A master menu is the main menu. It is customary to include a detailed menu listing all the nodes in the document in this menu.

Like any other menu, a master menu is enclosed in @menu and @end menu and does not appear in the printed output.

Generally, a master menu is divided into parts.

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. (See section Writing a Menu, for more information.)

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

@menu
* Copying Conditions::  Your rights.
* Overview::            Texinfo in brief.
…
* Command and Variable Index::
* General Index::
@detailmenu
--- The Detailed Node Listing ---

Overview of Texinfo

* Reporting Bugs:: …
…
Beginning a Texinfo File

* Sample Beginning:: …
…
@end detailmenu
@end menu

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3.7 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.


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3.7.1 @documentdescription: Summary Text

When producing HTML output for a document, makeinfo writes a ‘<meta>’ element in the ‘<head>’ to give some idea of the content of the document. By default, this description is the title of the document, taken from the @settitle command (see section @settitle: Set the Document Title). To change this, use the @documentdescription environment, as in:

@documentdescription
descriptive text.
@end documentdescription

This will produce the following output in the ‘<head>’ of the HTML:

<meta name=description content="descriptive text.">

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


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3.7.2 @setchapternewpage: Blank Pages Before Chapters

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 @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 @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:

@setchapternewpage odd

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

@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.

@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.

@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.

Texinfo does not have a @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 @setchapternewpage sets, you can explicit control them with the @headings command. See section The @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.

The @setchapternewpage has no effect in output formats that do not have pages, such as Info and HTML.

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


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3.7.3 The @headings Command

The @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 @setchapternewpage command. You need the @headings command only if the @setchapternewpage command does not do what you want, or if you want to turn off predefined page headings prior to defining your own. Write a @headings command immediately after the @end titlepage command.

You can use @headings as follows:

@headings off

Turn off printing of page headings.

@headings single

Turn on page headings appropriate for single-sided printing.

@headings double

Turn on page headings appropriate for double-sided printing.

@headings singleafter
@headings doubleafter

Turn on single or double headings, respectively, after the current page is output.

@headings on

Turn on page headings: single if ‘@setchapternewpage on’, double otherwise.

For example, suppose you write @setchapternewpage off before the @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 @headings double after the @end titlepage command.

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

@end titlepage
@headings off

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

You can also specify your own style of page heading and footing. See section Page Headings, for more information.


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3.7.4 @paragraphindent: Controlling Paragraph Indentation

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

@paragraphindent indent

The indentation is according to the value of indent:

asis

Do not change the existing indentation (not implemented in TeX).

none
0

Omit all indentation.

n

Indent by n space characters in Info output, by n ems in TeX.

The default value of indent is 3. @paragraphindent is ignored for HTML output.

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


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3.7.5 @firstparagraphindent: Indenting After Headings

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 @firstparagraphindent command:

@firstparagraphindent word

The first paragraph after a heading is indented according to the value of word:

none

Prevents the first paragraph from being indented (default). This option is ignored by makeinfo if @paragraphindent asis is in effect.

insert

Include normal paragraph indentation. This respects the paragraph indentation set by a @paragraphindent command (see section @paragraphindent: Controlling Paragraph Indentation).

@firstparagraphindent is ignored for HTML and Docbook output.

It is best to write the @firstparagraphindent command before the end-of-header line at the beginning of a Texinfo file, so the region formatting commands indent paragraphs as specified. See section Start of Header.


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3.7.6 @exampleindent: Environment Indenting

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

@exampleindent indent

The indentation is according to the value of indent:

asis

Do not change the existing indentation (not implemented in TeX).

0

Omit all indentation.

n

Indent environments by n space characters in Info output, by n ems in TeX.

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

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


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3.8 Ending a Texinfo File

The end of a Texinfo file should include commands to create indices (see section Printing Indices and Menus), and the @bye command to mark the last line to be processed. For example:

@node Index
@unnumbered Index

@printindex cp

@bye

An @bye command terminates Texinfo processing. None of the formatters process anything following @bye; any such text is completely ignored. The @bye command should be on a line by itself.

Thus, if you wish, you may follow the @bye line with arbitrary notes. Also, you may follow the @bye line with a local variables list for Emacs, most typically a ‘compile-command’ (see section Using the Local Variables List).


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4 Nodes

A node is a region of text that begins at a @node command, and continues until the next @node command. To specify a node, write a @node command at the beginning of a line, and follow it with the name of the node. Each node contains the discussion of one topic. Info readers display one node at a time, and provide commands for the user to move to related nodes. The HTML output can be similarly navigated.

Nodes are used as the targets of cross-references. Cross-references, such as the one at the end of this sentence, are made with @xref and related commands; see Cross-references. Cross-references can be sprinkled throughout the text, and provide a way to represent links that do not fit a hierarchical structure.

Normally, you put a node command immediately before each chapter structuring command—for example, an @section or @subsection line. (See section Chapter Structuring.). You must do this even if you do not intend to format the file for Info. This is because TeX uses both @node names and chapter-structuring names in the output for cross-references. The only time you are likely to use the chapter structuring commands without also using nodes is if you are writing a document that contains no cross references and will only be printed, not transformed into Info, HTML, or other formats.


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4.1 Texinfo Document Structure

Nodes can contain menus, which contain the names of child nodes within the parent node; for example, a node corresponding to a chapter would have a menu of the sections in that chapter. The menus allow the user to move to the child nodes in a natural way in the online output.

In addition, nodes contain node pointers that name other nodes. The ‘Next’ and ‘Previous’ pointers form nodes at the same sectioning level into a chain. As you might imagine, the ‘Next’ pointer links to the next node, and the ‘Previous’ pointer links to the previous node. Thus, for example, all the nodes that are at the level of sections within a chapter are linked together, and the order in this chain is the same as the order of the children in the menu of the parent chapter. Each child node records the parent node name as its ‘Up’ pointer.

The Info and HTML output from makeinfo for each node includes links to the ‘Next’, ‘Previous’, and ‘Up’ nodes. The HTML also uses the accesskey attribute with the values ‘n’, ‘p’, and ‘u’ respectively. This allows people using web browsers to follow the navigation using (typically) M-letter, e.g., M-n for the ‘Next’ node, from anywhere within the node. Node pointers and menus provide structure for Info files just as chapters, sections, subsections, and the like provide structure for printed books. The two structures are theoretically distinct; in practice, however, the tree structure of printed books is essentially always used for the node and menu structure also, as this leads to a document which is easiest to follow. See section Texinfo Document Structure.

Typically, the sectioning structure and the node structure are completely parallel, with one node for each chapter, section, etc., and with the nodes following the same hierarchical arrangement as the sectioning. Thus, if a node is at the logical level of a chapter, its child nodes are at the level of sections; similarly, the child nodes of sections are at the level of subsections.

Although it is technically possible to create Texinfo documents with only one structure or the other, or for the two structures not to be parallel, or for either the sectioning or node structure to be abnormally formed, etc., this is not at all recommended. To the best of our knowledge, all the Texinfo manuals currently in general use do follow the conventional parallel structure.


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4.2 Choosing Node Names

The name of a node identifies the node. For all the details of node names, see section @node Line Requirements).

Here are some suggestions for node names:

Because node names are used in cross-references, it is not desirable to casually change them once published. Such name changes invalidate references from other manuals, from mail archives, and so on. See section HTML Cross-reference Link Preservation: manual-noderename.cnf.

The pointers from a given node enable you to reach other nodes and consist simply of the names of those nodes. The pointers are usually not specified explicitly, as makeinfo can determine them (see section makeinfo Pointer Creation).

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 pointers name the same node.

Usually, the first node of a Texinfo file is the ‘Top’ node, and its ‘Up’ pointer points to the ‘dir’ file, which contains the main menu for all of Info.


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4.3 Writing an @node Line

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

@node node-name

After you have inserted an @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.

If you wish, you can ignore @node lines altogether in your first draft and then use the texinfo-insert-node-lines command to create @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. Useful cross-references are an especially important feature of a good Texinfo manual.

Even when you explicitly specify all pointers, you cannot write the nodes in the Texinfo source file in an arbitrary order! Because formatters must process the file sequentially, irrespective of node pointers, you must write the nodes in the order you wish them to appear in the output. For Info format one can imagine that the order may not matter, but it matters for the other formats.

You may optionally follow the node name argument to @node with up to three optional arguments on the rest of the same line, separating the arguments with commas. These are the names of the ‘Next’, ‘Previous’, and ‘Up’ pointers, in that order. We recommend omitting them if your Texinfo document is hierarchically organized, as virtually all are (see section makeinfo Pointer Creation).

Any spaces before or after each name on the @node line are ignored.

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

@node node-name, next, previous, up

The 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: ‘@node mynode,,,uppernode’. However, we recommend leaving off all the pointers and letting makeinfo determine them.

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 (recommended), you can leave the pointers out of the Texinfo file and let makeinfo insert node pointers into the Info file it creates. (See section Using Texinfo Mode, and 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 C-c C-c n. This command inserts ‘@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.


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4.4 @node Line Requirements

Names used with @node have several requirements:


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4.5 The First Node

The first node of a Texinfo file is the Top node, except in an included file (see section Include Files). The Top node should contain a short summary, copying permissions, and a master menu. See section The ‘Top’ Node and Master Menu, 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:

See section Installing an Info File, for more information about installing an Info file in the ‘info’ directory.

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

@node Top

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4.6 The @top Sectioning Command

The @top command is a special sectioning command that you should only use after a ‘@node Top’ line at the beginning of a Texinfo file. The @top command tells the makeinfo formatter which node is to be used as the root of the node tree.

It produces the same sort of output as @unnumbered (see section @unnumbered, @appendix: Chapters with Other Labeling).

The @top node is conventionally wrapped in an @ifnottex conditional so that it will not appear in TeX output (see section Conditionally Visible Text). Thus, in practice, a Top node usually looks like this:

@ifnottex
@node Top
@top your-manual-title

very-high-level-summary
@end ifnottex

@top is ignored when raising or lowering sections. That is, it is never lowered and nothing can be raised to it (see section Raise/lower Sections: @raisesections and @lowersections).


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4.7 Node and Menu Illustration

Here is a diagram that illustrates a Texinfo file with three chapters, each of which contains two sections.

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.

                         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

Using explicit pointers (not recommended, but for shown for purposes of the example), the fully-written command to start Chapter 2 would be this:

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

This @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 (and should) omit writing out these node names if your document is hierarchically organized (see section makeinfo Pointer Creation), but the pointer relationships still obtain.

Note: ‘Next’ and ‘Previous’ refer to nodes 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. (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.)

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

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

Using explicit pointers, the node for Sect. 2.1 is written like this:

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

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 Cross-references.)

A @node command and a chapter structuring command are conventionally used together, in that order, often followed by indexing commands. (As shown in the example above, you may follow the @node line with a comment line, e.g., to show which pointer is which if explicit pointers are used.) The Texinfo processors use this construct to determine the relationships between nodes and sectioning commands.

Here is the beginning of the chapter in this manual called “Ending a Texinfo File”. This shows an @node line followed by an @chapter line, and then by indexing lines.

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

An earlier version of the manual used explicit node pointers. Here is the beginning of the same chapter for that case. This shows an @node line followed by a comment line, a @chapter line, and then by indexing lines.

@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
…

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4.8 makeinfo Pointer Creation

The makeinfo program can automatically determine node pointers for a hierarchically organized document. This implicit node pointer creation feature in makeinfo relieves you from the need to update menus and pointers manually or with Texinfo mode commands. (See section Updating Nodes and Menus.) We highly recommend taking advantage of this.

To do so, write your @node lines with just the name of the node:

@node My Node

You do not need to write out the ‘Next’, ‘Previous’, and ‘Up’ pointers.

Then, you must write a sectioning command, such as @chapter or @section, on the line immediately following each truncated @node line (except that comment lines may intervene). This is where it normally goes.

Also, 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 level.

Finally, you must follow the ‘Top’ @node line with a line beginning with @top to mark the top-level node in the file. See section The @top Sectioning Command.

If you use a detailed menu in your master menu (see section Parts of a Master Menu), mark it with the @detailmenu … @end detailmenu environment, or makeinfo will get confused, typically about the last and/or first node in the document.

In most cases, you will want to take advantage of this feature and not redundantly specify node pointers that the programs can determine. 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), so node pointers may still be specified explicitly, in full generality.


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4.9 Menus

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.


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4.9.1 Writing a Menu

A menu consists of a @menu command on a line by itself, followed by menu entry lines or menu comment lines, and then followed by an @end menu command on a line by itself.

A menu looks like this:

@menu
Larger Units of Text

* Files::                       All about handling files.
* Multiples: Buffers.           Multiple buffers; editing
                                 several files at once.
@end menu

In a menu, every line that begins with an ‘’ is a menu entry. (Note the space after the asterisk.)

A line that does not start with an ‘’ may also appear in a menu. Such a line is not a menu entry but rather a menu comment line that appears in the Info file. In the example above, the line ‘Larger Units of Text’ is such a menu comment line; the two lines starting with ‘’ are menu entries.

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 making use of this, because it is hard for readers to follow. Also, the makeinfo implicit pointer creation feature (see section makeinfo Pointer Creation) and GNU Emacs Texinfo mode updating commands work only to create menus of subordinate nodes in a hierarchically structured document. It is much better to use cross-references to refer to arbitrary nodes.

makeinfo can automatically generate menus in nodes for Info and HTML output, based on the chapter structure of the document. To specify that you want it to do this, place the line ‘@validatemenus off’ near the beginning of the document.

In Info, a user selects a node with the m (Info-menu) command. The menu entry name is what the user types after the m command. In the HTML output from makeinfo, the accesskey attribute is used with the values ‘1’…‘9’ for the first nine entries. This allows people using web browsers to follow the first menu entries using (typically) M-digit, e.g., M-1 for the first entry.


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4.9.2 A Menu Example

A menu looks like this in Texinfo:

@menu
* menu entry name: Node name.   A short description.
* Node name::                   This form is preferred.
@end menu

This produces:

* menu:

* menu entry name: Node name.   A short description.
* Node name::                   This form is preferred.

Here is an example as you might see it in a Texinfo file:

@menu
Larger Units of Text

* Files::                       All about handling files.
* Multiples: Buffers.           Multiple buffers; editing
                                 several files at once.
@end menu

This produces:

* menu:
Larger Units of Text

* Files::                       All about handling files.
* Multiples: Buffers.           Multiple buffers; editing
                                 several files at once.

In this example, the menu has two entries. ‘Files’ is both a menu entry name and the name of the node referred to by that name. ‘Multiples’ is the menu entry name; it refers to the node named ‘Buffers’. The line ‘Larger Units of Text’ is a comment; it appears in the menu, but is not an entry.

Since no file name is specified with either ‘Files’ or ‘Buffers’, they must be the names of nodes in the same Info file (see section Referring to Other Info Files).


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4.9.3 Menu Location

There may be at most one menu in a node. A menu is conventionally located at the end of a node, without any regular text or additional commands between the @end menu and the beginning of the next node.

This convention is useful, since a reader who uses the menu could easily miss any such text. Also, any such post-menu text will be considered part of the menu in Info output (which has no marker for the end of a menu). Thus, a line beginning with ‘* ’ will likely be incorrectly handled.

It’s usually best if a node with a menu does not contain much text. If you find yourself with a lot of text before a menu, we generally recommend moving all but a couple of paragraphs into a new subnode. Otherwise, it is easy for readers to miss the menu.


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4.9.4 The Parts of a Menu

A menu entry has three parts, only the second of which is required:

  1. The menu entry name (optional).
  2. The name of the node (required).
  3. A description of the item (optional).

The template for a generic menu entry looks like this (but see the next section for one more possibility):

* menu-entry-name: node-name.   description

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 (‘. ’).

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 multiple 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. An empty line, or the next menu entry, ends a description.

Space characters in a menu are preserved as-is in the Info output; this allows you to format the menu as you wish. Unfortunately you must type node names without any extra spaces or some versions of some Info readers will not find the node (see section @node Line Requirements).

makeinfo warns when the text of a menu item (and node names and cross-references) contains a problematic construct that will interfere with its parsing in Info. If you don’t want to see the warnings, you can set the customization variable INFO_SPECIAL_CHARS_WARNING to ‘0’ (see section Other Customization Variables).


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4.9.5 Less Cluttered 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.

For example, write

* Name::                        description

instead of

* Name: Name.                   description

We recommend using the node name for the menu entry name whenever possible, since it reduces visual clutter in the menu.


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4.9.6 Referring to Other Info Files

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. Some examples:

@menu
* first-entry-name:(filename)nodename.     description
* (filename)second-node::                  description
@end menu

For example, to refer directly to the ‘Outlining’ and ‘Rebinding’ nodes in the Emacs Manual, you could write a menu like this:

@menu
* Outlining: (emacs)Outline Mode. The major mode for
                                   editing outlines.
* (emacs)Rebinding::              How to redefine the
                                   meaning of a key.
@end menu

If you do not list the node name, but only name the file, then Info presumes that you are referring to the ‘Top’ node. Examples:

* Info: (info).         Documentation browsing system.
* (emacs)::             The extensible, self-documenting
                         text editor.

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.


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5 Chapter Structuring

Texinfo’s chapter structuring commands divide a document into a hierarchy of chapters, sections, subsections, and subsubsections. These commands generate large headings in the text, like the one above. They also provide information for generating the table of contents (see section Generating a Table of Contents).

Normally you put a @node command immediately before each chapter structuring command. See section Nodes.


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5.1 Tree Structure of Sections

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.

Here is a diagram that shows a Texinfo file with three chapters, each with two sections.

                         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

In a Texinfo file that has this structure, the beginning of Chapter 2 would be written like this:

@node    Chapter 2
@chapter Chapter 2

For purposes of example, here is how it would be written with explicit node pointers:

@node    Chapter 2,  Chapter 3, Chapter 1, Top
@chapter Chapter 2

The chapter structuring commands are described in the sections that follow; the @node command is described in the previous chapter (see section Nodes).


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5.2 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.

The four groups of commands are the @chapter series, the @unnumbered series, the @appendix series, and the @heading series. Each command produces a title with a different appearance in the body of the document. Some of the commands list their titles in the tables of contents, while others do not. Here are the details:

When a @setchapternewpage command says to do so, the @chapter, @unnumbered, and @appendix commands start new pages in the printed manual; the @heading commands do not. See section @setchapternewpage: Blank Pages Before Chapters.

Here is a summary:

No new page
NumberedUnnumberedLettered/numberedUnnumbered
In contentsIn contentsIn contentsNot in contents
@top@majorheading
@chapter@unnumbered@appendix@chapheading
@section@unnumberedsec@appendixsec@heading
@subsection@unnumberedsubsec@appendixsubsec@subheading
@subsubsection@unnumberedsubsubsec@appendixsubsubsec@subsubheading

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5.3 @chapter: Chapter Structuring

@chapter identifies a chapter in the document–the highest level of the normal document structuring hierarchy. Write the command at the beginning of a line and follow it on the same line by the title of the chapter. The chapter is numbered automatically, starting from 1.

For example, the present chapter in this manual is entitled “@chapter: Chapter Structuring”; the @chapter line looks like this:

@chapter @code{@@chapter}: Chapter Structuring

In TeX, the @chapter command produces a chapter heading in the document.

In Info and plain text output, the @chapter command causes the title to appear on a line by itself, with a line of asterisks inserted underneath. So, the above example produces the following output:

5 Chapter Structuring
*********************

In HTML, the @chapter command produces an <h2>-level header by default (controlled by the CHAPTER_HEADER_LEVEL customization variable, see section Other Customization Variables).

In the XML and Docbook output, a <chapter> element is produced that includes all the following sections, up to the next chapter.


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5.4 @unnumbered, @appendix: Chapters with Other Labeling

Use the @unnumbered command to start a chapter-level element that appears without chapter numbers of any kind. Use the @appendix command to start an appendix that is labeled by letter (‘A’, ‘B’, …) instead of by number; appendices are also at the chapter level of structuring.

Write an @appendix or @unnumbered command at the beginning of a line and follow it on the same line by the title, just as with @chapter.

Texinfo also provides a command @centerchap, which is analogous to @unnumbered, but centers its argument in the printed and HTML outputs. This kind of stylistic choice is not usually offered by Texinfo. It may be suitable for short documents.

With @unnumbered, if the name of the associated node is one of these English words (case-insensitive):

Acknowledgements  Colophon  Dedication  Preface

then the Docbook output uses corresponding special tags (<preface>, etc.) instead of the default <chapter>. The argument to @unnumbered itself can be anything, and is output as the following <title> text as usual.


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5.5 @majorheading, @chapheading: Chapter-level Headings

The @majorheading and @chapheading commands produce chapter-like headings in the body of a document.

However, neither command produces an entry in the table of contents, and neither command causes TeX to start a new page in a printed manual.

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

In Info and plain text, the @majorheading and @chapheading commands produce the same output as @chapter: the title is printed on a line by itself with a line of asterisks underneath. Similarly for HTML. The only difference is the lack of numbering and the lack of any association with nodes. See section @chapter: Chapter Structuring.


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5.6 @section: Sections Below Chapters

An @section command identifies a section within a chapter unit, whether created with @chapter, @unnumbered, or @appendix, following the numbering scheme of the chapter-level command. Thus, within a @chapter chapter numbered ‘1’, the sections are numbered ‘1.1’, ‘1.2’, etc.; within an @appendix “chapter” labeled ‘A’, the sections are numbered ‘A.1’, ‘A.2’, etc.; within an @unnumbered chapter, the section gets no number. The output is underlined with ‘=’ in Info and plain text.

To make a section, write the @section command at the beginning of a line and follow it on the same line by the section title. For example,

@section This is a section

might produce the following in Info:

5.7 This is a section
=====================

Section titles are listed in the table of contents.

The TeX, HTML, Docbook, and XML output is all analogous to the chapter-level output, just “one level down”; see section @chapter: Chapter Structuring.


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5.7 @unnumberedsec, @appendixsec, @heading

The @unnumberedsec, @appendixsec, and @heading commands are, respectively, the unnumbered, appendix-like, and heading-like equivalents of the @section command (see the previous section).

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

@unnumberedsec

The @unnumberedsec command may be used within an unnumbered chapter or within a regular chapter or appendix to produce an unnumbered section.

@appendixsec
@appendixsection

@appendixsection is a longer spelling of the @appendixsec command; the two are synonymous.

Conventionally, the @appendixsec or @appendixsection command is used only within appendices.

@heading

You may use the @heading command (almost) anywhere for a section-style heading that will not appear in the table of contents. The @heading-series commands can appear inside most environments, for example, though pathological and useless locations such as inside @titlepage, as an argument to another command, etc., are not allowed.


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5.8 @subsection: Subsections Below Sections

Subsections are to sections as sections are to chapters; see section @section: Sections Below Chapters. In Info and plain text, subsection titles are underlined with ‘-’. For example,

@subsection This is a subsection

might produce

1.2.3 This is a subsection
--------------------------

Subsection titles are listed in the table of contents.

The TeX, HTML, Docbook, and XML output is all analogous to the chapter-level output, just “two levels down”; see section @chapter: Chapter Structuring.


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5.9 The @subsection-like Commands

The @unnumberedsubsec, @appendixsubsec, and @subheading commands are, respectively, the unnumbered, appendix-like, and heading-like equivalents of the @subsection command. (See section @subsection: Subsections Below Sections.)

@unnumberedsubsec and @appendixsubsec do not need to be used in ordinary circumstances, because @subsection may also be used within sections of @unnumbered and @appendix chapters (see section @section: Sections Below Chapters).

An @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 @unnumberedsubsec command produces an unnumbered heading like that of a subsection and an @appendixsubsec command produces a subsection-like heading labeled with a letter and numbers; both of these commands produce headings that appear in the table of contents. In Info and plain text, the @subsection-like commands generate a title underlined with hyphens.


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5.10 @subsection and Other Subsub Commands

The fourth and lowest level sectioning commands in Texinfo are the ‘subsub’ commands. They are:

@subsubsection

Subsubsections are to subsections as subsections are to sections. (See section @subsection: Subsections Below Sections.) Subsubsection titles appear in the table of contents.

@unnumberedsubsubsec

Unnumbered subsubsection titles appear in the table of contents, but lack numbers. Otherwise, unnumbered subsubsections are the same as subsubsections.

@appendixsubsubsec

Conventionally, appendix commands are used only for appendices and are lettered and numbered appropriately. They also appear in the table of contents.

@subsubheading

The @subsubheading command may be used anywhere that you want a small heading that will not appear in the table of contents.

As with subsections, @unnumberedsubsubsec and @appendixsubsubsec do not need to be used in ordinary circumstances, because @subsubsection may also be used within subsections of @unnumbered and @appendix chapters (see section @section: Sections Below Chapters).

In Info, ‘subsub’ titles are underlined with periods. For example,

@subsubsection This is a subsubsection

might produce

1.2.3.4 This is a subsubsection
...............................

The TeX, HTML, Docbook, and XML output is all analogous to the chapter-level output, just “three levels down”; see section @chapter: Chapter Structuring.


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5.11 @part: Groups of Chapters

The final sectioning command is @part, to mark a part of a manual, that is, a group of chapters or (rarely) appendices. This behaves quite differently from the other sectioning commands, to fit with the way such “parts” are conventionally used in books.

No @node command is associated with @part. Just write the command on a line by itself, including the part title, at the place in the document you want to mark off as starting that part. For example:

@part Part I:@* The beginning

As can be inferred from this example, no automatic numbering or labeling of the @part text is done. The text is taken as-is.

Because parts are not associated with nodes, no general text can follow the @part line. To produce the intended output, it must be followed by a chapter-level command (including its node). Thus, to continue the example:

@part Part I:@* The beginning

@node Introduction
@chapter Introduction
...

In the TeX output, the @part text is included in both the normal and short tables of contents (see section Generating a Table of Contents), without a page number (since that is the normal convention). In addition, a “part page” is output in the body of the document, with just the @part text. In the example above, the @* causes a line break on the part page (but is replaced with a space in the tables of contents). This part page is always forced to be on an odd (right-hand) page, regardless of the chapter pagination (see section @setchapternewpage: Blank Pages Before Chapters).

In the HTML output, the @part text is similarly included in the tables of contents, and a heading is included in the main document text, as part of the following chapter or appendix node.

In the XML and Docbook output, the <part> element includes all the following chapters, up to the next <part>. A <part> containing chapters is also closed at an appendix.

In the Info and plain text output, @part has no effect.

@part is ignored when raising or lowering sections (see next section). That is, it is never lowered and nothing can be raised to it.


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5.12 Raise/lower Sections: @raisesections and @lowersections

The @raisesections and @lowersections commands implicitly raise and lower the hierarchical level of following chapters, sections and the other sectioning commands (excluding parts).

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

You can use @lowersections to include text written as an outer or standalone Texinfo file in another Texinfo file as an inner, included file (see section Include Files). Typical usage looks like this:

@lowersections
@include somefile.texi
@raisesections

(Without the @raisesections, all the subsequent sections in the main file would also be lowered.)

If the included file being lowered has a @top node, you’ll need to conditionalize its inclusion with a flag (see section @set and @value).

As a practical matter, you generally only want to raise or lower large chunks, usually in external files as shown above. The final result has to have menus that take the raising and lowering into account, so you cannot just arbitrarily sprinkle @raisesections and @lowersections commands throughout the document.

Repeated use of the commands continues 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 makeinfo’s feature of implicitly determining node pointers, since the menu structure cannot be represented correctly.

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


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6 Cross-references

Cross-references are used to refer the reader to other parts of the same or different Texinfo files.


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6.1 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.

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.

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. In Info, a cross-reference results in an entry that you can follow using the Info ‘f’ command. (See Following cross-references in Info.) In HTML, a cross-reference results in an hyperlink.

The various cross-reference commands use nodes (or anchors, see section @anchor: Defining Arbitrary Cross-reference Targets) to define cross-reference locations. TeX needs nodes to define cross-reference locations. When TeX generates a DVI file, it records each node’s page number and uses the page numbers in making references. Thus, even if you are writing a manual that will only be printed, and not used online, you must nonetheless write @node lines in order to name the places to which you make cross-references.


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6.2 Different Cross-reference Commands

There are three different cross-reference commands:

@xref

Used to start a sentence in the printed manual and in HTML with ‘See …’ or an Info cross-reference saying ‘*Note name: node.’.

@ref

Used within or, more often, at the end of a sentence; produces just the reference in the printed manual and in HTML without the preceding ‘See’ (same as @xref for Info).

@pxref

Used within parentheses, at the end of a sentence, or otherwise before punctuation, to make a reference. Its output starts with a lowercase ‘see’ in the printed manual and in HTML, and a lowercase ‘*note’ in Info. (‘p’ is for ‘parenthesis’.)

Additionally, there are commands to produce references to documents outside the Texinfo system. The @cite command is used to make references to books and manuals. @url produces a URL, for example a reference to a page on the World Wide Web. @inforef is used to make a reference to an Info file for which there is no printed manual.


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6.3 Parts of a Cross-reference

A cross-reference command requires only one argument, which is the name of the node to which it refers. Here is a simple example:

@xref{Node name}.

In Info output, this produces

*Note Node name::.

In a printed manual, the output is

See Section nnn [Node name], page ppp.

A cross-reference command may contain up to four additional arguments. By using these arguments, you can provide a cross-reference name, a topic description or section title for the printed output, the name of a different manual file, and the name of a different printed manual. To refer to another manual as a whole, the manual file and/or the name of the printed manual are the only required arguments (see section Referring to a Manual as a Whole).

Here is an example of a full five-part cross-reference:

@xref{Node name, Online Label, Printed Label,
info-file-name, A Printed Manual}, for details.

which produces

*Note Online Label: (info-file-name)Node name,
for details.

in Info and

See section “Printed Label” in A Printed Manual, for details.

in a printed book.

The five possible arguments for a cross-reference are:

  1. The node or anchor name (required, except for reference to whole manuals). 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. Use @node to define the node (see section Writing an @node Line), or @anchor (see section @anchor: Defining Arbitrary Cross-reference Targets).

    Write a node name in a cross-reference in exactly the same way as in the @node line, including the same capitalization; otherwise, the formatters may not find the reference.

  2. A label for online output. 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.
  3. A label for printed output. Often, this is the title or topic of the section. This is used as the name of the reference in the printed manual. If omitted, the node name is used.
  4. The name of the manual file in which the reference is located, if it is different from the current file. This name is used both for Info and HTML.
  5. The name of a printed manual from a different Texinfo file.

The template for a full five argument cross-reference looks like this:

@xref{node-name, online-label, printed-label,
info-file-name, printed-manual-title}

Whitespace before and after the commas separating these arguments is ignored. To include a comma in one of the arguments, use @comma{} (see section Inserting ‘,’ with @comma{}).

When processing with TeX, a comma is automatically inserted after the page number for cross-references to within the same manual, unless the closing brace of the argument is followed by non-whitespace (such as a comma or period). This gives you the choice of whether to have a comma there in Info or HTML output. For example,

@xref{Another Section} for more information

produces ‘See Another Section, page ppp, for more information’ in the printed output, and ‘*Note Another Section:: for more information’ in the Info output.

If an unwanted comma is added, follow the argument with a command such as ‘@:’. For example, ‘@xref{Hurricanes}@: --- for the details’ produces

See Hurricanes, page ppp — for the details

instead of ‘See Hurricanes, page ppp, — for the details’.

Cross-references with one, two, three, four, and five arguments are described separately following the description of @xref.

makeinfo warns when the text of a cross-reference (and node names and menu items) contains a problematic construct that will interfere with its parsing in Info. If you don’t want to see the warnings, you can set the customization variable INFO_SPECIAL_CHARS_WARNING to ‘0’ (see section Other Customization Variables).


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6.4 @xref

The @xref command generates a cross-reference for the beginning of a sentence.


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6.4.1 @xref with One Argument

The simplest form of @xref takes one argument, the name of another node in the same Texinfo file.

For example,

@xref{Tropical Storms}.

produces

*Note Tropical Storms::.

in Info and

See Section 3.1 [Tropical Storms], page 24.

in a printed manual.


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6.4.2 @xref with Two Arguments

With two arguments, the second is used as a label for the online output.

The template is like this:

@xref{node-name, online-label}.

For example,

@xref{Electrical Effects, Lightning}.

produces:

*Note Lightning: Electrical Effects.

in Info and

See Section 5.2 [Electrical Effects], page 57.

in a printed manual, where the node name is printed.

The second argument to cross-references must observe some of the restrictions for node names (see section @node Line Requirements). The most common issue is that colons cannot be used, since that interferes with the parsing of the Info file.


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6.4.3 @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.

The template is like this:

@xref{node-name, online-label, printed-label}.

For example,

@xref{Electrical Effects, Lightning, Thunder and Lightning},
for details.

produces

*Note Lightning: Electrical Effects, for details.

in Info and

See Section 5.2 [Thunder and Lightning], page 57, for details.

in a printed manual.

If a third argument is given and the second one is empty, then the third argument serves for both. (Note how two commas, side by side, mark the empty second argument.)

@xref{Electrical Effects, , Thunder and Lightning},
for details.

produces

*Note Thunder and Lightning: Electrical Effects, for details.

in Info and

See Section 5.2 [Thunder and Lightning], page 57, for details.

in a printed manual.

The third argument to cross-references must observe some of the restrictions for node names (see section @node Line Requirements). The most common issue is that colons cannot be used, since that interferes with the parsing of the Info file.

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 (or nearly so), and with the first and third arguments only if the node name and title are different.

Texinfo offers a setting to use the section title instead of node names by default in cross-references (an explicitly specified third argument still takes precedence):

@xrefautomaticsectiontitle on

Typically this line would be given near the beginning of the document and used for the whole manual. But you can turn it off if you want (@xrefautomaticsectiontitle off), for example, if you’re including some other sub-document that doesn’t have suitable section names.


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6.4.4 @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.

The full template is:

@xref{node-name, online-label, printed-label,
info-file-name, printed-manual-title}.

For example,

@xref{Electrical Effects, Lightning, Thunder and Lightning,
weather, An Introduction to Meteorology}.

produces this output in Info:

*Note Lightning: (weather)Electrical Effects.

As you can see, the name of the Info file is enclosed in parentheses and precedes the name of the node.

In a printed manual, the reference looks like this:

See section “Thunder and Lightning” in An Introduction to Meteorology.

The title of the printed manual is typeset like @cite; and the reference lacks a page number since TeX cannot know to which page a reference refers when that reference is to another manual.

Next case: often, you will leave out the second argument when you use the long version of @xref. In this case, the third argument, the topic description, will be used as the cross-reference name in Info. For example,

@xref{Electrical Effects, , Thunder and Lightning,
weather, An Introduction to Meteorology}.

produces

*Note Thunder and Lightning: (weather)Electrical Effects.

in Info and

See section “Thunder and Lightning” in An Introduction to Meteorology.

in a printed manual.

Next case: If the node name and the section title are the same in the other manual, you may also leave out the section title. In this case, the node name is used in both instances. For example,

@xref{Electrical Effects,,,
weather, An Introduction to Meteorology}.

produces

*Note (weather)Electrical Effects::.

in Info and

See section “Electrical Effects” in An Introduction to Meteorology.

in a printed manual.

A very unusual case: you may want to refer to another manual file that is within a single printed manual—when multiple Texinfo files are incorporated into the same TeX run but can create separate Info or HTML output files. In this case, you need to specify only the fourth argument, and not the fifth.

Finally, it’s also allowed to leave out all the arguments except the fourth and fifth, to refer to another manual as a whole. See the next section.


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6.5 Referring to a Manual as a Whole

Ordinarily, you must always name a node in a cross-reference. However, it’s not unusual to want to refer to another manual as a whole, rather than a particular section within it. In this case, giving any section name is an unnecessary distraction.

So, with cross-references to other manuals (see section @xref with Four and Five Arguments), if the first argument is either ‘Top’ (capitalized just that way) or omitted entirely, and the third argument is omitted, the printed output includes no node or section name. (The Info output includes ‘Top’ if it was given.) For example,

@xref{Top,,, make, The GNU Make Manual}.

produces

*Note (make)Top::.

and

See The GNU Make Manual.

Info readers will go to the Top node of the manual whether or not the ‘Top’ node is explicitly specified.

It’s also possible (and is historical practice) to refer to a whole manual by specifying the ‘Top’ node and an appropriate entry for the third argument to the @xref command. Using this idiom, to make a cross-reference to The GNU Make Manual, you would write:

@xref{Top,, Overview, make, The GNU Make Manual}.

which produces

*Note Overview: (make)Top.

in Info and

See section “Overview” in The GNU Make Manual.

in a printed manual.

In this example, ‘Top’ is the name of the first node, and ‘Overview’ is the name of the first section of the manual. There is no widely-used convention for naming the first section in a printed manual, this is just what the Make manual happens to use. This arbitrariness of the first name is a principal reason why omitting the third argument in whole-manual cross-references is preferable.


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6.6 @ref

@ref is nearly the same as @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.

For example,

For more information, @pxref{This}, and @ref{That}.

produces in Info:

For more information, *note This::, and *note That::.

and in printed output:

For more information, see Section 1.1 [This], page 1, and Section 1.2 [That], page 2.

The @ref command can tempt 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 could be using both the printed and the Info format. For example:

Sea surges are described in @ref{Hurricanes}.

looks ok in the printed output:

Sea surges are described in Section 6.7 [Hurricanes], page 72.

but is awkward to read in Info, “note” being a verb:

Sea surges are described in *note Hurricanes::.

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6.7 @pxref

The parenthetical reference command, @pxref, is nearly the same as @xref, but it is best used at the end of a sentence or before a closing parenthesis. The command differs from @xref in that TeX typesets the reference for the printed manual with a lowercase ‘see’ rather than an uppercase ‘See’.

With one argument, a parenthetical cross-reference looks like this:

… storms cause flooding (@pxref{Hurricanes}) …

which produces

… storms cause flooding (*note Hurricanes::) …

in Info and

… storms cause flooding (see Section 6.7 [Hurricanes], page 72) …

in a printed manual.

With two arguments, a parenthetical cross-reference has this template:

… (@pxref{node-name, cross-reference-name}) …

which produces

… (*note cross-reference-name: node-name.) …

in Info and

… (see Section nnn [node-name], page ppp) …

in a printed manual.

@pxref can be used with up to five arguments, just like @xref (see section @xref).

In past versions of Texinfo, it was not allowed to write punctuation after a @pxref, so it could be used 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:

… For more information, @pxref{More}.

which outputs (in Info):

… For more information, *note More::.

As a matter of style, @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.


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6.8 @anchor: Defining Arbitrary Cross-reference Targets

An anchor is a position in your document, labelled so that cross-references can refer to it, just as they can to nodes. You create an anchor with the @anchor command, and give the label as a normal brace-delimited argument. For example:

This marks the @anchor{x-spot}spot.
…
@xref{x-spot,,the spot}.

produces:

This marks the spot.
…
See [the spot], page 1.

As you can see, the @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 @xref or other cross reference command, as shown (see section Cross-references).

It is best to put @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 @anchor command on a line by itself if that helps readability of the source. Whitespace (including newlines) is ignored after @anchor.

Anchor names and node names may not conflict. Anchors and nodes are given similar treatment in some ways; for example, the goto-node command takes either an anchor name or a node name as an argument. (See Go to node in Info.)

Also like node names, anchor names cannot include some characters (see section @node Line Requirements).

Because of this duality, when you delete or rename a node, it is usually a good idea to define an @anchor with the old name. That way, any links to the old node, whether from other Texinfo manuals or general web pages, keep working. You can also do this with the ‘RENAMED_NODES_FILE’ feature of makeinfo (see section HTML Cross-reference Link Preservation: manual-noderename.cnf). Both methods keep links on the web working; the only substantive difference is that defining anchors also makes the old node names available when reading the document in Info.


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6.9 @inforef: Cross-references to Info-only Material

@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 @ifinfo text (see section Conditionally Visible Text), 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:

  1. The node name.
  2. The cross-reference name (optional).
  3. The Info file name.

The template is:

@inforef{node-name, cross-reference-name, info-file-name}

For example,

@inforef{Advanced, Advanced Info commands, info},
for more information.

produces (in Info):

*Note Advanced Info commands: (info)Advanced,
for more information.

and (in the printed output):

See Info file ‘info’, node ‘Advanced’, for more information.

(This particular example is not realistic, since the Info manual is written in Texinfo, so all formats are available. In fact, we don’t know of any extant Info-only manuals.)

The converse of @inforef is @cite, which is used to refer to printed works for which no Info form exists. See section @cite{reference}.


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6.10 @url, @uref{url[, text][, replacement]}

@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 and PDF output, @uref produces a link you can follow. (To merely indicate a url without creating a link people can follow, use @indicateurl, see section @indicateurl{uniform-resource-locator}.)

@url is a synonym for @uref. (Originally, @url had the meaning of @indicateurl, but in practice it was almost always misused. So we’ve changed the meaning.)

The second argument, if specified, is the text to display (the default is the url itself); in Info, DVI, and PDF output, but not in HTML output, the url is output in addition to this text.

The third argument, if specified, is the text to display, but in this case the url is not output in any format. This is useful when the text is already sufficiently referential, as in a man page. Also, if the third argument is given, the second argument is ignored.


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6.10.1 @url Examples

First, here is an example of the simplest form of @url, with just one argument. The given url is both the target and the visible text of the link:

The official GNU ftp site is @uref{http://ftp.gnu.org/gnu}.

produces:

The official GNU ftp site is http://ftp.gnu.org/gnu.

Two-argument form of @url

Here is an example of the two-argument form:

The official @uref{http://ftp.gnu.org/gnu, GNU ftp site}
holds programs and texts.

which produces:

The official GNU ftp site
holds programs and texts.

that is, the Info (and TeX, etc.) output is this:

The official GNU ftp site (http://ftp.gnu.org/gnu)
holds programs and texts.

while the HTML output is this:

The official <a href="http://ftp.gnu.org/gnu">GNU ftp site</a>
holds programs and texts.

Three-argument form of @url

Finally, an example of the three-argument form:

The @uref{/man.cgi/1/ls,,ls} program …

which, except for HTML, produces:

The ls program …

but with HTML:

The <a href="/man.cgi/1/ls">ls</a> program …

By the way, some people prefer to display urls in the unambiguous format:

<URL:http://host/path>

You can use this form in the input file if you wish. We feel it’s not necessary to include the ‘<URL:’ and ‘>’ in the output, since to be useful any software that tries to detect urls in text already has to detect them without the ‘<URL:’.


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6.10.2 URL Line Breaking

TeX allows line breaking within urls at only a few characters (which are special in urls): ‘&’, ‘.’, ‘#’, ‘?’, and ‘/’ (but not between two ‘/’ characters). A tiny amount of stretchable space is also inserted around these characters to help with line breaking.

For HTML output, modern browsers will also do line breaking within displayed urls. If you need to allow breaks at other characters you can insert @/ as needed (see section @* and @/: Generate and Allow Line Breaks).

By default, in TeX any such breaks at special characters will occur after the character. Some people prefer such breaks to happen before the special character. This can be controlled with the @urefbreakstyle command (this command has effect only in TeX):

@urefbreakstyle how

where the argument how is one of these words:

after

(the default) Potentially break after the special characters.

before

Potentially break before the special characters.

none

Do not consider breaking at the special characters at all; any potential breaks must be manually inserted.


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6.10.3 @url PDF Output Format

If the ultimate purpose of a PDF is only to be viewed online, perhaps similar to HTML in some inchoate way, you may not want the urls to be included in the visible text (just as urls are not visible to readers of web pages). Texinfo provides a PDF-specific option for this, which must be used inside @tex:

@tex
\global\urefurlonlylinktrue
@end tex

The result is that @url{http://www.gnu.org, GNU} has the visible output of just ‘GNU’, with a link target of http://www.gnu.org. Ordinarily, the visible output would include both the label and the url: ‘GNU (http://www.gnu.org)’.

This option only has effect when the PDF output is produced with the pdfTeX program, not with other ways of getting from Texinfo to PDF (e.g., TeX to DVI to PDF). Consequently, it is ok to specify this option unconditionally within @tex, as shown above. It is ignored when DVI is being produced.


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6.10.4 PDF Colors

By default, urls and cross-reference links are printed in black in PDF output. Very occasionally, however, you may want to highlight such “live” links with a different color, as is commonly done on web pages. Texinfo provides a PDF-specific option for specifying these colors, which must be used inside @tex:

@tex
\global\def\linkcolor{1 0 0}  % red
\global\def\urlcolor{0 1 0}   % green
@end tex

\urlcolor changes the color of @url output (both the actual url and any textual label), while \linkcolor changes the color for cross-references to nodes, etc. They are independent.

The three given values must be numbers between 0 and 1, specifying the amount of red, green, and blue respectively.

These definitions only have an effect when the PDF output is produced with the pdfTeX program, not with other ways of getting from Texinfo to PDF (e.g., TeX to DVI to PDF). Consequently, it is ok to specify this option unconditionally within @tex, as shown above. It is ignored when DVI is being produced.

We do not recommend colorizing just for fun; unless you have a specific reason to use colors, best to skip it.


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6.11 @cite{reference}

Use the @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. See section @xref.


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7 Marking Text, Words and Phrases

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.


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7.1 Indicating Definitions, Commands, etc.

Texinfo has commands for indicating just what kind of object a piece of text refers to. For example, email addresses are marked by @email; that way, the result can be a live link to send email when the output format supports it. If the email address was simply marked as “print in a typewriter font”, that would not be possible.


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7.1.1 Highlighting Commands are Useful

The commands serve a variety of purposes:

@code{sample-code}

Indicate text that is a literal example of a piece of a program. See section @code{sample-code}.

@kbd{keyboard-characters}

Indicate keyboard input. See section @kbd{keyboard-characters}.

@key{key-name}

Indicate the conventional name for a key on a keyboard. See section @key{key-name}.

@samp{text}

Indicate text that is a literal example of a sequence of characters. See section @samp{text}.

@verb{text}

Write a verbatim sequence of characters. See section @verb{chartextchar}.

@var{metasyntactic-variable}

Indicate a metasyntactic variable. See section @var{metasyntactic-variable}.

@env{environment-variable}

Indicate an environment variable. See section @env{environment-variable}.

@file{file-name}

Indicate the name of a file. See section @file{file-name}.

@command{command-name}

Indicate the name of a command. See section @command{command-name}.

@option{option}

Indicate a command-line option. See section @option{option-name}.

@dfn{term}

Indicate the introductory or defining use of a term. See section @dfn{term}.

@cite{reference}

Indicate the name of a book. See section @cite{reference}.

@abbr{abbreviation}

Indicate an abbreviation, such as ‘Comput.’.

@acronym{acronym}

Indicate an acronym. See section @acronym{acronym[, meaning]}.

@indicateurl{uniform-resource-locator}

Indicate an example (that is, nonfunctional) uniform resource locator. See section @indicateurl{uniform-resource-locator}. (Use @url (see section @url, @uref{url[, text][, replacement]}) for live urls.)

@email{email-address[, displayed-text]}

Indicate an electronic mail address. See section @email{email-address[, displayed-text]}.


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7.1.2 @code{sample-code}

Use the @code command to indicate text that is a piece of a program and which consists of entire syntactic tokens. Enclose the text in braces.

Thus, you should use @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 for command names in languages that resemble programming languages, such as Texinfo. For example, @code and @samp are produced by writing ‘@code{@@code}’ and ‘@code{@@samp}’ in the Texinfo source, respectively.

It is incorrect to alter the case of a word inside a @code command when it appears at the beginning of a sentence. Most computer languages are case sensitive. In C, for example, Printf is different from the identifier 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 lowercase, you should rearrange the sentence.

In the Info output, @code results in single quotation marks around the text. In other formats, @code argument is typeset in a typewriter (monospace) font. For example,

The function returns @code{nil}.

produces this:

The function returns nil.

Here are some cases for which it is preferable not to use @code:

By default, TeX will consider breaking lines at ‘-’ and ‘_’ characters within @code and related commands. This can be controlled with @allowcodebreaks (see section @allowcodebreaks: Control Line Breaks in @code). The HTML output attempts to respect this for ‘-’, but ultimately it is up to the browser’s behavior. For Info, it seems better never to make such breaks.

For Info, the quotes are omitted in the output of the @code command and related commands (e.g., @kbd, @command), in typewriter-like contexts such as the @example environment (see section @example: Example Text) and @code itself, etc.

To control which quoting characters are implicitly inserted by Texinfo processors in the output of ‘@code’, etc., see the OPEN_QUOTE_SYMBOL and CLOSE_QUOTE_SYMBOL customization variables (see section Other Customization Variables). This is separate from how actual quotation characters in the input document are handled (see section Inserting Quote Characters).


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7.1.3 @kbd{keyboard-characters}

Use the @kbd command for characters of input to be typed by users. For example, to refer to the characters M-a, write:

@kbd{M-a}

and to refer to the characters M-x shell, write:

@kbd{M-x shell}

By default, the @kbd command produces a different font (slanted typewriter instead of normal typewriter), so users can distinguish the characters that they are supposed to type from those that the computer outputs.

Since the usage of @kbd varies from manual to manual, you can control the font switching with the @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:

code

Always use the same font for @kbd as @code.

example

Use the distinguishing font for @kbd only in @example and similar environments.

distinct

(the default) Always use the distinguishing font for @kbd.

You can embed another @-command inside the braces of a @kbd command. Here, for example, is the way to describe a command that would be described more verbosely as “press the ‘r’ key and then press the <RETURN> key”:

@kbd{r @key{RET}}

This produces: r <RET>. (The present manual uses the default for @kbdinputstyle.)

You also use the @kbd command if you are spelling out the letters you type; for example:

To give the @code{logout} command,
type the characters @kbd{l o g o u t @key{RET}}.

This produces:

To give the logout command, type the characters l o g o u t <RET>.

(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 @key{SPC} for it.)


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7.1.4 @key{key-name}

Use the @key command for the conventional name for a key on a keyboard, as in:

@key{RET}

You can use the @key command within the argument of an @kbd command when the sequence of characters to be typed includes one or more keys that are described by name.

For example, to produce C-x <ESC> and M-<TAB> you would type:

@kbd{C-x @key{ESC}}
@kbd{M-@key{TAB}}

Here is a list of the recommended names for keys:

SPC

Space

RET

Return

LFD

Linefeed (however, since most keyboards nowadays do not have a Linefeed key, it might be better to call this character C-j)

TAB

Tab

BS

Backspace

ESC

Escape

DELETE

Delete

SHIFT

Shift

CTRL

Control

META

Meta

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 Meta-a, use the @kbd command alone; do not use the @key command; but when you are referring to the modifier key in isolation, use the @key command. For example, write ‘@kbd{Meta-a}’ to produce Meta-a and ‘@key{META}’ to produce <META>.

As a convention in GNU manuals, @key should not be used in index entries.


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7.1.5 @samp{text}

Use the @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.

To match @samp{foo} at the end of the line,
use the regexp @samp{foo$}.

produces

To match ‘foo’ at the end of the line, use the regexp ‘foo$’.

Any time you are referring to single characters, you should use @samp unless @kbd or @key is more appropriate. Also, you may use @samp for entire statements in C and for entire shell commands—in this case, @samp often looks better than @code. Basically, @samp is a catchall for whatever is not covered by @code, @kbd, @key, @command, etc.

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:

In English, the vowels are @samp{a}, @samp{e},
@samp{i}, @samp{o}, @samp{u}, and sometimes
@samp{y}.

This produces:

In English, the vowels are ‘a’, ‘e’, ‘i’, ‘o’, ‘u’, and sometimes ‘y’.


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7.1.6 @verb{chartextchar}

Use the @verb command to print a verbatim sequence of characters.

Like LaTeX’s \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:

How many @verb{|@|}-escapes does one need to print this
@verb{.@a @b.@c.} string or @verb{+@'e?`{}!`\+} this?

produces

How many @-escapes does one need to print this
@a @b.@c string or @'e?`{}!`\ this?

This is in contrast to @samp (see the previous section), @code, and similar commands; in those cases, the argument is normal Texinfo text, where the three characters @{} are special, as usual. With @verb, nothing is special except the delimiter character you choose.

The delimiter character itself may appear inside the verbatim text, as shown above. As another example, ‘@verb{...}’ prints a single (fixed-width) period.

It is not reliable to use @verb inside other Texinfo constructs. In particular, it does not work to use @verb in anything related to cross-referencing, such as section titles or figure captions.


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7.1.7 @var{metasyntactic-variable}

Use the @var command to indicate metasyntactic variables. A 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.

Do not use @var for the names of normal variables in computer programs. These are specific names, so @code is correct for them (@code). For example, the Emacs Lisp variable texinfo-tex-command is not a metasyntactic variable; it is properly formatted using @code.

Do not use @var for environment variables either; @env is correct for them (see the next section).

The effect of @var in the Info file is to change the case of the argument to all uppercase. In the printed manual and HTML output, the argument is output in slanted type.

For example,

To delete file @var{filename},
type @samp{rm @var{filename}}.

produces

To delete file filename, type ‘rm filename’.

(Note that @var may appear inside @code, @samp, @file, etc.)

Write a metasyntactic variable all in lowercase 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:

\input texinfo
@@settitle @var{name-of-manual}

This produces:

\input texinfo
@settitle name-of-manual

In some documentation styles, metasyntactic variables are shown with angle brackets, for example:

…, type rm <filename>

However, that is not the style that Texinfo uses.


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7.1.8 @env{environment-variable}

Use the @env command to indicate environment variables, as used by many operating systems, including GNU. Do not use it for metasyntactic variables; use @var for those (see the previous section).

@env is equivalent to @code in its effects. For example:

The @env{PATH} environment variable …

produces

The PATH environment variable …


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7.1.9 @file{file-name}

Use the @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 @file for symbols in a programming language; use @code.

@file is equivalent to code in its effects. For example,

The @file{.el} files are in
the @file{/usr/local/emacs/lisp} directory.

produces

The ‘.el’ files are in the ‘/usr/local/emacs/lisp’ directory.


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7.1.10 @command{command-name}

Use the @command command to indicate command names, such as ls or cc.

@command is equivalent to @code in its effects. For example:

The command @command{ls} lists directory contents.

produces

The command ls lists directory contents.

You should write the name of a program in the ordinary text font, rather than using @command, if you regard it as a new English word, such as ‘Emacs’ or ‘Bison’.

When writing an entire shell command invocation, as in ‘ls -l’, you should use either @samp or @code at your discretion.


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7.1.11 @option{option-name}

Use the @option command to indicate a command-line option; for example, ‘-l’ or ‘--version’ or ‘--output=filename’.

@option is equivalent to @code in its effects. For example:

The option @option{-l} produces a long listing.

produces

The option ‘-l’ produces a long listing.


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7.1.12 @dfn{term}

Use the @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 @dfn. The command generates italics in the printed manual, and double quotation marks in the Info file. For example:

Getting rid of a file is called @dfn{deleting} it.

produces

Getting rid of a file is called deleting it.

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.


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7.1.13 @abbr{abbreviation[, meaning]}

You can use the @abbr command for general abbreviations. The abbreviation is given as the single argument in braces, as in ‘@abbr{Comput.}’. As a matter of style, or for particular abbreviations, you may prefer to omit periods, as in ‘@abbr{Mr} Stallman’.

@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 @. command (see section Ending a Sentence) to get the correct spacing. However, you do not have to use @. within the abbreviation itself; Texinfo automatically assumes periods within the abbreviation do not end a sentence.

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 the <abbr> tag is used; in Docbook, the <abbrev> tag is used. For instance:

@abbr{Comput. J., Computer Journal}

produces:

Comput. J. (Computer Journal)

For abbreviations consisting of all capital letters, you may prefer to use the @acronym command instead. See the next section for more on the usage of these two commands.


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7.1.14 @acronym{acronym[, meaning]}

You can use the @acronym command for abbreviations written in all capital letters, such as ‘NASA’. The abbreviation is given as the single argument in braces, as in ‘@acronym{NASA}’. As a matter of style, or for particular acronyms, you may prefer to use periods, as in ‘@acronym{N.A.S.A.}’.

@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 @. or similar command (see section Ending a Sentence) to get the correct spacing.

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 and Docbook the <acronym> tag is used.

For instance (since GNU is a recursive acronym, we use @acronym recursively):

@acronym{GNU, @acronym{GNU}'s Not Unix}

produces:

GNU (@acronym{GNU}'s Not Unix)

In some circumstances, it is conventional to print family names in all capitals. Don’t use @acronym for this, since a name is not an acronym. Use @sc instead (see section @sc{text}: The Small Caps Font).

@abbr and @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.


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7.1.15 @indicateurl{uniform-resource-locator}

Use the @indicateurl command to indicate a uniform resource locator on the World Wide Web. This is purely for markup purposes and does not produce a link you can follow (use the @url or @uref command for that, see section @url, @uref{url[, text][, replacement]}). @indicateurl is useful for urls which do not actually exist. For example:

For example, the url might be @indicateurl{http://example.org/path}.

which produces:

For example, the url might be <http://example.org/path>.

The output from @indicateurl is more or less like that of @samp (see section @samp{text}).


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7.1.16 @email{email-address[, displayed-text]}

Use the @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).

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, @email produces a ‘mailto’ link that usually brings up a mail composition window. For example:

Send bug reports to @email{bug-texinfo@@gnu.org},
suggestions to the @email{bug-texinfo@@gnu.org, same place}.

produces

Send bug reports to bug-texinfo@gnu.org,
suggestions to the same place.

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7.2 Emphasizing Text

Usually, Texinfo changes the font to mark words in the text according to the category the words belong to; an example is the @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 text will be output. These commands have no effect in Info and only one of them, the @r command, has any regular use.


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7.2.1 @emph{text} and @strong{text}

The @emph and @strong commands are for emphasis; @strong is stronger. In printed output, @emph produces italics and @strong produces bold. In the Info output, @emph surrounds the text with underscores (‘_’), and @strong puts asterisks around the text.

For example,

@strong{Caution:} @samp{rm * .[^.]*}
removes @emph{all} files in the directory.

produces the following:

Caution: ‘rm * .[^.]*’ removes all files in the directory.

The @strong command is seldom used except to mark what is, in effect, a typographical element, such as the word ‘Caution’ in the preceding example.

Caution: Do not use @strong with the word ‘Note’ followed by a space; Info will mistake the combination for a cross-reference. Use a phrase such as Please notice or Caution instead, or the optional argument to @quotation—‘Note’ is allowable there.


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7.2.2 @sc{text}: The Small Caps Font

Use the ‘@sc’ command to set text in A SMALL CAPS FONT (where possible). Write the text you want to be in small caps between braces in lowercase, like this:

Richard @sc{Stallman} commencé GNU.

This produces:

Richard STALLMAN commencé GNU.

As shown here, we recommend reserving @sc for special cases where you want typographic small caps; family names are one such, especially in languages other than English, though there are no hard-and-fast rules about such things.

TeX typesets any uppercase letters between the braces of an @sc command in full-size capitals; only lowercase letters are printed in the small caps font. In the Info output, the argument to @sc is printed in all uppercase. In HTML, the argument is uppercased and the output marked with the <small> tag to reduce the font size, since HTML cannot easily represent true small caps.

Overall, we recommend using standard upper- and lowercase letters wherever possible.


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7.2.3 Fonts for Printing

Texinfo provides one command to change the size of the main body font in the TeX output for a document: @fonttextsize. It has no effect in other output. It takes a single argument on the remainder of the line, which must be either ‘10’ or ‘11’. For example:

@fonttextsize 10

The effect is to reduce the body font to a 10pt size (the default is 11pt). Fonts for other elements, such as sections and chapters, are reduced accordingly. This should only be used in conjunction with @smallbook (see section @smallbook: Printing “Small” Books) or similar, since 10pt 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.

Texinfo also provides a number of font commands that specify font changes in the printed manual and (where possible) in the HTML output. They have no effect in Info. All the commands apply to a following argument surrounded by braces.

@b

selects bold face;

@i

selects an italic font;

@r

selects a roman font, which is the usual font in which text is printed. It may or may not be seriffed.

@sansserif

selects a sans serif font;

@slanted

selects a slanted font;

@t

selects the fixed-width, typewriter-style font used by @code;

(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 infrequently needed features.)

The @r command can be useful in example-like environments, to write comments in the standard roman font instead of the fixed-width font. This looks better in printed output, and produces a <lineannotation> tag in Docbook output.

For example,

@lisp
(+ 2 2)    ; @r{Add two plus two.}
@end lisp

produces

(+ 2 2)    ; Add two plus two.

The @t command can occasionally be useful to produce output in a typewriter font where that is supported (e.g., HTML and PDF), but no distinction is needed in Info or plain text: @t{foo} produces foo, cf. @code{foo} producing foo.

In general, the other font commands are unlikely to be useful; they exist primarily to make it possible to document the functionality of specific font effects, such as in TeX and related packages.


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8 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.

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 @end command that is also at the beginning of a line by itself. For instance, you begin an example by writing @example by itself at the beginning of a line and end the example by writing @end example on a line by itself, at the beginning of that line, and with only one space between the @end and the example.


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8.1 Block Enclosing Commands

Here is a summary of commands that enclose blocks of text, also known as environments. They’re explained further in the following sections.

@quotation

Indicate text that is quoted. The text is filled, indented (from both margins), and printed in a roman font by default.

@indentedblock

Like @quotation, but the text is indented only on the left.

@example

Illustrate code, commands, and the like. The text is printed in a fixed-width font, and indented but not filled.

@lisp

Like @example, but specifically for illustrating Lisp code. The text is printed in a fixed-width font, and indented but not filled.

@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 @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.

@display

Display illustrative text. The text is indented but not filled, and no font is selected (so, by default, the font is roman).

@format

Like @display (the text is not filled and no font is selected), but the text is not indented.

@smallquotation
@smallindentedblock
@smallexample
@smalllisp
@smalldisplay
@smallformat

These @small... commands are just like their non-small counterparts, except that they output text in a smaller font size, where possible.

@flushleft
@flushright

Text is not filled, but is set flush with the left or right margin, respectively.

@raggedright

Text is filled, but only justified on the left, leaving the right margin ragged.

@cartouche

Highlight text, often an example or quotation, by drawing a box with rounded corners around it.

The @exdent command is used within the above constructs to undo the indentation of a line.

The @noindent command may be used after one of the above constructs (or at the beginning of any paragraph) to prevent the following text from being indented as a new paragraph.


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8.2 @quotation: Block Quotations

The text of a quotation is processed like normal text (regular font, text is filled) except that:

This is an example of text written between a @quotation command and an @end quotation command. A @quotation command is most often used to indicate text that is excerpted from another (real or hypothetical) printed work.

Write a @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 @end quotation. The @end quotation line will likewise disappear from the output.

@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 ‘:’. For example:

@quotation Note
This is
a foo.
@end quotation

produces

Note: This is a foo.

If the @quotation argument is one of these English words (case-insensitive):

Caution  Important  Note  Tip  Warning

then the Docbook output uses corresponding special tags (<note>, etc.) instead of the default <blockquote>. HTML output always uses <blockquote>.

If the author of the quotation is specified in the @quotation block with the @author command, a line with the author name is displayed after the quotation:

@quotation
People sometimes ask me if it is a sin in the Church of Emacs to use
vi.  Using a free version of vi is not a sin; it is a penance.  So happy
hacking.

@author Richard Stallman
@end quotation

produces

People sometimes ask me if it is a sin in the Church of Emacs to use vi. Using a free version of vi is not a sin; it is a penance. So happy hacking.

Richard Stallman

Texinfo also provides a command @smallquotation, which is just like @quotation but uses a smaller font size where possible. See section @small… Block Commands.


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8.3 @indentedblock: Indented text blocks

The @indentedblock environment is similar to @quotation, except that text is only indented on the left (and there is no optional argument for an author). Thus, the text font remains unchanged, and text is gathered and filled as usual, but the left margin is increased. For example:

@indentedblock This is an example of text written between an @indentedblock command and an @end indentedblock command. The @indentedblock environment can contain any text or other commands desired. @end indentedblock

This is written in the Texinfo source as:

@indentedblock
This is an example ...
@end indentedblock

Texinfo also provides a command @smallindentedblock, which is just like @indentedblock but uses a smaller font size where possible. See section @small… Block Commands.


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8.4 @example: Example Text

The @example environment is used to indicate an example that is not part of the running text, such as computer input or output. Write an @example command at the beginning of a line by itself. Mark the end of the example with an @end example command, also written at the beginning of a line by itself.

An @example environment has the following characteristics:

For example,

@example
cp foo @var{dest1}; \
 cp foo @var{dest2}
@end example

produces

cp foo dest1; \
 cp foo dest2

The lines containing @example and @end example will disappear from the output. To make the output look good, you should put a blank line before the @example and another blank line after the @end example. Blank lines inside the beginning @example and the ending @end example, on the other hand, do appear in the output.

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 M-x untabify to convert tabs in a region to multiple spaces.

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 @noindent command prevents a piece of text from being indented as if it were a new paragraph (see section @noindent: Omitting Indentation).

If you want to embed code fragments within sentences, instead of displaying them, use the @code command or its relatives (see section @code{sample-code}).

If you wish to write a “comment” on a line of an example in the normal roman font, you can use the @r command (see section Fonts for Printing).


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8.5 @verbatim: Literal Text

Use the @verbatim environment for printing of text that may contain special characters or commands that should not be interpreted, such as computer input or output (@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 @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 an @end verbatim command, also written at the beginning of a line by itself. The @end verbatim will also disappear from the output.

For example:

@verbatim
{
<TAB>@command with strange characters: @'e
expand<TAB>me
}
@end verbatim

This produces:

{
        @command with strange characters: @'e
expand	me
}

Since the lines containing @verbatim and @end verbatim produce no output, typically you should put a blank line before the @verbatim and another blank line after the @end verbatim. Blank lines between the beginning @verbatim and the ending @end verbatim will appear in the output.

You can get a “small” verbatim by enclosing the @verbatim in an @smallformat environment, as shown here:

@smallformat
@verbatim
... still verbatim, but in a smaller font ...
@end verbatim
@end smallformat

Finally, a word of warning: it is not reliable to use @verbatim inside other Texinfo constructs.

See also @verbatiminclude file: Include a File Verbatim.


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8.6 @lisp: Marking a Lisp Example

The @lisp command is used for Lisp code. It is synonymous with the @example command.

This is an example of text written between an
@lisp command and an @end lisp command.

Use @lisp instead of @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. Mark the end of @lisp with @end lisp on a line by itself.


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8.7 @display: Examples Using the Text Font

The @display command begins another kind of environment, where the font is left unchanged, not switched to typewriter as with @example. Each line of input still produces a line of output, and the output is still indented.

This is an example of text written between a @display command
and an @end display command.  The @display command
indents the text, but does not fill it.

Texinfo also provides the environment @smalldisplay, which is like @display but uses a smaller font size. See section @small… Block Commands.


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8.8 @format: Examples Using the Full Line Width

The @format command is similar to @display, except it leaves the text unindented. Like @display, it does not select the fixed-width font.

This is an example of text written between a @format command
and an @end format command.  As you can see
from this example,
the @format command does not fill the text.

Texinfo also provides the environment @smallformat, which is like @format but uses a smaller font size. See section @small… Block Commands.


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8.9 @exdent: Undoing a Line’s Indentation

The @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 @exdent line is printed in the roman font.

@exdent is usually used within examples. Thus,

@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

produces

This line follows an @example command.
This line is exdented.
This line follows the exdented line.
The @end example comes on the next line.

In practice, the @exdent command is rarely used. Usually, you un-indent text by ending the example and returning the page to its normal width.

@exdent has no effect in HTML output.


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8.10 @flushleft and @flushright

The @flushleft and @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 @flushleft and @flushright commands are ended by @end flushleft and @end flushright commands on lines of their own.

For example,

@flushleft
This text is
written flushleft.
@end flushleft

produces

This text is written flushleft.

@flushright produces the type of indentation often used in the return address of letters. For example,

@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

produces

Here is an example of text written flushright. The @flushright command right justifies every line but leaves the left end ragged.


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8.11 @raggedright: Ragged Right Text

The @raggedright fills text as usual, but the text is only justified on the left; the right margin is ragged. The command is written on a line of its own, without braces. The @raggedright command is ended by @end raggedright on a line of its own. This command has no effect in Info and HTML output, where text is always set ragged right.

The @raggedright command can be useful with paragraphs containing lists of commands with long names, when it is known in advance that justifying the text on both margins will make the paragraph look bad.

An example (from elsewhere in this manual):

@raggedright
Commands for double and single angle quotation marks:
@code{@@guillemetleft@{@}}, @code{@@guillemetright@{@}},
@code{@@guillemotleft@{@}}, @code{@@guillemotright@{@}},
@code{@@guilsinglleft@{@}}, @code{@@guilsinglright@{@}}.
@end raggedright

produces

Commands for double and single angle quotation marks: @guillemetleft{}, @guillemetright{}, @guillemotleft{}, @guillemotright{}, @guilsinglleft{}, @guilsinglright{}.


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8.12 @noindent: Omitting Indentation

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 @noindent at the beginning of a line, preceding the continuation text. You can also disable indentation for all paragraphs globally with @paragraphindent (see section @paragraphindent: Controlling Paragraph Indentation).

Here is an example showing how to eliminate the normal indentation of the text after an @example, a common situation:

@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.

produces:

This is an example
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.

The standard usage of @noindent is just as above: at the beginning of what would otherwise be a paragraph, to eliminate the indentation that normally happens there. It can either be followed by text or be on a line by itself. There is no reason to use it in other contexts, such as in the middle of a paragraph or inside an environment (see section Quotations and Examples).

You can control the number of blank lines in the Info file output by adjusting the input as desired: a line containing just @noindent does not generate a blank line, and neither does an @end line for an environment.

Do not put braces after a @noindent command; they are not used, since @noindent is a command used outside of paragraphs (see section @-Command Syntax).


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8.13 @indent: Forcing Indentation

To complement the @noindent command (see the previous section), Texinfo provides the @indent command to force a paragraph to be indented. For instance, this paragraph (the first in this section) is indented using an @indent command.

And indeed, the first paragraph of a section is the most likely place to use @indent, to override the normal behavior of no indentation there (see section @paragraphindent: Controlling Paragraph Indentation). It can either be followed by text or be on a line by itself.

As a special case, when @indent is used in an environment where text is not filled, it produces a paragraph indentation space in the TeX output. (These environments are where a line of input produces a line of output, such as @example and @display; for a summary of all environments, see section Block Enclosing Commands.)

Do not put braces after an @indent command; they are not used, since @indent is a command used outside of paragraphs (see section @-Command Syntax).


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8.14 @cartouche: Rounded Rectangles

In a printed manual, the @cartouche command draws a box with rounded corners around its contents. In HTML, a normal rectangle is drawn. @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,

@cartouche
@example
% pwd
/usr/local/share/emacs
@end example
@end cartouche

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 @cartouche had no effect):

% pwd
/usr/local/share/emacs

@cartouche also implies @group (see section @group: Prevent Page Breaks).


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8.15 @small… Block Commands

In addition to the regular @example and similar commands, Texinfo has “small” example-style commands. These are @smallquotation, @smallindentedblock, @smalldisplay, @smallexample, @smallformat, and @smalllisp.

In Info output, the @small… commands are equivalent to their non-small companion commands.

In TeX, however, the @small… commands typeset text in a smaller font than the non-small example commands. Thus, for instance, code examples can contain longer lines and still fit on a page without needing to be rewritten.

A smaller font size is also requested in HTML output, and (as usual) retained in the Texinfo XML transliteration.

Mark the end of a @small… block with a corresponding @end small…. For example, pair @smallexample with @end smallexample.

Here is an example of the font used by the @smallexample command (in Info, the output will be the same as usual):

… 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.

The @small… commands use the same font style as their normal counterparts: @smallexample and @smalllisp use a fixed-width font, and everything else uses the regular font. They also have the same behavior in other respects—whether filling is done and whether margins are narrowed.

As a general rule, a printed document looks better if you use only one of (for instance) @example or @smallexample consistently within a chapter.


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9 Lists and Tables

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.


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9.1 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.

Numbered lists and tables begin with the appropriate @-command at the beginning of a line, and end with the corresponding @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.

Begin an enumerated list, for example, with an @enumerate command and end the list with an @end enumerate command. Begin an itemized list with an @itemize command, followed on the same line by a formatting command such as @bullet, and end the list with an @end itemize command.

Precede each element of a list with an @item or @itemx command.


Here is an itemized list of the different kinds of table and lists:


Here is an enumerated list with the same items:

  1. Itemized lists with and without bullets.
  2. Enumerated lists, using numbers or letters.
  3. Two-column tables with highlighting.

And here is a two-column table with the same items and their @-commands:

@itemize

Itemized lists with and without bullets.

@enumerate

Enumerated lists, using numbers or letters.

@table
@ftable
@vtable

Two-column tables, optionally with indexing.


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9.2 @itemize: Making an Itemized List

The @itemize command produces a sequence of “items”, each starting with a bullet or other mark inside the left margin, and generally indented.

Begin an itemized list by writing @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 use @bullet after @itemize, but you can use @minus, or any command or character that results in a single character in the Info file. (When you write the mark command such as @bullet after an @itemize command, you may omit the ‘{}’.) If you don’t specify a mark command, the default is @bullet. If you don’t want any mark at all, but still want logical items, use @w{} (in this case the braces are required).

After the @itemize, write your items, each starting with @item. Text can follow on the same line as the @item. The text of an item can continue for more than one paragraph.

There should be at least one @item inside the @itemize environment. If none are present, makeinfo gives a warning. If you just want indented text and not a list of items, use @indentedblock; see section @indentedblock: Indented text blocks.

Index entries and comments that are given before an @item including the first, are automatically moved (internally) to after the @item, so the output is as expected. Historically this has been a common practice.

Usually, you should put a blank line between items. This puts a blank line in the Info file. (TeX inserts the proper vertical space in any case.) Except when the entries are very brief, these blank lines make the list look better.

Here is an example of the use of @itemize, followed by the output it produces. @bullet produces an ‘*’ in Info and a round dot in other output formats.

@itemize @bullet
@item
Some text for foo.

@item
Some text
for bar.
@end itemize

This produces:

Itemized lists may be embedded within other itemized lists. Here is a list marked with dashes embedded in a list marked with bullets:

@itemize @bullet
@item
First item.

@itemize @minus
@item
Inner item.

@item
Second inner item.
@end itemize

@item
Second outer item.
@end itemize

This produces:


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9.3 @enumerate: Making a Numbered or Lettered List

@enumerate is like @itemize (see section @itemize: Making an Itemized List), except that the labels on the items are successive integers or letters instead of bullets.

Write the @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, @enumerate starts the list with the number ‘1’. With a numeric argument, such as ‘3’, the command starts the list with that number. With an upper- or lowercase letter, such as ‘a’ or ‘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 @item at the beginning of each item in the enumeration. It is ok to have text following the @item, and the text for an item can continue for several paragraphs.

You should put a blank line between entries in the list. This generally makes it easier to read the Info file.

Here is an example of @enumerate without an argument:

@enumerate
@item
Underlying causes.

@item
Proximate causes.
@end enumerate

This produces:

  1. Underlying causes.
  2. Proximate causes.

Here is an example with an argument of 3:


@enumerate 3
@item
Predisposing causes.

@item
Precipitating causes.

@item
Perpetuating causes.
@end enumerate

This produces:

  1. Predisposing causes.
  2. Precipitating causes.
  3. Perpetuating causes.

Here is a brief summary of the alternatives. The summary is constructed using @enumerate with an argument of a.


  1. @enumerate

    Without an argument, produce a numbered list, with the first item numbered 1.

  2. @enumerate unsigned-integer

    With an (unsigned) numeric argument, start a numbered list with that number. You can use this to continue a list that you interrupted with other text.

  3. @enumerate upper-case-letter

    With an uppercase letter as argument, start a list in which each item is marked by a letter, beginning with that uppercase letter.

  4. @enumerate lower-case-letter

    With a lowercase letter as argument, start a list in which each item is marked by a letter, beginning with that lowercase letter.

You can also nest enumerated lists, as in an outline.


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9.4 Making a Two-column Table

@table is similar to @itemize (see section @itemize: Making an Itemized List), but allows you to specify a name or heading line for each item. The @table command is used to produce two-column tables, and is especially useful for glossaries, explanatory exhibits, and command-line option summaries.


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9.4.1 Using the @table Command

Use the @table command to produce a two-column table. This command is typically used when you have a list of items and a brief text with each one, such as a list of definitions.

Write the @table command at the beginning of a line, after a blank line, and follow it on the same line with an argument that is an ‘indicating’ command, such as @code, @samp, @var, @option, or @kbd (see section Indicating Definitions, Commands, etc.). This command will be applied to the text in the first column. For example, @table @code will cause the text in the first column to be output as if it had been the argument to a @code command.

You may use the @asis command as an argument to @table. @asis is a command that does nothing: if you use this command after @table, the first column entries are output without added highlighting (“as is”).

The @table command works with other commands besides those explicitly mentioned here. However, you can only use predefined Texinfo commands that take an argument in braces. You cannot reliably use a new command defined with @macro, although an @alias (for a suitable predefined command) is acceptable. See section Defining New Texinfo Commands.

Begin each table entry with an @item command at the beginning of a line. Write the text for the first column on the same line as the @item command. Write the text for the second column on the line following the @item line and on subsequent lines. 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 @item will be placed in the first column (including any footnotes). You do not need to type anything for an empty second column.

Normally, you should put a blank line before an @item line (except the first one). 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 @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.

For example, the following table highlights the text in the first column with the @samp command:

@table @samp
@item foo
This is the text for
@samp{foo}.

@item bar
Text for @samp{bar}.
@end table

This produces:

foo

This is the text for ‘foo’.

bar

Text for ‘bar’.

If you want to list two or more named items with a single block of text, use the @itemx command. (See section @itemx: Second and Subsequent Items.)

The @table command (see section Using the @table Command) is not supported inside @display. Since @display is line-oriented, it doesn’t make sense to use them together. If you want to indent a table, try @quotation (see section @quotation: Block Quotations) or @indentedblock (see section @indentedblock: Indented text blocks).


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9.4.2 @ftable and @vtable

The @ftable and @vtable commands are the same as the @table command except that @ftable automatically enters each of the items in the first column of the table into the index of functions and @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 @item or @itemx commands are indexed, and they are indexed in exactly the form that they appear on that line. See section Indices, for more information about indices.

Begin a two-column table using @ftable or @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, exactly as you would for a @table command; and end the table with an @end ftable or @end vtable command on a line by itself.

See the example for @table in the previous section.


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9.4.3 @itemx: Second and Subsequent Items

Use the @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 @item for the first entry, and @itemx for all subsequent entries; @itemx must always follow an @item command, with no blank line intervening.

The @itemx command works exactly like @item except that it does not generate extra vertical space above the first column text. If you have multiple consecutive @itemx commands, do not insert any blank lines between them.

For example,

@table @code
@item upcase
@itemx downcase
These two functions accept a character or a string as
argument, and return the corresponding uppercase (lowercase)
character or string.
@end table

This produces:

upcase
downcase

These two functions accept a character or a string as argument, and return the corresponding uppercase (lowercase) character or string.

(Note also that this example illustrates multi-line supporting text in a two-column table.)


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9.5 @multitable: Multi-column Tables

@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 @multitable line itself, and write each row of the actual table following an @item command, with columns separated by a @tab command. Finally, @end multitable completes the table. Details in the sections below.


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9.5.1 Multitable Column Widths

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 @multitable command.

  1. To specify column widths as fractions of the line length, write @columnfractions and the decimal numbers (presumably less than 1; a leading zero is allowed and ignored) after the @multitable command, as in:
    @multitable @columnfractions .33 .33 .33
    

    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.

  2. To specify a prototype row, write the longest entry for each column enclosed in braces after the @multitable command. For example:
    @multitable {some text for column one} {for column two}
    

    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 are particularly likely to be useful.


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9.5.2 Multitable Rows

After the @multitable command defining the column widths (see the previous section), you begin each row in the body of a multitable with @item, and separate the column entries with @tab. Line breaks are not special within the table body, and you may break input lines in your source file as necessary.

You can also use @headitem instead of @item to produce a heading row. The TeX output for such a row is in bold, and the HTML and Docbook output uses the <thead> tag. In Info, the heading row is followed by a separator line made of dashes (‘-’ characters).

The command @headitemfont can be used in templates when the entries in a @headitem row need to be used in a template. It is a synonym for @b, but using @headitemfont avoids any dependency on that particular font style, in case we provide a way to change it in the future.

Here is a complete example of a multi-column table (the text is from The GNU Emacs Manual, see Splitting Windows in The GNU Emacs Manual):

@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

produces:

KeyCommandDescription
C-x 2split-window-verticallySplit the selected window into two windows, with one above the other.
C-x 3split-window-horizontallySplit the selected window into two windows positioned side by side.
C-Mouse-2In the mode line or scroll bar of a window, split that window.

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10 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.


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10.1 Floats

A float is a display which is set off from the main text. It is typically labeled as being a “Figure”, “Table”, “Example”, or some similar type.

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 @group (see section @group: Prevent Page Breaks).


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10.1.1 @float [type][,label]: Floating Material

To produce floating material, enclose the material you want to be displayed separate between @float and @end float commands, on lines by themselves.

Floating material often uses @image to display an already-existing graphic (see section Inserting Images), or @multitable to display a table (see section @multitable: Multi-column Tables). However, the contents of the float can be anything. Here’s an example with simple text:

@float Figure,fig:ex1
This is an example float.
@end float

And the output:

This is an example float.

Figure 10.1

As shown in the example, @float takes two arguments (separated by a comma), type and label. Both are optional.

type

Specifies the sort of float this is; typically a word such as “Figure”, “Table”, etc. If this is not given, and label is, any cross-referencing will simply use a bare number.

label

Specifies a cross-reference label for this float. If given, this float is automatically given a number, and will appear in any @listoffloats output (see section @listoffloats: Tables of Contents for Floats). Cross references to label are allowed.

On the other hand, if label is not given, then the float will not be numbered and consequently will not appear in the @listoffloats output or be cross-referenceable.

Ordinarily, you specify both type and label, to get a labeled and numbered float.

In Texinfo, all floats are numbered in the same way: with the chapter number (or appendix letter), a period, and the float number, which simply counts 1, 2, 3, …, and is reset at each chapter. Each float type is counted independently.

Floats within an @unnumbered, or outside of any chapter, are simply numbered consecutively from 1.

These numbering conventions are not, at present, changeable.


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10.1.2 @caption & @shortcaption

You may write a @caption anywhere within a @float environment, to define a caption for the float. It is not allowed in any other context. @caption takes a single argument, enclosed in braces. Here’s an example:

@float
An example float, with caption.
@caption{Caption for example float.}
@end float

The output is:

An example float, with caption.

Caption for example float.

@caption can appear anywhere within the float; it is not processed until the @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 @float command (see the previous section).

The @shortcaption command likewise may be used only within @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:

@float
... as above ...
@shortcaption{Text for list of floats.}
@end float

The text for @shortcaption may not contain comments (@c), verbatim text (@verb), environments such as @example, footnotes (@footnote) or other complex constructs. The same constraints apply to @caption unless there is a @shortcaption.


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10.1.3 @listoffloats: Tables of Contents for Floats

You can write a @listoffloats command to generate a list of floats for a given float type (see section @float [type][,label]: Floating Material), analogous to the document’s overall table of contents. Typically, it is written in its own @unnumbered node to provide a heading and structure, rather like @printindex (see section Printing Indices and Menus).

@listoffloats takes one optional argument, the float type. Here’s an example:

@node List of Figures
@unnumbered List of Figures
@listoffloats Figure

And here’s what the output from @listoffloats looks like, given the example figure earlier in this chapter (the Info output is formatted as a menu):

Figure 10.1

Without any argument, @listoffloats generates a list of floats for which no float type was specified, i.e., no first argument to the @float command (see section @float [type][,label]: Floating Material).

Each line in the list of floats contains the float type (if any), the float number, and the caption, if any—the @shortcaption argument, if it was specified, else the @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.


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10.2 Inserting Images

You can insert an image given in an external file with the @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.


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10.2.1 Image Syntax

Here is the synopsis of the @image command:

@image{filename[, width[, height[, alttext[, extension]]]]}

The filename argument is mandatory, and must not have an extension, because the different processors support different formats:

If you want to install image files for use by Info readers too, we recommend putting them in a subdirectory like ‘foo-figures’ for a package foo. Copying the files into $(infodir)/foo-figures/ should be done in your Makefile.

The width and 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 @center (see section @titlefont, @center, and @sp).

For HTML output, makeinfo sets the alt attribute for inline images to the optional alttext (fourth) argument to @image, if supplied. If not supplied, makeinfo uses the full file name of the image being displayed. The alttext is processed as Texinfo text, so special characters such as ‘"’ and ‘<’ and ‘&’ are escaped in the HTML output; also, you can get an empty alt string with @- (a command that produces no output; see section @- and @hyphenation: Helping TeX Hyphenate).

For Info output, the alt string is also processed as Texinfo text and output. In this case, ‘\’ is escaped as ‘\\’ and ‘"’ as ‘\"’; no other escapes are done.

In Info output, makeinfo writes a reference to the binary image file (trying filename suffixed with ‘extension’, ‘.extension’, ‘.png’, or ‘.jpg’, in that order) if one exists. It also literally includes the ‘.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.

The implementation of this is to put the following construct into the Info output:

^@^H[image src="binaryfile" text="txtfile"
           alt="alttext ... ^@^H]

where ‘^@’ and ‘^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.


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10.2.2 Image Scaling

The optional width and height arguments to the @image command (see the previous section) specify the size to which to scale the image. They are only taken into account in TeX. 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 likely distorting the original image by changing its aspect ratio.

The width and height may be specified using any valid TeX dimension, namely:

pt

point (72.27pt = 1in)

pc

pica (1pc = 12pt)

bp

big point (72bp = 1in)

in

inch

cm

centimeter (2.54cm = 1in)

mm

millimeter (10mm = 1cm)

dd

didôt point (1157dd = 1238pt)

cc

cicero (1cc = 12dd)

sp

scaled point (65536sp = 1pt)

For example, the following will scale a file ‘ridt.eps’ to one inch vertically, with the width scaled proportionately:

@image{ridt,,1in}

For @image to work with TeX, the file ‘epsf.tex’ must be installed somewhere that TeX can find it. (The standard location is ‘texmf/tex/generic/dvips/epsf.tex’, where texmf is a root of your TeX directory tree.) This file is included in the Texinfo distribution and is also available from ftp://tug.org/tex/epsf.tex, among other places.

@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.


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10.3 Footnotes

A footnote is for a reference that documents or elucidates the primary text.(4)

Footnotes are distracting; use them sparingly at most, and it is best to avoid them completely. Standard bibliographical references are usually better placed in a bibliography at the end of a document instead of in footnotes throughout.


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10.3.1 Footnote Commands

In Texinfo, footnotes are created with the @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:

ordinary text@footnote{text of footnote}

As shown here, the @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(5); in the Texinfo source, it looks like this:

…a sample footnote@footnote{Here is the sample
footnote.}; in the Texinfo source…

As you can see, this source includes two punctuation marks next to each other; in this case, ‘.};’ 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. (Another style, perfectly acceptable, is to put the footnote after punctuation belonging to the sentence, as in ‘;@footnote{...’.)

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: ‘(1)’. The reference mark is followed by a cross-reference link to the footnote text if footnotes are put in separate nodes (see section Footnote Styles).

In the HTML output, footnote references are generally marked with a small, superscripted number which is rendered as a hypertext link to the footnote text.

Footnotes cannot be nested, and cannot appear in section headings of any kind or other “unusual” places.

A final tip: footnotes in the argument of an @item command for an @table must be entirely on the same line as the @item (as usual). See section Making a Two-column Table.


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10.3.2 Footnote Styles

Info has two footnote styles, which determine where the text of the footnote is located:

Unless your document has long and important footnotes (as in, say, Gibbon’s Decline and Fall …), we recommend the ‘end’ style, as it is simpler for readers to follow.

Use the @footnotestyle command to specify an Info file’s footnote style. Write this command at the beginning of a line followed by an argument, either ‘end’ for the end node style or ‘separate’ for the separate node style.

For example,

@footnotestyle end

or

@footnotestyle separate

Write a @footnotestyle command before or shortly after the end-of-header line at the beginning of a Texinfo file. (You should include any @footnotestyle command between the start-of-header and end-of-header lines, so the region formatting commands will format footnotes as specified.)

In HTML, when the footnote style is ‘end’, or if the output is not split, footnotes are put at the end of the output. If set to ‘separate’, and the output is split, they are placed in a separate file.


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11 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.


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11.1 Predefined Indices

Texinfo provides six predefined indices. Here are their nominal meanings, abbreviations, and the corresponding index entry commands:

cp

(@cindex) concept index, for general concepts.

fn

(@findex) function index, for function and function-like names (such as entry points of libraries).

ky

(@kindex) keystroke index, for keyboard commands.

pg

(@pindex) program index, for names of programs.

tp

(@tindex) data type index, for type names (such as structures defined in header files).

vr

(@vindex) variable index, for variable names (such as global variables of libraries).

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 @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 (see section Defining 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 @synindex or @syncodeindex commands (see section Combining Indices).


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11.2 Defining the Entries of an Index

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.

An index entry consists of an indexing command at the beginning of a line followed, on the rest of the line, by the entry.

For example, this section begins with the following five entries for the concept index:

@cindex Defining indexing entries
@cindex Index entries, defining
@cindex Entries for an index
@cindex Specifying index entries
@cindex Creating index entries

Each predefined index has its own indexing command—@cindex for the concept index, @findex for the function index, and so on, as listed in the previous section.

Index entries should precede the visible material that is being indexed. For instance:

@cindex hello
Hello, there!

Among other reasons, that way following indexing links (in whatever context) ends up before the material, where readers want to be, instead of after.

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 font. You may change the way part of an entry is printed with the usual Texinfo commands, such as @file for file names (see section Marking Text, Words and Phrases), and @r for the normal roman font (see section Fonts for Printing).

For the printed output, you may specify an explicit sort key for an index entry using @sortas immediately following the index command. For example: ‘@findex @sortas{\} \ @r{(literal \ in @code{@@math})’ sorts the index entry this produces under backslash.

To reduce the quantity of sort keys you need to provide explicitly, you may choose to ignore certain characters in index entries for the purposes of sorting. The characters that you can currently choose to ignore are ‘\’, ‘-’, ‘<’ and ‘@’, which are ignored by giving as an argument to the @set command, respectively, txiindexbackslashignore, txiindexhyphenignore, txiindexlessthanignore and txiindexatsignignore. For example, specifying ‘@set txiindexbackslashignore’ causes the ‘\mathopsup’ entry in the index for this manual to be sorted as if it were ‘mathopsup’, so that it appears among the other entries beginning ‘M’.

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. See section The Parts of a Menu, for more information about the structure of a menu entry.


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11.3 Making Index Entries

Concept index entries consist of text. The best way to write an index is to devise entries which are terse yet clear. If you can do this, the index usually looks better if the entries are written just as they would appear in the middle of a sentence, that is, capitalizing only proper names and acronyms that always call for uppercase 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. Whichever case convention you use, use it consistently.

In any event, do not ever capitalize a case-sensitive name such as a C or Lisp function name or a shell command; that would be a spelling error. Entries in indices other than the concept index are symbol names in programming languages, or program names; these names are usually case-sensitive, so likewise use upper- and lowercase as required.

It is a good idea to make index entries unique wherever feasible. That way, people using the printed output or online completion of index entries don’t see undifferentiated lists. Consider this an opportunity to make otherwise-identical index entries be more specific, so readers can more easily find the exact place they are looking for.

When you are making index entries, it is good practice to think of the different ways people may look for something. Different people 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 “Indices” are 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.

Like typesetting, the construction of an index is a skilled art, the subtleties of which may not be appreciated until you need to do it yourself.


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11.4 Printing Indices and Menus

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 @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 @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 texindex (see section Formatting and Printing 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. See section 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 @printindex command.

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

For example:

@node Variable Index
@unnumbered Variable Index

@printindex vr
@node Concept Index
@unnumbered Concept Index

@printindex cp

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


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11.5 Combining Indices

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 @cindex commands for them instead of @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.


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11.5.1 @syncodeindex: Combining indices using @code

When you want to combine functions and concepts into one index, you should index the functions with @findex and index the concepts with @cindex, and use the @syncodeindex command to redirect the function index entries into the concept index.

The @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:

@syncodeindex from to

For this purpose, the indices are given two-letter names:

cp

concept index

fn

function index

vr

variable index

ky

key index

pg

program index

tp

data type index

Write a @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:

@syncodeindex fn cp

This will cause all entries designated for the function index to merge in with the concept index instead.

To merge both a variables index and a function index into a concept index, write the following:

@syncodeindex vr cp
@syncodeindex fn cp

The @syncodeindex command puts all the entries from the ‘from’ index (the redirected index) into the @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 font as you would expect.


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11.5.2 @synindex: Combining indices

The @synindex command is nearly the same as the @syncodeindex command, except that it does not put the ‘from’ index entries into the @code font; rather it puts them in the roman font. Thus, you use @synindex when you merge a concept index into a function index.

See section Printing Indices and Menus, for information about printing an index at the end of a book or creating an index menu in an Info file.


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11.6 Defining New Indices

In addition to the predefined indices (see section Predefined Indices), you may use the @defindex and @defcodeindex commands to define new indices. These commands create new indexing @-commands with which you mark index entries. The @defindex command is used like this:

@defindex name

New index names are usually two-letter words, such as ‘au’. For example:

@defindex au

This defines a new index, called the ‘au’ index. At the same time, it creates a new indexing command, @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 ‘au’ index entries.

@section Cognitive Semantics
@cindex kinesthetic image schemas
@auindex Johnson, Mark
@auindex Lakoff, George

(Evidently, ‘au’ serves here as an abbreviation for “author”.)

Texinfo constructs the new indexing command by concatenating the name of the index with ‘index’; thus, defining an ‘xy’ index leads to the automatic creation of an @xyindex command.

Use the @printindex command to print the index, as you do with the predefined indices. For example:

@node Author Index
@unnumbered Author Index

@printindex au

The @defcodeindex is like the @defindex command, except that, in the printed output, it prints entries in an @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 @synindex or @syncodeindex commands (see section Texinfo File Header).

As mentioned earlier (see section Predefined 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.

When creating an index, TeX creates a file whose extension is the name of the index (see Names of index files). Therefore you should avoid using index names that collide with extensions used for other purposes, such as ‘.aux’ or ‘.xml’. makeinfo already reports an error if a new index conflicts well-known extension name.


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12 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.


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12.1 Special Characters: Inserting @ {} , \ #

@’ and curly braces are the basic special characters in Texinfo. To insert these characters so they appear in text, you must put an ‘@’ in front of these characters to prevent Texinfo from misinterpreting them. Alphabetic commands are also provided.

The other characters (comma, backslash, hash) are special only in restricted contexts, as explained in the respective sections.


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12.1.1 Inserting ‘@’ with @@ and @atchar{}

@@ produces a single ‘@’ character in the output. Do not put braces after an @@ command.

@atchar{} also produces a single ‘@’ character in the output. It does need following braces, as usual for alphabetic commands. In inline conditionals (see section Inline Conditionals: @inline, @inlineifelse, @inlineraw), it can be necessary to avoid using the literal ‘@’ character in the source (and may be clearer in other contexts).


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12.1.2 Inserting ‘{ ‘}’ with @{ @} and @l rbracechar{}

@{ produces a single ‘{’ in the output, and @} produces a single ‘}’. Do not put braces after either an @{ or an @} command.

@lbracechar{} and @rbracechar{} also produce single ‘{’ and ‘}’ characters in the output. They do need following braces, as usual for alphabetic commands. In inline conditionals (see section Inline Conditionals: @inline, @inlineifelse, @inlineraw), it can be necessary to avoid using literal brace characters in the source (and may be clearer in other contexts).


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12.1.3 Inserting ‘,’ with @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 only in one context: to separate arguments to those Texinfo commands, such as @acronym (see section @acronym{acronym[, meaning]}) and @xref (see section Cross-references), as well as user-defined macros (see section Defining Macros), which take more than one argument.

Since a comma character would confuse Texinfo’s parsing for these commands, you must use the command ‘@comma{}’ instead if you want to pass an actual comma. Here are some examples:

@acronym{ABC, A Bizarre @comma{}}
@xref{Comma,, The @comma{} symbol}
@mymac{One argument@comma{} containing a comma}

Although ‘@comma{}’ can be used nearly anywhere, there is no need for it anywhere except in this unusual case.

(Incidentally, the name ‘@comma’ lacks the ‘char’ suffix used in its companion commands only for historical reasons. It didn’t seem important enough to define a synonym.)


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12.1.4 Inserting ‘\’ with @backslashchar{}

Ordinarily, a backslash ‘\’ is a normal character in Texinfo that can be simply typed in your input where you need it. The result is to typeset the backslash from the typewriter font.

However, Texinfo uses the backslash as a special character in one restricted context: to delimit formal arguments in the bodies of user-defined macros (see section Defining Macros).

Due to the vagaries of macro argument parsing, it is more reliable to pass an alphabetic command that produces a backslash instead of using a literal \. Hence @backslashchar{}. Here is an example macro call:

@mymac{One argument@backslashchar{} with a backslash}

Texinfo documents may also use \ as a command character inside @math (see section @math: Inserting Mathematical Expressions). In this case, @\ or \backslash produces a “math” backslash (from the math symbol font), while @backslashchar{} produces a typewriter backslash as usual.

Although ‘@backslashchar{}’ can be used nearly anywhere, there is no need for it except in these unusual cases.


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12.1.5 Inserting ‘#’ with @hashchar{}

Ordinarily, a hash ‘#’ is a normal character in Texinfo that can be simply typed in your input where you need it. The result is to typeset the hash character from the current font.

This character has many other names, varying by locale, such as “number sign”, “pound”, and “octothorp”. It is also sometimes called “sharp” or “sharp sign” since it vaguely resembles the musical symbol by that name. In situations where Texinfo is used, “hash” is the most common in our experience.

However, Texinfo uses the hash character as a special character in one restricted context: to introduce the so-called #line directive and variants (see section External Macro Processors: Line Directives).

So, in order to typeset an actual hash character in such a place (for example, in a program that needs documentation about #line), it’s necessary to use @hashchar{} or some other construct. Here’s an example:

@hashchar{} 10 "example.c"

Although ‘@hashchar{}’ can be used nearly anywhere, there is no need for it anywhere except this unusual case.


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12.2 Inserting Quote Characters

As explained in the early section on general Texinfo input conventions (see section General Syntactic Conventions), Texinfo source files use the ASCII character ` (96 decimal) to produce a left quote (‘), and ASCII ' (39 decimal) to produce a right quote (’). Doubling these input characters (`` and '') 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 xpdf works fine, but other PDF readers, both free and nonfree, have problems.)

If this is a concern for you, Texinfo provides these two commands:

@codequoteundirected on-off

causes the output for the ' character in code environments to be the undirected single quote, like this: '.

@codequotebacktick on-off

causes the output for the ` character in code environments to be the backtick character (standalone grave accent), like this: `.

If you want these settings for only part of the document, @codequote... off will restore the normal behavior, as in @codequoteundirected off.

These settings affect @code, @example, @kbd, @samp, @verb, and @verbatim. See section Highlighting Commands are Useful.

This feature used to be controlled by using @set to change the values of the corresponding variables txicodequoteundirected and txicodequotebacktick; they are still supported, but the command interface is preferred.


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12.3 Inserting Space

The following sections describe commands that control spacing of various kinds within and after sentences.


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12.3.1 Multiple Spaces

Ordinarily, multiple whitespace characters (space, tab, and newline) are collapsed into a single space.

Occasionally, you may want to produce several consecutive spaces, either for purposes of example (e.g., what your program does with multiple spaces as input), or merely for purposes of appearance in headings or lists. Texinfo supports three commands: @SPACE, @TAB, and @NL, all of which insert a single space into the output. (Here, @SPACE represents an ‘@’ character followed by a space, i.e., ‘@ ’, TAB represents an actual tab character, and @NL represents an ‘@’ character and end-of-line, i.e., when ‘@’ is the last character on a line.)

For example,

Spacey@ @ @ @
example.

produces

Spacey    example.

Other possible uses of @SPACE have been subsumed by @multitable (see section @multitable: Multi-column Tables).

Do not follow any of these commands with braces.

To produce a non-breakable space, see @tie{}: Inserting an Unbreakable Space.


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12.3.2 Not Ending a Sentence

When a period, exclamation point or question mark is at the end of a sentence, slightly more space is inserted after it in a typeset manual.

Usually, Texinfo can determine automatically when a period ends a sentence. However, special commands are needed in some circumstances. Use the @: command after a period, question mark, exclamation mark or colon that should not be followed by extra space. This is necessary in the following situations:

  1. After a period that ends a lowercase abbreviation which is not at the end of a sentences.
  2. When a parenthetical remark in the middle of a sentence (like this one!) ends with a period, exclamation point or question mark, @: should be used after the right parenthesis. Similarly for right brackets and right quotes (both single and double).

For example:

foo vs.@: bar (or?)@: baz’,

The first line below shows the output, and for comparison, the second line shows the spacing when the ‘@:’ commands were not used.

foo vs. bar (or?) baz
foo vs. bar (or?) baz

It may help you to remember what @: does by imagining that it stands for an invisible lower-case character that stops a word ending in a period.

A few Texinfo commands force normal interword spacing, so that you don’t have to insert @: where you otherwise would. These are the code-like highlighting commands, @var, @abbr, and @acronym (see section Highlighting Commands are Useful). For example, in ‘@code{foo. bar}’ the period is not considered to be the end of a sentence, and no extra space is inserted.

@: has no effect on the HTML or Docbook output.


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12.3.3 Ending a Sentence

As mentioned above, Texinfo normally inserts additional space after the end of a sentence. It uses the same heuristic for this as TeX: a sentence ends with a period, exclamation point, or question mark, either preceded or followed by optional closing punctuation, and then whitespace, and not preceded by a capital letter.

Use @. instead of a period, @! instead of an exclamation point, and @? instead of a question mark at the end of a sentence that does end with a capital letter. Do not put braces after any of these commands. For 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.

The output follows. In printed output and Info, you can see the desired extra whitespace after the ‘W’ in the first line.

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.

In the HTML output, @. is equivalent to a simple ‘.’; likewise for @! and @?.

The “closing punctuation” mentioned above is defined as a right parenthesis (‘)’, right bracket (‘]’), or right quote, either single or double (‘'’ and ‘''’; the many possible additional Unicode right quotes are not included). These characters can be thought of as invisible with respect to whether a given period ends a sentence. (This is the same rule as TeX.) For instance, the periods in ‘foo.) Bar’ and ‘foo.'' Bar’ do end sentences.

The meanings of @: and @., etc. in Texinfo are designed to work well with the Emacs sentence motion commands (see Sentences in The GNU Emacs Manual). It may help to imagine that the ‘@’ in ‘@.’, etc., is an invisible lower-case letter ‘a’ which makes an upper-case letter before it immaterial for the purposes of deciding whether the period ends the sentence.

A few Texinfo commands are not considered as being an abbreviation, even though they may end with a capital letter when expanded, so that you don’t have to insert @. and companions. Notably, this is the case for code-like highlighting commands, @var arguments ending with a capital letter, @LaTeX, and @TeX. For example, that sentence ended with ‘... @code{@@TeX}.’; @. was not needed. Similarly, in ... @var{VARNAME}. Text the period after VARNAME ends the sentence; there is no need to use @..


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12.3.4 @frenchspacing val: Control Sentence Spacing

In American typography, it is traditional and correct to put extra space at the end of a sentence. This is the default in Texinfo (implemented in Info and printed output; for HTML, we don’t try to override the browser). In French typography (and others), this extra space is wrong; all spaces are uniform.

Therefore Texinfo provides the @frenchspacing command to control the spacing after punctuation. It reads the rest of the line as its argument, which must be the single word ‘on’ or ‘off’ (always these words, regardless of the language of the document). Here is an example:

@frenchspacing on
This is text. Two sentences. Three sentences. French spacing.

@frenchspacing off
This is text. Two sentences. Three sentences. Non-French spacing.

produces:

This is text. Two sentences. Three sentences. French spacing.

This is text. Two sentences. Three sentences. Non-French spacing.

@frenchspacing also affects the output after @., @!, and @? (see section Ending a Sentence).

@frenchspacing has no effect on the HTML or Docbook output; for XML, it outputs a transliteration of itself (see section Output Formats).


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12.3.5 @dmn{dimension}: Format a Dimension

You can use the @dmn command to format a dimension with a little extra space in the printed output. That is, on seeing @dmn, TeX inserts just enough space for proper typesetting; in other output formats, the formatting commands insert no space at all.

To use the @dmn command, write the number and then follow it immediately, with no intervening space, by @dmn, and then by the dimension within braces. For example,

A4 paper is 8.27@dmn{in} wide.

produces

A4 paper is 8.27in wide.

Not everyone uses this style. Some people prefer ‘8.27 in.’ or ‘8.27 inches’. In these cases, however, you need to use @tie (see section @tie{}: Inserting an Unbreakable Space) or @w (see section @w{text}: Prevent Line Breaks) so that no line break can occur between the number and the dimension. Also, if you write a period after an abbreviation within a sentence (as with the ‘in.’ above), you should write ‘@:’ after the period to prevent TeX from inserting extra whitespace, as shown here. See section Not Ending a Sentence.


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12.4 Inserting Accents

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 (@'{e}), or, as a special case, the braces can be omitted, in which case the argument is the next character (@'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 @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 @', then there must not be a space; the argument is the very next character.

Exception: the argument to @tieaccent must be enclosed in braces (since it is two characters instead of one).

To get the true accented characters output in Info, not just the ASCII transliterations, it is necessary to specify @documentencoding with an encoding which supports the required characters (see section @documentencoding enc: Set Input Encoding). In this case, you can also use non-ASCII (e.g., pre-accented) characters in the source file.

CommandOutputWhat
@"oöumlaut accent
@’oóacute accent
@,{c}çcedilla accent
@=oōmacron/overbar accent
@^oôcircumflex accent
@‘oògrave accent
@~oõtilde accent
@dotaccent{o}ȯoverdot accent
@H{o}őlong Hungarian umlaut
@ogonek{a}ąogonek
@ringaccent{o}o*ring accent
@tieaccent{oo}oo[tie-after accent
@u{o}ŏbreve accent
@ubaraccent{o}o_underbar accent
@udotaccent{o}underdot accent
@v{o}o<caron/hacek/check accent

This table lists the Texinfo commands for inserting other characters commonly used in languages other than English.

@exclamdown{}¡upside-down !
@questiondown{}¿upside-down ?
@aa{} @AA{}å Åa,A with circle
@ae{} @AE{}æ Æae,AE ligatures
@dh{} @DH{}ð ÐIcelandic eth
@dotless{i}idotless i
@dotless{j}jdotless j
@l{} @L{}ł Łsuppressed-L,l
@o{} @O{}ø ØO,o with slash
@oe{} @OE{}œ Œoe,OE ligatures
@ordf{} @ordm{}ª ºSpanish ordinals
@ss{}ßes-zet or sharp S
@th{} @TH{}þ ÞIcelandic thorn

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12.5 Inserting Quotation Marks

Use doubled single-quote characters to begin and end quotations: ‘‘…’’. TeX converts two single quotes to left- and right-hand doubled quotation marks, and Info converts doubled single-quote characters to ASCII double-quotes: ‘‘…’’ becomes "…".

You may occasionally need to produce two consecutive single quotes; for example, in documenting a computer language such as Maxima where ’’ is a valid command. You can do this with the input ’@w{}’; the empty @w command stops the combination into the double-quote characters.

The left quote character (, 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.

In order to get the symbols for the quotation marks in encoded Info output, it is necessary to specify @documentencoding UTF-8. (See section @documentencoding enc: Set Input Encoding.) Double guillemets are also present in ISO 8859-1 (aka Latin 1) and ISO 8859-15 (aka Latin 9).

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 (‘ecrm1000’ and other variants). These fonts are freely available, of course; you can download them from http://ctan.org/pkg/ec, among other places.

The free EC fonts are bitmap fonts created with Metafont. Especially for on-line viewing, Type 1 (vector) versions of the fonts are preferable; these are available in the CM-Super font package (http://ctan.org/pkg/cm-super).

Both distributions include installation instructions.

CommandGlyphUnicode name (point)
@quotedblleft{} ``Left double quotation mark (U+201C)
@quotedblright{} ''Right double quotation mark (U+201D)
@quoteleft{} `Left single quotation mark (U+2018)
@quoteright{} 'Right single quotation mark (U+2019)
@quotedblbase{}Double low-9 quotation mark (U+201E)
@quotesinglbase{}Single low-9 quotation mark (U+201A)
@guillemetleft{}«Left-pointing double angle quotation mark (U+00AB)
@guillemetright{}»Right-pointing double angle quotation mark (U+00BB)
@guilsinglleft{}Single left-pointing angle quotation mark (U+2039)
@guilsinglright{}Single right-pointing angle quotation mark (U+203A)

For the double angle quotation marks, Adobe and LaTeX glyph names are also supported: @guillemotleft and @guillemotright. These names are incorrect; a “guillemot” is a bird species (a type of auk).

Traditions for quotation mark usage vary to a great extent between languages (http://en.wikipedia.org/wiki/Quotation_mark). Texinfo does not provide commands or configurations 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 (see section @alias new=existing) can simplify the usage and make the source code more readable. For example, in German, @quotedblbase is used for the left double quote, and the right double quote is the glyph produced by @quotedblleft, which is counter-intuitive. Thus, in this case the following aliases would be convenient:

@alias lgqq = quotedblbase
@alias rgqq = quotedblleft

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12.6 @sub and @sup: Inserting Subscripts and Superscripts

You can insert subscripts and superscripts, in either text or math, with the @sub and @sup commands. (For other mathematical expressions, see the next section.) For example, here is a purely textual subscript and superscript:

here@sub{below}@sup{above}

produces:

here@sub{below}@sup{above}

Inside @math, @sub and @sup produce mathematical subscripts and superscripts. This uses a different font in the TeX output (math italic instead of text italic); it makes no difference in the other output formats. Here’s an example:

@math{e@sup{x}}

produces:

e@sup{x}

In Info and plain text, regardless of being used inside @math, @sub{text} is output as ‘_{text}’ and @sup{text} as ‘^{text}’, including the literal braces (to mark the beginning and end of the “script” text to the reader).

When the output format (and display program) permit (TeX math, HTML), the superscript is set above the subscript when both commands are given consecutively.


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12.7 @math: Inserting Mathematical Expressions

You can write a short mathematical expression with the @math command. Write the mathematical expression between braces, like this:

@math{(a + b) = (b + a)}

This produces the following in Info and HTML:

(a + b) = (b + a)

The @math command has no special effect on the Info and HTML output. makeinfo expands any @-commands as usual, but it does not try to use produce good mathematical formatting in any way (no use of MathML, etc.). The HTML output is enclosed by <em>...</em>, but nothing more.

However, as far as the TeX output is concerned, plain TeX mathematical commands are allowed in @math, starting with ‘\’. In essence, @math switches into plain TeX math mode. (Exception: the plain TeX command \sup, which typesets the mathematical operator name ‘sup’, must be accessed as \mathopsup, due to the conflict with Texinfo’s @sup command.)

This allows you 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.

The @sub and @sup commands described in the previous section produce subscripts and superscripts in HTML output as well as TeX; the plain TeX characters _ and ^ for subscripts and superscripts are recognized by TeX inside @math, but do nothing special in HTML or other output formats.

It’s best to use ‘\’ instead of ‘@’ for any such mathematical commands; otherwise, makeinfo will complain. On the other hand, makeinfo does allow input with matching (but unescaped) braces, such as ‘k_{75}’; it complains about such bare braces in regular input.

Here’s an example:

@math{\sin 2\pi \equiv \cos 3\pi}

which looks like the input in Info and HTML:

\sin 2\pi \equiv \cos 3\pi

Since ‘\’ is an escape character inside @math, you can use @\ to get a literal backslash (\\ will work in TeX, but you’d get the literal two characters ‘\\’ in Info). @\ is not defined outside of @math, since a ‘\’ ordinarily produces a literal (typewriter) ‘\’. You can also use @backslashchar{} in any mode to get a typewriter backslash. See section Inserting ‘\’ with @backslashchar{}.

For displayed equations, you must at present use TeX directly (see section Raw Formatter Commands).


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12.8 Glyphs for Text

Texinfo has support for a few additional glyphs that are commonly used in printed text but not available in ASCII. Of course, there are many thousands more. It is possible to use Unicode characters as-is as far as makeinfo is concerned, but TeX is not so lucky.


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12.8.1 @TeX{} (TeX) and @LaTeX{} (LaTeX)

Use the @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 ‘TeX’.

Similarly, use the @LaTeX{} command to generate ‘LaTeX’, which is even more special in printed manuals (and different from the incorrect La@TeX{}. In Info, the result is just ‘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 for Texinfo, in that they use both uppercase and lowercase letters.


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12.8.2 @copyright{} (©)

Use the @copyright{} command to generate the copyright symbol, ‘©’. Where possible, this is a ‘c’ inside a circle; in Info, this is ‘(C)’.

Legally, it’s not necessary to use the copyright symbol; the English word ‘Copyright’ suffices, according to international treaty.


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12.8.3 @registeredsymbol{} (®)

Use the @registeredsymbol{} command to generate the registered symbol, ‘®’. Where possible, this is an ‘R’ inside a circle; in Info, this is ‘(R)’.


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12.8.4 @dots (…) and @enddots (...)

An ellipsis (a sequence of dots) would be spaced wrong when typeset as a string of periods, so a special command is used in Texinfo: use the @dots{} command to generate a normal ellipsis, which is three dots in a row, appropriately spaced … like so. To emphasize: 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.

The @enddots{} command generates an end-of-sentence ellipsis, which also has three dots, but with different spacing afterwards, ... Look closely to see the difference.

Here is an ellipsis: … Here are three periods in a row: ...

In printed (and usually HTML) output, the three periods in a row are much closer together than the dots in the ellipsis.


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12.8.5 @bullet (•)

Use the @bullet{} command to generate a large round dot, or the closest possible thing to one. In Info, an asterisk is used. Here is a bullet: •

When you use @bullet in @itemize, you do not need to type the braces, because @itemize supplies them. (see section @itemize: Making an Itemized List).


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12.8.6 @euro (€): Euro Currency Symbol

Use the @euro{} command to generate ‘€’. Where possible, this is the symbol for the Euro currency. Otherwise, the word ‘Euro’ is used.

Texinfo cannot magically synthesize support for the Euro symbol where the underlying system (fonts, software, whatever) does not support it. Therefore, you may find it preferable to use the word “Euro”. (In banking contexts, the abbreviation for the Euro is EUR.)

In order to get the Euro symbol in encoded Info output, for example, it is necessary to specify @documentencoding ISO-8859-15 or @documentencoding UTF-8 (See section @documentencoding enc: Set Input Encoding.) The Euro symbol is in ISO 8859-15 (aka Latin 9), and is not in the more widely-used ISO 8859-1 (Latin 1).

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 feymr10 (along with other variables). It is freely available, of course; you can download it from http://ctan.org/pkg/eurosym, among other places. The distribution includes installation instructions.


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12.8.7 @pounds (£): Pounds Sterling

Use the @pounds{} command to generate ‘£’. Where possible, this is the symbol for the pounds sterling British currency. Otherwise, it is ‘#’.


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12.8.8 @textdegree (°): Degrees Symbol

Use the @textdegree{} command to generate ‘°’. Where possible, this is the normal symbol for degrees. Otherwise, it is an ‘o’.


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12.8.9 @minus (-): Inserting a Minus Sign

Use the @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:

-’ is a minus sign generated with ‘@minus{}’,

‘-’ is a hyphen generated with the character ‘-’,

‘—’ is an em-dash for text.

In the fixed-width font used by Info, @minus{} is the same as a hyphen.

You should not use @minus{} inside @code or @example because the width distinction is not made in the fixed-width font they use.

When you use @minus to specify the mark beginning each entry in an itemized list, you do not need to type the braces (see section @itemize: Making an Itemized List).

If you actually want to typeset some math that does a subtraction, it is better to use @math. Then the regular ‘-’ character produces a minus sign, as in @math{a-b} (see section @math: Inserting Mathematical Expressions).


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12.8.10 @geq (≥) and @leq (≤): Inserting Relations

Use the @geq{} and @leq{} commands to generate greater-than-or-equal and less-than-equal-signs, ‘≥’ and ‘≤’. When those symbols are not available, the ASCII sequences ‘>=’ and ‘<=’ are output.


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12.9 Glyphs for Programming

In Texinfo, code is often illustrated in examples that are delimited by @example and @end example, or by @lisp and @end lisp. In such examples, you can indicate the results of evaluation or an expansion using ‘’ or ‘’. Likewise, there are commands to insert glyphs to indicate printed output, error messages, equivalence of expressions, the location of point in an editor, and GUI operation sequences.

The glyph-insertion commands do not need to be used within an example, but most often they are. All glyph-insertion commands are followed by empty braces.


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12.9.1 Glyphs Summary

Here is a summary of the glyph commands:

@result{} indicates the result of an expression.

@expansion{} indicates the results of a macro expansion.

-|

@print{} indicates printed output.

error-->

@error{} indicates the following text is an error message.

@equiv{} indicates the exact equivalence of two forms.

@point{} shows the location of point.

A → B

@clicksequence{A @click{} B indicates a GUI operation sequence: first A, then clicking B, or choosing B from a menu, or otherwise selecting it.


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12.9.2 @result{} (⇒): Result of an Expression

Use the @result{} command to indicate the result of evaluating an expression.

The @result{} command is displayed as ‘’, either a double stemmed arrow or (when that is not available) the ASCII sequence ‘=>’.

Thus, the following,

(cdr '(1 2 3))
    ⇒ (2 3)

may be read as “(cdr '(1 2 3)) evaluates to (2 3)”.


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12.9.3 @expansion{} (→): Indicating an Expansion

When an expression is a macro call, it expands into a new expression. You can indicate the result of the expansion with the @expansion{} command.

The @expansion{} command is displayed as ‘’, either a long arrow with a flat base or (when that is not available) the ASCII sequence ‘==>’.

For example, the following

@lisp
(third '(a b c))
    @expansion{} (car (cdr (cdr '(a b c))))
    @result{} c
@end lisp

produces

(third '(a b c))
    → (car (cdr (cdr '(a b c))))
    ⇒ c

which may be read as:

(third '(a b c)) expands to (car (cdr (cdr '(a b c)))); the result of evaluating the expression is c.

Often, as in this case, an example looks better if the @expansion{} and @result{} commands are indented.


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12.9.4 @print{} (-|): Indicating Generated Output

Sometimes an expression will generate output during its execution. You can indicate such displayed output with the @print{} command.

The @print{} command is displayed as ‘-|’, either a horizontal dash butting against a vertical bar or (when that is not available) the ASCII sequence ‘-|’.

In the following example, the printed text is indicated with ‘-|’, and the value of the expression follows on the last line.

(progn (print 'foo) (print 'bar))
    -| foo
    -| bar
    ⇒ bar

In a Texinfo source file, this example is written as follows:

@lisp
(progn (print 'foo) (print 'bar))
    @print{} foo
    @print{} bar
    @result{} bar
@end lisp

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12.9.5 @error{} (error-->): Indicating an Error Message

A piece of code may cause an error when you evaluate it. You can designate the error message with the @error{} command.

The @error{} command is displayed as ‘error-->’, either the word ‘error’ in a box in the printed output, the word error followed by an arrow in other formats or (when no arrow is available) ‘error-->’.

Thus,

@lisp
(+ 23 'x)
@error{} Wrong type argument: integer-or-marker-p, x
@end lisp

produces

(+ 23 'x)
error--> Wrong type argument: integer-or-marker-p, x

This indicates that the following error message is printed when you evaluate the expression:

Wrong type argument: integer-or-marker-p, x

The word ‘error-->’ itself is not part of the error message.


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12.9.6 @equiv{} (≡): Indicating Equivalence

Sometimes two expressions produce identical results. You can indicate the exact equivalence of two forms with the @equiv{} command. The @equiv{} command is displayed as ‘’, either a standard mathematical equivalence sign (three parallel horizontal lines) or (when that is not available) as the ASCII sequence ‘==’.

Thus,

@lisp
(make-sparse-keymap) @equiv{} (list 'keymap)
@end lisp

produces

(make-sparse-keymap) ≡ (list 'keymap)

This indicates that evaluating (make-sparse-keymap) produces identical results to evaluating (list 'keymap).


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12.9.7 @point{} (∗): Indicating Point in a Buffer

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.

You can use the ‘@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 between two characters where point is located.)

The @point{} command is displayed as ‘’, either a pointed star or (when that is not available) the ASCII sequence ‘-!-’.

The following example shows the contents of buffer ‘foo’ before and after evaluating a Lisp command to insert the word changed.

---------- Buffer: foo ----------
This is the ∗contents of foo.
---------- Buffer: foo ----------

(insert "changed ")
    ⇒ nil
---------- Buffer: foo ----------
This is the changed ∗contents of foo.
---------- Buffer: foo ----------

In a Texinfo source file, the example is written like this:

@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

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12.9.8 Click Sequences

When documenting graphical interfaces, it is necessary to describe sequences such as ‘Click on ‘File’, then choose ‘Open’, then …’. Texinfo offers commands @clicksequence and click to represent this, typically used like this:

… @clicksequence{File @click{} Open} …

which produces:

… File → Open …

The @click command produces a right arrow by default; this glyph is also available independently via the command @arrow{}.

You can change the glyph produced by @click with the command @clickstyle, which takes a command name as its single argument on the rest of the line, much like @itemize and friends (see section @itemize: Making an Itemized List). The command should produce a glyph, and the usual empty braces ‘{}’ are omitted. Here’s an example:

@clickstyle @result
… @clicksequence{File @click{} Open} …

now produces:

… File ⇒ Open …

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12.10 Inserting Unicode: @U

The command @U{hex} inserts a representation of the Unicode character U+hex. For example, @U{0132} inserts the Dutch ‘IJ’ ligature (poorly shown here as simply the two letters ‘I’ and ‘J’).

The hex value should be at least four hex digits; leading zeros are not added. In general, hex must specify a valid normal Unicode character; e.g., U+10FFFF (the very last code point) is invalid by definition, and thus cannot be inserted this way.

@U is useful for inserting occasional glyphs for which Texinfo has no dedicated command, while allowing the Texinfo source to remain purely 7-bit ASCII for maximum portability.

This command has many limitations—the same limitations as inserting Unicode characters in UTF-8 or another binary form. First and most importantly, TeX knows nothing about most of Unicode. Supporting specific additional glyphs upon request is possible, but it’s not viable for ‘texinfo.tex’ to support whole additional scripts (Japanese, Urdu, …). The @U command does nothing to change this. If the specified character is not supported in TeX, an error is given. (See section @documentencoding enc: Set Input Encoding.)

In HTML, XML, and Docbook, the output from @U is always an entity reference of the form ‘&#xhex;’, as in ‘&#x0132;’ for the example above. This should work even when an HTML document uses some other encoding (say, Latin 1) and the given character is not supported in that encoding.

In Info and plain text, if the document encoding is specified explicitly to be UTF-8, the output will be the UTF-8 representation of the character U+hex (presuming it’s a valid character). In all other cases, the output is the ASCII sequence ‘U+hex’, as in the six ASCII characters ‘U+0132’ for the example above.

That’s all. No magic!


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13 Forcing and Preventing Breaks

Line and page breaks can sometimes occur in the ‘wrong’ place in one or another form of output. It’s up to you to ensure that text looks right in all the output formats.

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.

You can use the break, break prevention, or pagination commands to fix problematic line and page breaks.


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13.1 Break Commands

The break commands create or allow line and paragraph breaks:

@*

Force a line break.

@sp n

Skip n blank lines.

@-

Insert a discretionary hyphen.

@hyphenation{hy-phen-a-ted words}

Define hyphen points in hy-phen-a-ted words.

These commands hold text together on a single line:

@w{text}

Prevent text from being split and hyphenated across two lines.

@tie{}

Insert a normal interword space at which a line break may not occur.

The pagination commands apply only to printed output, since other output formats do not have pages.

@page

Start a new page.

@group

Hold text together that must appear on one page.

@need mils

Start a new page if not enough space on this one.


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13.2 @* and @/: Generate and Allow Line Breaks

The @* command forces a line break in all output formats. The @/ command allows a line break (printed manual only).

Here is an example with @*:

This sentence is broken @*into two lines.

produces

This sentence is broken
into two lines.

The @/ command can be useful within long urls or other identifiers where TeX can’t find a good place to break. TeX will automatically break urls at the natural places (see section URL Line Breaking), so only use @/ if you need it. @/ has no effect in the other output format.


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13.3 @- and @hyphenation: Helping TeX Hyphenate

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:

@-

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 (see section Overfull “hboxes”). TeX will not insert any hyphenation points itself into a word containing @-.

@hyphenation{hy-phen-a-ted words}

Tell TeX how to hyphenate hy-phen-a-ted words. As shown, you put a ‘-’ at each hyphenation point. For example:

@hyphenation{man-u-script man-u-scripts}

TeX only uses the specified hyphenation points when the words match exactly, so give all necessary variants, such as plurals.

Info, HTML, and other non-TeX output is not hyphenated, so none of these commands have any effect there.


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13.4 @allowcodebreaks: Control Line Breaks in @code

Ordinarily, TeX considers breaking lines at ‘-’ and ‘_’ characters within @code and related commands (see section @code{sample-code}), more or less as if they were “empty” hyphenation points.

This is necessary since many manuals, especially for Lisp-family languages, must document very long identifiers. On the other hand, some manuals don’t have this problems, and you may not wish to allow a line break at the underscore in, for example, SIZE_MAX, or even worse, after any of the four underscores in __typeof__.

So Texinfo provides this command:

@allowcodebreaks false

to prevent from breaking at ‘-’ or ‘_’ within @code. You can go back to allowing such breaks with @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 except in HTML and TeX output.


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13.5 @w{text}: Prevent Line Breaks

@w{text} outputs text, while prohibiting line breaks within text.

Thus, you can use @w to produce a non-breakable space, fixed at the width of a normal interword space:

@w{ } @w{ } @w{ } indentation.

produces:

      indentation.

The space from @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); for that, see the @tie command in the next section.

You can also use the @w command to prevent TeX from automatically hyphenating a long name or phrase that happens to fall near the end of a line. makeinfo does not ever hyphenate words.

You can also use @w to avoid unwanted keyword expansion in source control systems. For example, to literally write $Id$ in your document, use @w{$}Id$. This trick isn’t effective in Info or plain text output, though.


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13.6 @tie{}: Inserting an Unbreakable Space

The @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:

@TeX{} was written by Donald E.@tie{}Knuth.

produces:

TeX was written by Donald E. Knuth.

There are two important differences between @tie{} and @w{ }:


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13.7 @sp n: Insert Blank Lines

A line beginning with and containing only @sp n generates n blank lines of space in both the printed manual and the Info file. @sp also forces a paragraph break. For example,

@sp 2

generates two blank lines.

The @sp command is most often used in the title page.


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13.8 @page: Start a New Page

A line containing only @page starts a new page in a printed manual. In other formats, without the concept of pages, it starts a new paragraph. A @page command is often used in the @titlepage section of a Texinfo file to start the copyright page.


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13.9 @group: Prevent Page Breaks

The @group command (on a line by itself) is used inside an @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 @end group. These two lines produce no output of their own, and in the Info file output they have no effect at all.

Although @group would make sense conceptually in a wide variety of contexts, its current implementation works reliably only within @example and variants, and within @display, @format, @flushleft and @flushright. See section Quotations and Examples. (What all these commands have in common is that each line of input produces a line of output.) In other contexts, @group can cause anomalous vertical spacing.

This formatting requirement means that you should write:

@example
@group
…
@end group
@end example

with the @group and @end group commands inside the @example and @end example commands.

The @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 @group and @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 @end group if you get incomprehensible error messages in TeX.


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13.10 @need mils: Prevent Page Breaks

A line containing only @need n starts a new page in a printed manual if fewer than n mils (thousandths of an inch) remain on the current page. Do not use braces around the argument n. The @need command has no effect on other output formats since they are not paginated.

This paragraph is preceded by a @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:

@need 800
This paragraph is preceded by …

The @need command is useful for preventing orphans: single lines at the bottoms of printed pages.


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14 Definition Commands

The @deffn command and the other definition commands enable you to describe functions, variables, macros, commands, user options, special forms and other such artifacts in a uniform format.

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: @deffn enters the name into the index of functions, @defvr enters it into the index of variables, and so on (see section 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 @table rather than the definition commands.


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14.1 The Template for a Definition

The @deffn command is used for definitions of entities that resemble functions. To write a definition using the @deffn command, write the @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 @end deffn command written on a line of its own.

The other definition commands follow the same format: a line with the @def… command and whatever arguments are appropriate for that command; the body of the definition; and a corresponding @end line.

The template for a definition looks like this:

@deffn category name argumentsbody-of-definition
@end deffn

For example,

@deffn Command forward-word count
This command moves point forward @var{count} words
(or backward if @var{count} is negative). …
@end deffn

produces

Command: forward-word count

This command moves point forward count words (or backward if count is negative). …

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:

@deffn {Interactive Command} isearch-forward
…
@end deffn

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 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, ‘{declaraci@'on}’ if you are writing in Spanish.

Some of the definition commands are more general than others. The @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 (@defun, @defmac, and @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 @defvr command is accompanied by several specialized variations for describing particular kinds of variables.

See section A Sample Function Definition, for a detailed example of a function definition, including the use of @example inside the definition.


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14.2 Definition Command Continuation Lines

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 ‘@’ at the end of each line to be continued. Here’s an example:

@defun fn-name @
  arg1 arg2 arg3
This is the basic continued defun.
@end defun

produces:

Function: fn-name arg1 arg2 arg3

This is the basic continued defun.

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, in the same way; put an @ at the end of each line to be continued.

In general, any number of spaces or tabs before the @ continuation character 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:

@deffn {Category @
  Name} …

The output (not shown) has excess space between ‘Category’ and ‘Name’. To avoid this, elide the unwanted whitespace in your input, or put the continuation @ outside braces.

@ does not function as a continuation character in any other context. Ordinarily, ‘@’ followed by a whitespace character (space, tab, newline) produces a normal interword space (see section Multiple Spaces).


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14.3 Optional and Repeated Arguments

Some entities take optional or repeated arguments, conventionally specified by using square brackets and ellipses: an argument enclosed within square brackets is optional, and an argument followed by an ellipsis is optional and may be repeated more than once.

Thus, [optional-arg] means that optional-arg is optional and repeated-args 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 @defspec line of an example of an imaginary (complicated) special form:

Special Form: foobar (var [from to [inc]]) body…

In this example, the arguments from and to are optional, but must both be present or both absent. If they are present, inc may optionally be specified as well. These arguments are grouped with the argument var into a list, to distinguish them from body, which includes all remaining elements of the form.

In a Texinfo source file, this @defspec line is written like this:

@defspec foobar (var [from to [inc]]) body@dots{}

The function is listed in the Command and Variable Index under ‘foobar’.


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14.4 @deffnx, et al.: Two or More ‘First’ Lines

To create two or more ‘first’ or header lines for a definition, follow the first @deffn line by a line beginning with @deffnx. The @deffnx command works exactly like @deffn except that it does not generate extra vertical white space between it and the preceding line.

For example,

@deffn {Interactive Command} isearch-forward
@deffnx {Interactive Command} isearch-backward
These two search commands are similar except …
@end deffn

produces

Interactive Command: isearch-forward
Interactive Command: isearch-backward

These two search commands are similar except …

Each definition command has an ‘x’ form: @defunx, @defvrx, @deftypefunx, etc.

The ‘x’ forms work similarly to @itemx (see section @itemx: Second and Subsequent Items).


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14.5 The Definition Commands

Texinfo provides more than a dozen definition commands, all of which are described in this section.

The definition commands automatically enter the name of the entity in the appropriate index: for example, @deffn, @defun, and @defmac enter function names in the index of functions; @defvr and @defvar enter variable names in the index of variables.

Although the examples that follow mostly illustrate Lisp, the commands can be used for other programming languages.


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14.5.1 Functions and Similar Entities

This section describes the commands for describing functions and similar entities:

@deffn category name arguments

The @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 @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 @end deffn on a line of its own.

For example, here is a definition:

@deffn Command forward-char nchars
Move point forward @var{nchars} characters.
@end deffn

This shows a rather terse definition for a “command” named forward-char with one argument, nchars.

@deffn prints argument names such as 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 @var to refer to the value of the argument. In the example above, we used ‘@var{nchars}’ in this way.

In the extremely unusual case when an argument name contains ‘--’, or another character sequence which is treated specially (see section General Syntactic Conventions), use @code around the special characters. This avoids the conversion to typographic en-dashes and em-dashes.

The template for @deffn is:

@deffn category name argumentsbody-of-definition
@end deffn
@defun name arguments

The @defun command is the definition command for functions. @defun is equivalent to ‘@deffn Function …’. Terminate the definition with @end defun on a line of its own. Thus, the template is:

@defun function-name argumentsbody-of-definition
@end defun
@defmac name arguments

The @defmac command is the definition command for macros. @defmac is equivalent to ‘@deffn Macro …’ and works like @defun.

@defspec name arguments

The @defspec command is the definition command for special forms. (In Lisp, a special form is an entity much like a function; see Special Forms in GNU Emacs Lisp Reference Manual.) @defspec is equivalent to ‘@deffn {Special Form} …’ and works like @defun.

All these commands create entries in the index of functions.


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14.5.2 Variables and Similar Entities

Here are the commands for defining variables and similar entities:

@defvr category name

The @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 @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.

We recommend capitalizing 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,

@defvr {User Option} fill-column
This buffer-local variable specifies
the maximum width of filled lines.
…
@end defvr

Terminate the definition with @end defvr on a line of its own.

The template is:

@defvr category name
body-of-definition
@end defvr

@defvr creates an entry in the index of variables for name.

@defvar name

The @defvar command is the definition command for variables. @defvar is equivalent to ‘@defvr Variable …’.

For example:

@defvar kill-ring
…
@end defvar

The template is:

@defvar name
body-of-definition
@end defvar

@defvar creates an entry in the index of variables for name.

@defopt name

The @defopt command is the definition command for user options, i.e., variables intended for users to change according to taste; Emacs has many such (see Variables in The GNU Emacs Manual). @defopt is equivalent to ‘@defvr {User Option} …’ and works like @defvar. It creates an entry in the index of variables.


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14.5.3 Functions in Typed Languages

The @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++.

@deftypefn category data-type name arguments

The @deftypefn command is the general definition command for functions and similar entities that may take arguments and that are typed. The @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.

For example,

@deftypefn {Library Function} int foobar @
  (int @var{foo}, float @var{bar})
…
@end deftypefn

produces:

Library Function: int foobar (int foo, float bar)

This means that foobar is a “library function” that returns an int, and its arguments are foo (an int) and bar (a float).

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) write everything as straight text, and it will be printed in slanted type; (b) use @var for the variable names, which will uppercase the variable names in Info and use the slanted typewriter font in printed output; (c) use @var for the variable names and @code for the type names and keywords, which will be dutifully obeyed.

The template for @deftypefn is:

@deftypefn category data-type name argumentsbody-of-description
@end deftypefn

Note that if the category or data type is more than one word then it must be enclosed in braces to make it a single argument.

If you are describing a procedure in a language that has packages, such as Ada, you might consider using @deftypefn in a manner somewhat contrary to the convention described in the preceding paragraphs. For example:

@deftypefn stacks private push @
       (@var{s}:in out stack; @
       @var{n}:in integer)
…
@end deftypefn

(In these examples the @deftypefn arguments are shown using continuations (see section Definition Command Continuation Lines), but could be on a single line.)

In this instance, the procedure is classified as belonging to the package stacks rather than classified as a ‘procedure’ and its data type is described as private. (The name of the procedure is push, and its arguments are s and n.)

@deftypefn creates an entry in the index of functions for name.

@deftypefun data-type name arguments

The @deftypefun command is the specialized definition command for functions in typed languages. The command is equivalent to ‘@deftypefn Function …’. The template is:

@deftypefun type name argumentsbody-of-description
@end deftypefun

@deftypefun creates an entry in the index of functions for name.

Ordinarily, the return type is printed on the same line as the function name and arguments, as shown above. In source code, GNU style is to put the return type on a line by itself. So Texinfo provides an option to do that: @deftypefnnewline on.

This affects typed functions only—not untyped functions, not typed variables, etc.. Specifically, it affects the commands in this section, and the analogous commands for object-oriented languages, namely @deftypeop and @deftypemethod (see section Object-Oriented Methods).

Specifying @deftypefnnewline off reverts to the default.


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14.5.4 Variables in Typed Languages

Variables in typed languages are handled in a manner similar to functions in typed languages. See section Functions in Typed Languages. The general definition command @deftypevr corresponds to @deftypefn and the specialized definition command @deftypevar corresponds to @deftypefun.

@deftypevr category data-type name

The @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.

The @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.

For example:

@deftypevr {Global Flag} int enable
…
@end deftypevr

produces the following:

Global Flag: int enable

The template is:

@deftypevr category data-type name
body-of-description
@end deftypevr
@deftypevar data-type name

The @deftypevar command is the specialized definition command for variables in typed languages. @deftypevar is equivalent to ‘@deftypevr Variable …’. The template is:

@deftypevar data-type name
body-of-description
@end deftypevar

These commands create entries in the index of variables.


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14.5.5 Data Types

Here is the command for data types:

@deftp category name attributes

The @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 int or float), and then by names of attributes of objects of that type. Thus, you could use this command for describing int or float, in which case you could use 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.)

In Lisp, for example, pair names a particular data type, and an object of that type has two slots called the CAR and the CDR. Here is how you would write the first line of a definition of pair.

@deftp {Data type} pair car cdr
…
@end deftp

The template is:

@deftp category name-of-type attributesbody-of-definition
@end deftp

@deftp creates an entry in the index of data types.


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14.5.6 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.


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14.5.6.1 Object-Oriented Variables

These commands allow you to define different sorts of variables in object-oriented programming languages.

@defcv category class name

The @defcv command is the general definition command for variables associated with classes in object-oriented programming. The @defcv command is followed by three arguments: the category of thing being defined, the class to which it belongs, and its name. For instance:

@defcv {Class Option} Window border-pattern
…
@end defcv

produces:

Class Option of Window: border-pattern

@defcv creates an entry in the index of variables.

@deftypecv category class data-type name

The @deftypecv command is the definition command for typed class variables in object-oriented programming. It is analogous to @defcv with the addition of the 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. For instance:

@deftypecv {Class Option} Window @code{int} border-pattern
…
@end deftypecv

produces:

Class Option of Window: int border-pattern

@deftypecv creates an entry in the index of variables.

@defivar class name

The @defivar command is the definition command for instance variables in object-oriented programming. @defivar is equivalent to ‘@defcv {Instance Variable} …’. For instance:

@defivar Window border-pattern
…
@end defivar

produces:

Instance Variable of Window: border-pattern

@defivar creates an entry in the index of variables.

@deftypeivar class data-type name

The @deftypeivar command is the definition command for typed instance variables in object-oriented programming. It is analogous to @defivar with the addition of the 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. For instance:

@deftypeivar Window @code{int} border-pattern
…
@end deftypeivar

produces:

Instance Variable of Window: int border-pattern

@deftypeivar creates an entry in the index of variables.


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14.5.6.2 Object-Oriented Methods

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.

@defop category class name arguments

The @defop command is the general definition command for these method-like entities.

For example, some systems have constructs called wrappers that are associated with classes as methods are, but that act more like macros than like functions. You could use @defop Wrapper to describe one of these.

Sometimes it is useful to distinguish methods and 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 expose; we would say that this window system defines an 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.

Often it makes more sense to document operations than methods. For example, window application developers need to know about the 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:

@defop Operation windows expose

The @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.

The template is:

@defop category class name argumentsbody-of-definition
@end defop

@defop creates an entry, such as ‘expose on windows’, in the index of functions.

@deftypeop category class data-type name arguments

The @deftypeop command is the definition command for typed operations in object-oriented programming. It is similar to @defop with the addition of the data-type parameter to specify the return type of the method. @deftypeop creates an entry in the index of functions.

@defmethod class name arguments

The @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.

@defmethod is equivalent to ‘@defop Method …’. 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.

For example:

@defmethod bar-class bar-method argument
…
@end defmethod

illustrates the definition for a method called bar-method of the class bar-class. The method takes an argument.

@defmethod creates an entry in the index of functions.

@deftypemethod class data-type name arguments

The @deftypemethod command is the definition command for methods in object-oriented typed languages, such as C++ and Java. It is similar to the @defmethod command with the addition of the data-type parameter to specify the return type of the method. @deftypemethod creates an entry in the index of functions.

The typed commands are affected by the @deftypefnnewline option (see section Functions in Typed Languages).


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14.6 Conventions for Writing Definitions

When you write a definition using @deffn, @defun, or one of the other definition commands, please take care to use arguments that indicate the meaning, as with the count argument to the forward-word function. Also, if the name of an argument contains the name of a type, such as integer, take care that the argument actually is of that type.


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14.7 A Sample Function Definition

A function definition uses the @defun and @end defun commands. The name of the function follows immediately after the @defun command and it is followed, on the same line, by the parameter list.

Here is a definition from Calling Functions in The GNU Emacs Lisp Reference Manual.

Function: apply function &rest arguments

apply calls function with arguments, just like funcall but with one difference: the last of arguments is a list of arguments to give to function, rather than a single argument. We also say that this list is appended to the other arguments.

apply returns the result of calling function. As with funcall, function must either be a Lisp function or a primitive function; special forms and macros do not make sense in apply.

(setq f 'list)
    ⇒ list
(apply f 'x 'y 'z)
error--> Wrong type argument: listp, z
(apply '+ 1 2 '(3 4))
    ⇒ 10
(apply '+ '(1 2 3 4))
    ⇒ 10

(apply 'append '((a b c) nil (x y z) nil))
    ⇒ (a b c x y z)

An interesting example of using apply is found in the description of mapcar.

In the Texinfo source file, this example looks like this:

@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}.
@end defun

In this manual, this function is listed in the Command and Variable Index under apply.

Ordinary variables and user options are described using a format like that for functions except that variables do not take arguments.


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15 Internationalization

Texinfo has some support for writing in languages other than English, although this area still needs considerable work. (If you are the one helping to translate the fixed strings written to documents, see section Internationalization of Document Strings.)

For a list of the various accented and special characters Texinfo supports, see Inserting Accents.


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15.1 @documentlanguage ll[_cc]: Set the Document Language

The @documentlanguage command declares the current document locale. Write it on a line by itself, near the beginning of the file.

@documentlanguage ll[_cc]

Include a two-letter ISO 639-2 language code (ll) following the command name, optionally followed by an underscore and two-letter ISO 3166 two-letter country code (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 en_US for US English.

As with GNU Gettext (see Top in Gettext), if the country code is omitted, the main dialect is assumed where possible. For example, de is equivalent to de_DE (German as spoken in Germany).

For Info and other online output, this command changes the translation of various document strings such as “see” in cross-references (see section Cross-references), “Function” in defuns (see section 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.

For TeX, this command causes a file ‘txi-locale.tex’ to be read (if it exists). If @documentlanguage argument contains the optional ‘_cc’ suffix, this is tried first. For example, with @documentlanguage de_DE, TeX first looks for ‘txi-de_DE.tex’, then ‘txi-de.tex’.

Such a ‘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.

@documentlanguage also changes TeX’s current hyphenation patterns, if the TeX program being run has the necessary support included. This will generally not be the case for tex itself, but will usually be the case for up-to-date distributions of the extended TeX programs etex (DVI output) and pdftex (PDF output). texi2dvi will use the extended TeXs if they are available (see section Format with texi2dvi).

In September 2006, the W3C Internationalization Activity released a new recommendation for specifying languages: http://www.rfc-editor.org/rfc/bcp/bcp47.txt. When Gettext supports this new scheme, Texinfo will too.

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 639, http://www.loc.gov/standards/iso639-2/. The country codes and the official web site for ISO 3166 can be found via http://en.wikipedia.org/wiki/ISO_3166.


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15.2 @documentencoding enc: Set Input Encoding

The @documentencoding command declares the input document encoding, and can also affect the encoding of the output. Write it on a line by itself, with a valid encoding specification following, near the beginning of the file.

@documentencoding enc

Texinfo supports these encodings:

US-ASCII

This has no particular effect, but it’s included for completeness.

UTF-8

The vast global character encoding, expressed in 8-bit bytes.

ISO-8859-1
ISO-8859-15
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 (€).

A full description of the encodings is beyond our scope here; one useful reference is http://czyborra.com/charsets/iso8859.html.

koi8-r

This is the commonly used encoding for the Russian language.

koi8-u

This is the commonly used encoding for the Ukrainian language.

Specifying an encoding enc has the following effects:

In Info output, a so-called ‘Local Variables’ section (see File Variables in The GNU Emacs Manual) is output including enc. This allows Info readers to set the encoding appropriately. It looks like this:

Local Variables:
coding: enc
End:

Also, in Info and plain text output, unless the option ‘--disable-encoding’ is given to makeinfo, accent constructs and special characters, such as @'e, are output as the actual 8-bit or UTF-8 character in the given encoding where possible.

In HTML output, a ‘<meta>’ tag is output, in the ‘<head>’ section of the HTML, that specifies 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. That looks like this:

<meta http-equiv="Content-Type" content="text/html;
     charset=enc">

In XML and Docbook output, UTF-8 is always used for the output, according to the conventions of 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.

Although modern TeX systems support nearly every script in use in the world, this wide-ranging support is not available in ‘texinfo.tex’, and it’s not feasible to duplicate or incorporate all that effort. (Our plan to support other scripts is to create a LaTeX back-end to texi2any, where the support is already present.)

For maximum portability of Texinfo documents across the many different user environments in the world, we recommend sticking to 7-bit ASCII in the input unless your particular manual needs a substantial amount of non-ASCII, e.g., it’s written in German. You can use the @U command to insert an occasional needed character (see section Inserting Unicode: @U).


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16 Conditionally Visible Text

The 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.


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16.1 Conditional Commands

Texinfo has an @ifformat environment for each output format, to allow conditional inclusion of text for a particular output format.

@ifinfo begins segments of text that should be ignored by TeX when it typesets the printed manual, and by makeinfo when not producing Info output. The segment of text appears only in the Info file and, for historical compatibility, the plain text output.

The environments for the other formats are analogous:

@ifdocbook … @end ifdocbook

Text to appear only in the Docbook output.

@ifhtml … @end ifhtml

Text to appear only in the HTML output.

@ifplaintext … @end ifplaintext

Text to appear only in the plain text output.

@iftex … @end iftex

Text to appear only in the printed manual.

@ifxml … @end ifxml

Text to appear only in the XML output.

The @if… and @end if… commands must appear on lines by themselves in your source file. The newlines following the commands are (more or less) treated as whitespace, so that the conditional text is flowed normally into a surrounding paragraph.

The @if… constructs are intended to conditionalize normal Texinfo source; see section Raw Formatter Commands, for using underlying format commands directly.

Here is an example showing all these conditionals:

@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

The preceding example produces the following line:

And this text will only appear in HTML.

Notice that you only see one of the input lines, depending on which version of the manual you are reading.

In complex documents, you may want Texinfo to issue an error message in some conditionals that should not ever be processed. The @errormsg{text} command will do this; it takes one argument, the text of the error message.

We mention @errormsg{} here even though it is not strictly related to conditionals, since in practice it is most likely to be useful in that context. Technically, it can be used anywhere. See section External Macro Processors: Line Directives, for a caveat regarding the line numbers which @errormsg emits in TeX.


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16.2 Conditional Not Commands

You can specify text to be included in any output format other than a given one with the @ifnot… environments:

@ifnotdocbook … @end ifnotdocbook
@ifnothtml … @end ifnothtml
@ifnotinfo … @end ifnotinfo
@ifnotplaintext … @end ifnotplaintext
@ifnottex … @end ifnottex
@ifnotxml … @end ifnotxml

The @ifnot… command and the @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 ignored. Otherwise, it is included.

There is one exception (for historical compatibility): @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 @ifnotplaintext, like this:

@ifinfo
@ifnotplaintext
This will be in Info, but not plain text.
@end ifnotplaintext
@end ifinfo

The regions delimited by these commands are ordinary Texinfo source as with @iftex, not raw formatter source as with @tex (see section Raw Formatter Commands).


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16.3 Raw Formatter Commands

The @if… conditionals just described must be used only with normal Texinfo source. For instance, most features of plain TeX will not work within @iftex. The purpose of @if… is to provide conditional processing for Texinfo source, not provide access to underlying formatting features. For that, Texinfo provides so-called raw formatter commands. They should only be used when truly required (most documents do not need them).

The first raw formatter command is @tex. You can enter plain TeX completely, and use ‘\’ in the TeX commands, by delineating a region with the @tex and @end tex commands. All plain TeX commands and category codes are restored within a @tex region. The sole exception is that the @ character still introduces a command, so that @end tex can be recognized. Texinfo processors will not output material in such a region, unless TeX output is being produced.

In complex cases, you may wish to define new TeX macros within @tex. You must use \gdef to do this, not \def, because @tex regions are processed in a TeX group. If you need to make several definitions, you may wish to set \globaldefs=1 (its value will be restored to zero as usual when the group ends at @end tex, so it won’t cause problems with the rest of the document).

As an example, here is a displayed equation written in plain TeX:

@tex
$$ \chi^2 = \sum_{i=1}^N
         \left (y_i - (a + b x_i)
         \over \sigma_i\right)^2 $$
@end tex

The output of this example will appear only in a printed manual. If you are reading this in a format not generated by TeX, you will not see the equation that appears in the printed manual.

Analogously, you can use @ifhtml … @end ifhtml to delimit Texinfo source to be included in HTML output only, and @html … @end html for a region of raw HTML.

Likewise, you can use @ifxml … @end ifxml to delimit Texinfo source to be included in XML output only, and @xml … @end xml for a region of raw XML. Regions of raw text in other formats will also be present in the XML output, but with protection of XML characters and within corresponding elements. For example, the raw HTML text:

@html
<br />
@end html

will be included in the XML output as:

<html>
&lt;br /&gt;
</html>

Again likewise, you can use @ifdocbook … @end ifdocbook to delimit Texinfo source to be included in Docbook output only, and @docbook … @end docbook for a region of raw Docbook.

The behavior of newlines in raw regions is unspecified.

In all cases, in raw processing, @ retains the same meaning as in the remainder of the document. Thus, the Texinfo processors must recognize and even execute, to some extent, the contents of the raw regions, regardless of the final output format. Therefore, specifying changes that globally affect the document inside a raw region leads to unpredictable and generally undesirable behavior. For example, using the @kbdinputstyle command inside a raw region is undefined.

The remedy is simple: don’t do that. Use the raw formatter commands for their intended purpose, of providing material directly in the underlying format. When you simply want to give different Texinfo specifications for different output formats, use the @if… conditionals and stay in Texinfo syntax.


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16.4 Inline Conditionals: @inline, @inlineifelse, @inlineraw

Texinfo provides a set of conditional commands with arguments given within braces:

@inlinefmt{format, text}

Process the Texinfo text if format output is being generated.

@inlinefmtifelse{format, then-text, else-text}

Process the Texinfo then-text if format output is being generated; otherwise, process else-text.

@inlineraw{format, text}

Similar, but for raw text (see section Raw Formatter Commands).

The supported format names are:

docbook  html  info  plaintext  tex  xml

For example,

@inlinefmt{html, @emph{HTML-only text}}

is nearly equivalent to

@ifhtml
@emph{HTML-only text}
@end ifhtml

except that no whitespace is added, as happens in the latter (environment) case.

In these commands, whitespace is ignored after the comma separating the arguments, as usual, but is not ignored at the end of text.

To insert a literal at sign, left brace, or right brace in one of the arguments, you must use the alphabetic commands @atchar{} (see section Inserting ‘@’ with @@ and @atchar{}), and @lbracechar{} or @rbracechar{} (see section Inserting ‘{ ‘}’ with @{ @} and @l rbracechar{}), or the parsing will become confused.

With @inlinefmtifelse, it is also necessary to use @comma{} to avoid mistaking a ‘,’ in the text for the delimiter. With @inlinefmt and @inlineraw, @comma{} is not required (though it’s fine to use it), since these commands always have exactly two arguments.

For TeX, the processed text cannot contain newline-delimited commands. Text to be ignored (i.e., for non-TeX) can, though.

Two other @inline... conditionals complement the @ifset and @ifclear commands; see the next section.


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16.5 Flags: @set, @clear, conditionals, and @value

You can direct the Texinfo formatting commands to format or ignore parts of a Texinfo file with the @set, @clear, @ifset, and @ifclear commands.

Here are brief descriptions of these commands, see the following sections for more details:

@set flag [value]

Set the variable flag, to the optional value if specified.

@clear flag

Undefine the variable flag, whether or not it was previously defined.

@ifset flag

If flag is set, text through the next @end ifset command is formatted. If flag is clear, text through the following @end ifset command is ignored.

@inlineifset{flag, text}

Brace-delimited version of @ifset.

@ifclear flag

If flag is set, text through the next @end ifclear command is ignored. If flag is clear, text through the following @end ifclear command is formatted.

@inlineifclear{flag, text}

Brace-delimited version of @ifclear.


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16.5.1 @set and @value

You use the @set command to specify a value for a flag, which is later expanded by the @value command.

A flag (aka variable) name is an identifier starting with an alphanumeric, ‘-’, or ‘_’. Subsequent characters, if any, may not be whitespace, ‘@’, braces, angle brackets, or any of ‘~`^+|’; other characters, such as ‘%’, may work. However, it is best to use only letters and numerals in a flag name, not ‘-’ or ‘_’ or others—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. However, unlike most other commands which take the rest of the line as a value, @set need not appear at the beginning of a line.

Write the @set command like this:

@set foo This is a string.

This sets the value of the flag foo to “This is a string.”.

The Texinfo formatters then replace a @value{flag} command with the string to which flag is set. Thus, when foo is set as shown above, the Texinfo formatters convert this:

@value{foo}
to this:
This is a string.

You can write a @value command within a paragraph; but you must write a @set command on a line of its own.

If you write the @set command like this:

@set foo

without specifying a string, the value of foo is the empty string.

If you clear a previously set flag with @clear flag, a subsequent @value{flag} command will report an error.

For example, if you set foo as follows:

@set howmuch very, very, very

then the formatters transform

It is a @value{howmuch} wet day.
into
It is a very, very, very wet day.

If you write

@clear howmuch

then the formatters transform

It is a @value{howmuch} wet day.
into
It is a {No value for "howmuch"} wet day.

@value cannot be reliably used as the argument to an accent command (see section Inserting Accents). For example, this fails:

@set myletter a
@'@value{myletter}    

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16.5.2 @ifset and @ifclear

When a flag is set, the Texinfo formatting commands format text between subsequent pairs of @ifset flag and @end ifset commands. When the flag is cleared, the Texinfo formatting commands do not format the text. @ifclear operates analogously.

Write the conditionally formatted text between @ifset flag and @end ifset commands, like this:

@ifset flag
conditional-text
@end ifset

For example, you can create one document that has two variants, such as a manual for a ‘large’ and ‘small’ model:

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 …

In the example, the formatting commands will format the text between @ifset large and @end ifset because the large flag is set.

When flag is cleared, the Texinfo formatting commands do not format the text between @ifset flag and @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 @clear large command after the @set large command (but before the conditional text), then the Texinfo formatting commands ignore the text between the @ifset large and @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 …”.

If a flag is cleared with a @clear flag command, then the formatting commands format text between subsequent pairs of @ifclear and @end ifclear commands. But if the flag is set with @set flag, then the formatting commands do not format text between an @ifclear and an @end ifclear command; rather, they ignore that text. An @ifclear command looks like this:

@ifclear flag

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16.5.3 @inlineifset and @inlineifclear

@inlineifset and @inlineifclear provide brace-delimited alternatives to the @ifset and @ifclear forms, similar to the other @inline... Commands (see section Inline Conditionals: @inline, @inlineifelse, @inlineraw). The same caveats about argument parsing given there apply here too.

@inlineifset{var, text}

Process the Texinfo text if the flag var is defined.

@inlineifclear{var, text}

Process the Texinfo text if the flag var is not defined.

Except for the syntax, their general behavior and purposes is the same as with @ifset and @ifclear, described in the previous section.


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16.5.4 @value Example

You can use the @value command to minimize the number of places you need to change when you record an update to a manual. See section GNU Sample Texts, for the full text of an example of using this to work with Automake distributions.

This example is adapted from Top in The GNU Make Manual.

  1. Set the flags:
    @set EDITION 0.35 Beta
    @set VERSION 3.63 Beta
    @set UPDATED 14 August 1992
    @set UPDATE-MONTH August 1992
    
  2. Write text for the @copying section (see section @copying: Declare Copying Permissions):
    @copying
    This is Edition @value{EDITION},
    last updated @value{UPDATED},
    of @cite{The GNU Make Manual},
    for @code{make}, version @value{VERSION}.
    
    Copyright …
    
    Permission is granted …
    @end copying
    
  3. Write text for the title page, for people reading the printed manual:
    @titlepage
    @title GNU Make
    @subtitle A Program for Directing Recompilation
    @subtitle Edition @value{EDITION}, …
    @subtitle @value{UPDATE-MONTH}
    @page
    @insertcopying
    …
    @end titlepage
    

    (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.)

  4. Write text for the Top node, for people reading the Info file:
    @ifnottex
    @node Top
    @top Make
    
    This is Edition @value{EDITION},
    last updated @value{UPDATED},
    of @cite{The GNU Make Manual},
    for @code{make}, version @value{VERSION}.
    @end ifnottex
    

    After you format the manual, the @value constructs have been expanded, so the output contains text like this:

    This is Edition 0.35 Beta, last updated 14 August 1992,
    of `The GNU Make Manual', for `make', Version 3.63 Beta.
    

When you update the manual, you change only the values of the flags; you do not need to edit the three sections.


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16.6 Testing for Texinfo Commands: @ifcommanddefined, @ifcommandnotdefined

Occasionally, you may want to arrange for your manual to test if a given Texinfo command is available and (presumably) do some sort of fallback formatting if not. There are conditionals @ifcommanddefined and @ifcommandnotdefined to do this. For example:

@ifcommanddefined node
Good, @samp{@@node} is defined.
@end ifcommanddefined

will output the expected ‘Good, ‘@node’ is defined.’.

This conditional will also consider any new commands defined by the document via @macro, @alias, @definfoenclose, and @def(code)index (see section Defining New Texinfo Commands) to be true. Caveat: the TeX implementation reports internal TeX commands, in addition to all the Texinfo commands, as being “defined”; the makeinfo implementation is reliable in this regard, however.

You can check the ‘NEWS’ file in the Texinfo source distribution and linked from the Texinfo home page (http://www.gnu.org/software/texinfo) to see when a particular command was added.

These command-checking conditionals themselves were added in Texinfo 5.0, released in 2013—decades after Texinfo’s inception. In order to test if they themselves are available, the predefined flag txicommandconditionals can be tested, like this:

@ifset txicommandconditionals
@ifcommandnotdefined foobarnode
(Good, @samp{@@foobarnode} is not defined.)
@end ifcommandnotdefined
@end ifset

Since flags (see the previous section) were added early in the existence of Texinfo, there is no problem with assuming they are available.

We recommend avoiding these tests whenever possible—which is usually the case. For many software packages, it is reasonable for all developers to have a given version of Texinfo (or newer) installed, and thus no reason to worry about older versions. (It is straightforward for anyone to download and install the Texinfo source; it does not have any problematic dependencies.)

The issue of Texinfo versions does not generally arise for end-users. With properly distributed packages, users need not process the Texinfo manual simply to build and install the package; they can use preformatted Info (or other) output files. This is desirable in general, to avoid unnecessary dependencies between packages (see Releases in GNU Coding Standards).


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16.7 Conditional Nesting

Conditionals can be nested; however, the details are a little tricky. The difficulty comes with failing conditionals, such as @ifhtml when HTML is not being produced, where the included text is to be ignored. However, it is not to be completely ignored, since it is useful to have one @ifset inside another, for example—that is a way to include text only if two conditions are met. Here’s an 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

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 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:

@ifset a
@ifset b
@ifclear ok  - ok, ignored
@end junky   - ok, ignored
@end ifset
@c WRONG - missing @end ifset.

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.


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17 Defining New Texinfo Commands

Texinfo provides several ways to define new commands (in all cases, it’s not recommended to try redefining existing commands):

Most generally of all (not just for defining new commands), it is possible to invoke any external macro processor and have Texinfo recognize so-called #line directives for error reporting.

If you want to do simple text substitution, @set and @value is the simplest approach (see section Flags: @set, @clear, conditionals, and @value).


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17.1 Defining Macros

You use the Texinfo @macro command to define a macro, like this:

@macro macroname{param1, param2, …}
text … \param1\ …
@end macro

The parameters param1, param2, … correspond to arguments supplied when the macro is subsequently used in the document (described in the next section).

For a macro to work consistently with TeX, macroname must consist entirely of letters: no digits, hyphens, underscores, or other special characters. So, we recommend using only letters. However, makeinfo will accept anything consisting of alphanumerics, and (except as the first character) ‘-’. The ‘_’ character is excluded so that macros can be called inside @math without a following space (see section @math: Inserting Mathematical Expressions).

If a macro needs no parameters, you can define it either with an empty list (‘@macro foo {}’) or with no braces at all (‘@macro foo’).

The definition or body of the macro can contain most Texinfo commands, including macro invocations. However, a macro definition that defines another macro does not work in TeX due to limitations in the design of @macro.

In the macro body, instances of a parameter name surrounded by backslashes, as in ‘\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.

To get a single ‘\’ in the macro expansion, use ‘\\’. Any other use of ‘\’ in the body yields a warning.

The newline characters after the @macro line and before the @end macro line are ignored, that is, not included in the macro body. All other whitespace is treated according to the usual Texinfo rules.

To allow a macro to be used recursively, that is, in an argument to a call to itself, you must define it with ‘@rmacro’, like this:

@rmacro rmac {arg}
a\arg\b
@end rmacro
…
@rmac{1@rmac{text}2}

This produces the output ‘a1atextb2b’. With ‘@macro’ instead of ‘@rmacro’, an error message is given.

You can undefine a macro foo with @unmacro foo. It is not an error to undefine a macro that is already undefined. For example:

@unmacro foo

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17.2 Invoking Macros

After a macro is defined (see the previous section), you can invoke (use) it in your document like this:

@macroname {arg1, arg2, …}

and the result will be more or less as if you typed the body of macroname at that spot. For example:

@macro foo {p, q}
Together: \p\ & \q\.
@end macro
@foo{a, b}

produces:

Together: a & b.

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 even when the macro takes no arguments, consistent with other Texinfo commands. For example:

@macro argless {}
No arguments here.
@end macro
@argless{}

produces:

No arguments here.

Passing macro arguments containing commas requires care, since commas also separate the arguments. To include a comma character in an argument, the most reliable method is to use the @comma{} command. For makeinfo, you can also prepend a backslash character, as in ‘\,’, but this does not work with TeX.

It’s not always necessary to worry about commas. To facilitate use of macros, makeinfo implements two rules for automatic quoting in some circumstances:

  1. If a macro takes only one argument, all commas in its invocation are quoted by default. For example:
    @macro TRYME{text}
    @strong{TRYME: \text\}
    @end macro
    
    @TRYME{A nice feature, though it can be dangerous.}
    

    will produce the following output

    TRYME: A nice feature, though it can be dangerous.
    

    And indeed, it can. Namely, makeinfo does not control the number of arguments passed to one-argument macros, so be careful when you invoke them.

  2. 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
    @say{@strong{Yes, I do}, person one}
    

    the comma after ‘Yes’ is implicitly quoted. Here’s another example, with a recursive macro:

    @rmacro cat{a,b}
    \a\\b\
    @end rmacro
    
    @cat{@cat{foo, bar}, baz}
    

    will produce the string ‘foobarbaz’.

  3. Otherwise, a comma should be explicitly quoted, as above, for it to be treated as a part of an argument.

The backslash itself can be quoted in macro arguments with another backslash. For example:

@macname {\\bleh}

will pass the argument ‘\bleh’ to macname.

makeinfo also recognizes ‘\{’ and ‘\}’ sequences for curly braces, but these are not recognized by the implementation in TeX. There should, however, rarely be a need for these, as they are only needed when a macro argument contains unbalanced braces.

If a macro is defined to take exactly one argument, it can be invoked without any braces, taking all of the line after the macro name as the argument. For example:

@macro bar {p}
Twice: \p\ & \p\.
@end macro
@bar aah

produces:

Twice: aah & aah.

In these arguments, there is no escaping of special characters, so each ‘\’ stands for itself.

If a macro is defined to take more than one argument, but is called with only one (in braces), the remaining arguments are set to the empty string, and no error is given. For example:

@macro addtwo {p, q}
Both: \p\\q\.
@end macro
@addtwo{a}

produces simply:

Both: a.

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17.3 Macro Details and Caveats

By design, macro expansion does not happen in the following contexts in makeinfo:

Unfortunately, TeX may do some expansion in these situations, possibly yielding errors.

Also, quite a few macro-related constructs cause problems with TeX; some of the caveats are listed below. Thus, if you get macro-related errors when producing the printed version of a manual, you might try expanding the macros with makeinfo by invoking texi2dvi with the ‘-E’ option (see section Format with texi2dvi). Or, more reliably, eschew Texinfo macros altogether and use a language designed for macro processing, such as M4 (see section External Macro Processors: Line Directives).

The makeinfo implementation also has the following limitations (by design):

In the makeinfo implementation before Texinfo 5.0, ends of lines from expansion of a @macro definition did not end an @-command line-delimited argument (@chapter, @center, etc.). This is no longer the case. For example:

@macro twolines{}
aaa
bbb
@end macro
@center @twolines{}

In the current makeinfo, this is equivalent to:

@center aaa
bbb

with just ‘aaa’ as the argument to @center. In the earlier implementation, it would have been parsed as this:

@center aaa bbb

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17.4 ‘@alias new=existing

The ‘@alias’ command defines a new command to be just like an existing one. This is useful for defining additional markup names, thus preserving additional semantic information in the input even though the output result may be the same.

Write the ‘@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 optional and ignored if present. Thus:

@alias new = existing

For example, if your document contains citations for both books and some other media (movies, for example), you might like to define a macro @moviecite{} that does the same thing as an ordinary @cite{} but conveys the extra semantic information as well. You’d do this as follows:

@alias moviecite = cite

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.

Unfortunately, it’s not possible to alias Texinfo environments; for example, @alias lang=example is an error.

Aliases must not be recursive, directly or indirectly.

It is not advisable to redefine any TeX primitive, plain TeX, or Texinfo command name as an alias. Unfortunately this is a very large set of names, and the possible resulting errors from TeX are unpredictable.

makeinfo will accept the same identifiers for aliases as it does for macro names, that is, alphanumerics and (except as the first character) ‘-’.


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17.5 @definfoenclose: Customized Highlighting

An @definfoenclose command may be used to define a highlighting command for all the non-TeX output formats. A command defined using @definfoenclose marks text by enclosing it in strings that precede and follow the text. You can use this to get closer control of your output.

Presumably, if you define a command with @definfoenclose, you will create a corresponding command for TeX, either in ‘texinfo.tex’, ‘texinfo.cnf’, or within an ‘@iftex’ or ‘@tex’ in your document.

Write a @definfoenclose command at the beginning of a line followed by three comma-separated arguments. The first argument to @definfoenclose is the @-command name (without the @); the second argument is the start delimiter string; and the third argument is the end delimiter string. The latter two arguments enclose the highlighted text in the output.

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 end delimiter string you intended will naturally be (mis)interpreted as the start delimiter string.

If you do a @definfoenclose on the name of a predefined command (such as @emph, @strong, @t, or @i), the enclosure definition will override the built-in definition. We don’t recommend this.

An enclosure command defined this way takes one argument in braces, since it is intended for new markup commands (see section Marking Text, Words and Phrases).

For example, you can write:

@definfoenclose phoo,//,\\

near the beginning of a Texinfo file to define @phoo as an Info formatting command that inserts ‘//’ before and ‘\\’ after the argument to @phoo. You can then write @phoo{bar} wherever you want ‘//bar\\’ highlighted in Info.

For TeX formatting, you could write

@iftex
@global@let@phoo=@i
@end iftex

to define @phoo as a command that causes TeX to typeset the argument to @phoo in italics.

Each definition applies to its own formatter: one for TeX, the other for everything else. The raw TeX commands need to be in ‘@iftex’. @definfoenclose command need not be within ‘@ifinfo’, unless you want to use different definitions for different output formats.

Here is another example: write

@definfoenclose headword, , :

near the beginning of the file, to define @headword as an Info formatting command that inserts nothing before and a colon after the argument to @headword.

@definfoenclose’ definitions must not be recursive, directly or indirectly.


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17.6 External Macro Processors: Line Directives

Texinfo macros (and its other text substitution facilities) work fine in straightforward cases. If your document needs unusually complex processing, however, their fragility and limitations can be a problem. In this case, you may want to use a different macro processor altogether, such as M4 (see Top in M4) or CPP (see Top in The C Preprocessor).

With one exception, Texinfo does not need to know whether its input is “original” source or preprocessed from some other source file. Therefore, you can arrange your build system to invoke whatever programs you like to handle macro expansion or other preprocessing needs. Texinfo does not offer built-in support for any particular preprocessor, since no one program seemed likely to suffice for the requirements of all documents.

The one exception is line numbers in error messages. In that case, the line number should refer to the original source file, whatever it may be. There’s a well-known mechanism for this: the so-called ‘#line’ directive. Texinfo supports this.


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17.6.1 ‘#line’ Directive

An input line such as this:

@hashchar{}line 100 "foo.ptexi"

indicates that the next line was line 100 of the file ‘foo.ptexi’, and so that’s what an error message should refer to. Both M4 (see Preprocessor features in GNU M4) and CPP (see Line Control in The C Preprocessor, and Preprocessor Output in The C Preprocessor) can generate such lines.

The makeinfo program recognizes these lines by default, except within @verbatim blocks (see section @verbatim: Literal Text. Their recognition can be turned off completely with CPP_LINE_DIRECTIVES (see section Other Customization Variables), though there is normally no reason to do so.

For those few programs (M4, CPP, Texinfo) which need to document ‘#line’ directives and therefore have examples which would otherwise match the pattern, the command @hashchar{} can be used (see section Inserting ‘#’ with @hashchar{}). The example line above looks like this in the source for this manual:

@hashchar{}line 100 "foo.ptexi"

The @hashchar command was added to Texinfo in 2013. If you don’t want to rely on it, you can also use @set and @value to insert the literal ‘#’:

@set hash #
@value{hash}line 1 "example.c"

Or, if suitable, a @verbatim environment can be used instead of @example. As mentioned above, #line-recognition is disabled inside verbatim blocks.


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17.6.2 ‘#line’ and TeX

As mentioned, makeinfo recognizes the ‘#line’ directives described in the previous section. However, ‘texinfo.tex’ does not and cannot. Therefore, such a line will be incorrectly typeset verbatim if TeX sees it. The solution is to use makeinfo’s macro expansion options before running TeX. There are three approaches:

One last caveat regarding use with TeX: since the #line directives are not recognized, the line numbers emitted by the @errormsg{} command (see section Conditional Commands), or by TeX itself, are the (incorrect) line numbers from the derived file which TeX is reading, rather than the preprocessor-specified line numbers. This is another example of why we recommend running makeinfo for the best diagnostics (see section makeinfo Advantages).


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17.6.3 ‘#line’ Syntax Details

Syntax details for the ‘#line’ directive: the ‘#’ character can be preceded or followed by whitespace, the word ‘line’ is optional, and the file name can be followed by a whitespace-separated list of integers (these are so-called “flags” output by CPP in some cases). For those who like to know the gory details, the actual (Perl) regular expression which is matched is this:

/^\s*#\s*(line)? (\d+)(( "([^"]+)")(\s+\d+)*)?\s*$/

As far as we’ve been able to tell, the trailing integer flags only occur in conjunction with a filename, so that is reflected in the regular expression.

As an example, the following is a syntactically valid ‘#line’ directive, meaning line 1 of ‘/usr/include/stdio.h’:

@hashchar{} 1 "/usr/include/stdio.h" 2 3 4

Unfortunately, the quoted filename (‘"..."’) has to be optional, because M4 (especially) can often generate ‘#line’ directives within a single file. Since the ‘line’ is also optional, the result is that lines might match which you wouldn’t expect, e.g.,

@hashchar{} 1

The possible solutions are described above (see section #line’ Directive).


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18 Include Files

When a Texinfo processor sees an @include command in a Texinfo file, it processes the contents of the file named by the @include and incorporates them into the output files being created. Include files thus let you keep a single large document as a collection of conveniently small parts.


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18.1 How to Use Include Files

To include another file within a Texinfo file, write the @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:

@include buffers.texi

@-commands are expanded in file names. The one most likely to be useful is @value (see section @set and @value), and even then only in complicated situations.

An included file should simply be a segment of text that you expect to be included as is into the overall or 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 ‘\input texinfo’; if you do, that text is inserted into the output file literally. Likewise, you should not end an included file with a @bye command; nothing after @bye is formatted.

In the long-ago past, you were required to write an @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 @setfilename line exists in an included file, it is ignored.


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18.2 texinfo-multiple-files-update

GNU Emacs Texinfo mode provides the 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 on whether you call it with optional arguments, the command updates only the pointers in the first @node line of the included files or all of them:

M-x texinfo-multiple-files-update

Called without any arguments:

C-u M-x texinfo-multiple-files-update

Called with C-u as a prefix argument:

C-u 8 M-x texinfo-multiple-files-update

Called with a numeric prefix argument, such as C-u 8:

Note the use of the prefix argument in interactive use: with a regular prefix argument, just C-u, the texinfo-multiple-files-update command inserts a master menu; with a numeric prefix argument, such as C-u 8, the command updates every pointer and menu in all the files and then inserts a master menu.


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18.3 Include Files Requirements

If you plan to use the 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 @include commands listing the included files. It should not even include indices, which should be listed in an included file of their own.

Moreover, each of the included files must contain exactly one highest level node (conventionally, @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 a @chapter, an @appendix, or an @unnumbered node. Thus, normally, each included file contains one, and only one, chapter or equivalent-level node.

The outer file should contain only one node, the ‘Top’ node. It should not contain any nodes besides the single ‘Top’ node. The texinfo-multiple-files-update command will not process them.


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18.4 Sample File with @include

Here is an example of an outer Texinfo file with @include files within it before running texinfo-multiple-files-update, which would insert a main or master menu:

\input texinfo @c -*-texinfo-*-
@settitle Include Example
... See section Sample Texinfo Files, for
examples of the rest of the frontmatter ...

@ifnottex
@node Top
@top Include Example
@end ifnottex
@include foo.texinfo
@include bar.texinfo
@include concept-index.texinfo
@bye

An included file, such as ‘foo.texinfo’, might look like this:

@node First
@chapter First Chapter

Contents of first chapter …

The full contents of ‘concept-index.texinfo’ might be as simple as this:

@node Concept Index
@unnumbered Concept Index

@printindex cp

The outer Texinfo source file for The GNU Emacs Lisp Reference Manual is named ‘elisp.texi’. This outer file contains a master menu with 417 entries and a list of 41 @include files.


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18.5 @verbatiminclude file: Include a File Verbatim

You can include the exact contents of a file in the document with the @verbatiminclude command:

@verbatiminclude filename

The contents of filename is printed in a verbatim environment (see section @verbatim: Literal Text). 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 @verbatiminclude within @example (see section @example: Example Text).

The name of the file is taken literally, with a single exception: @value{var} references are expanded. This makes it possible to include files in other directories within a distribution, for instance:

@verbatiminclude @value{top_srcdir}/NEWS

(You still have to get 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 section on @verbatim.


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18.6 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.

References from one file to another were made by referring to the file name as well as the node name. (See section Referring to Other Info Files. Also, see @xref with Four and Five Arguments.)

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 @setfilename line.)

However, because large Info files are now split automatically, it is no longer necessary to keep them small.

Nowadays, multiple Texinfo files are used mostly for large documents, such as The GNU Emacs Lisp Reference Manual, and for projects in which several different people write different sections of a document simultaneously.

In addition, the Info formatting commands have been extended to work with the @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.


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19 Formatting and Printing Hardcopy

Running the texi2dvi or texi2pdf command is the simplest way to create printable output. These commands are installed as part of the Texinfo package.

In more detail, three major shell commands are used to print formatted output from a Texinfo manual: one converts the Texinfo source into something printable, a second sorts indices, and a third actually prints 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 (or some other computing environment).

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.

Details are in the following sections.


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19.1 Use TeX

The typesetting program called TeX is used to format a Texinfo document for printable output. TeX is a very powerful typesetting program and, when used correctly, does an exceptionally good job.

See section Obtaining TeX, for information on how to obtain TeX. It is not included in the Texinfo package, being a vast suite of software in itself.


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19.2 Format with texi2dvi

The texi2dvi program takes care of all the steps for producing a TeX DVI file from a Texinfo document. Similarly, texi2pdf produces a PDF file.

To run texi2dvi or texi2pdf on an input file ‘foo.texi’, do this (where ‘prompt$ ’ is your shell prompt):

prompt$ texi2dvi foo.texi
prompt$ texi2pdf foo.texi

As shown in this example, the input filenames to texi2dvi and texi2pdf must include any extension, such as ‘.texi’. (Under MS-DOS and perhaps in other circumstances, you may need to run ‘sh texi2dvi foo.texi’ instead of relying on the operating system to invoke the shell on the ‘texi2dvi’ script.)

For a list of all the options, run ‘texi2dvi --help’. Some of the options are discussed below.

With the ‘--pdf’ option, texi2dvi produces PDF output instead of DVI (see section PDF Output), by running pdftex instead of tex. Alternatively, the command texi2pdf is an abbreviation for running ‘texi2dvi --pdf’. The command pdftexi2dvi is also provided as a convenience for AUC-TeX (see Top in AUC-TeX), as it prefers to merely prepend ‘pdf’ to DVI producing tools to have PDF producing tools.

With the ‘--dvipdf’ option, texi2dvi produces PDF output by running TeX and then a DVI-to-PDF program: if the DVIPDF environment variable is set, that value is used, else the first program extant among dvipdfmx, dvipdfm, dvipdf, dvi2pdf, dvitopdf. This method generally supports CJK typesetting better than pdftex.

With the ‘--ps’ option, texi2dvi produces PostScript instead of DVI, by running tex and then dvips (see Top in Dvips). (Or the value of the DVIPS environment variable, if set.)

texi2dvi can also be used to process LaTeX files. Normally texi2dvi is able to guess the input file language by its contents and file name extension; however, if it guesses wrong you can explicitly specify the input language using ‘--language=lang’ command line option, where lang is either ‘latex’ or ‘texinfo’.

One useful option to texi2dvi is ‘--command=cmd’. This inserts cmd on a line by itself, after a @setfilename line in a temporary copy of the input file, before running TeX. With this, you can specify different printing formats, such as @smallbook (see section @smallbook: Printing “Small” Books), @afourpaper (see section Printing on A4 Paper), or @pagesizes (see section @pagesizes [width][, height]: Custom Page Sizes), without actually changing the document source. (You can also do this on a site-wide basis with ‘texinfo.cnf’; see section Preparing for TeX).

The option ‘-E’ (equivalently, ‘-e’ and ‘--expand’) does Texinfo macro expansion using makeinfo instead of the TeX implementation (see section Macro Details and Caveats). Each implementation has its own limitations and advantages. If this option is used, no line in the source file may begin with the string @c _texi2dvi or the string @c (_texi2dvi).

texi2dvi takes the ‘--build=mode’ option to specify where the TeX compilation takes place, and, as a consequence, how auxiliary files are treated. The build mode can also be set using the environment variable TEXI2DVI_BUILD_MODE. The valid values for mode are:

local

Compile in the current directory, leaving all the auxiliary files around. This is the traditional TeX use.

tidy

Compile in a local *.t2d directory, where the auxiliary files are left. Output files are copied back to the original file.

Using the ‘tidy’ mode brings several advantages:

On the other hand, because ‘tidy’ compilation takes place in another directory, occasionally TeX won’t be able to find some files (e.g., when using \graphicspath): in that case, use ‘-I’ to specify the additional directories to consider.

clean

Same as ‘tidy’, but remove the auxiliary directory afterwards. Every compilation therefore requires the full cycle.

texi2dvi will use etex (or pdfetex) if it is available, because it runs faster in some cases, and provides additional tracing information when debugging ‘texinfo.tex’. Nevertheless, this extended version of TeX is not required, and the DVI output is identical. (These days, pdftex and pdfetex are exactly the same, but we still run pdfetex to cater to ancient TeX installations.)

texi2dvi attempts to detect auxiliary files output by TeX, either by using the ‘-recorder’ option, or by scanning for ‘\openout’ in the log file that a run of TeX produces. You may control how texi2dvi does this with the TEXI2DVI_USE_RECORDER environment variable. Valid values are:

yes

use the ‘-recorder’ option, no checks.

no

scan for ‘\openout’ in the log file, no checks.

yesmaybe

check whether ‘-recorder’ option is supported, and if yes use it, otherwise check for tracing ‘\openout’ in the log file is supported, and if yes use it, else it is an error.

nomaybe

same as ‘yesmaybe’, except that the ‘\openout’ trace in log file is checked first.

The default is ‘nomaybe’. This environment variable is provided for troubleshooting purposes, and may change or disappear in the future.


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19.3 Format with tex/texindex

You can do the basic formatting of a Texinfo file with the shell command tex followed by the name of the Texinfo file. For example:

tex foo.texi

TeX will produce a DVI file as well as several auxiliary files containing information for indices, cross-references, etc. The DVI file (for DeVice Independent file) can be printed on virtually any device, perhaps after a further conversion (see the previous section).

The 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 tex command, you first need a sorted index to work from. The texindex command sorts indices. (texi2dvi, described in the previous section, runs tex and texindex as necessary.)

tex outputs unsorted index files under names following a standard convention: the name of your main input file with any ‘.texi’ or similar extension replaced by the two letter index name. For example, the raw index output files for the input file ‘foo.texi’ would be, by default, ‘foo.cp’, ‘foo.vr’, ‘foo.fn’, ‘foo.tp’, ‘foo.pg’ and ‘foo.ky’. Those are exactly the arguments to give to texindex.

Instead of specifying all the unsorted index file names explicitly, it’s typical to use ‘??’ as shell wildcards and give the command in this form:

texindex foo.??

This command will run texindex on all the unsorted index files, including any two letter indices that you have defined yourself using @defindex or @defcodeindex. You can safely run ‘texindex foo.??’ even if there are files with two letter extensions that are not index files, such as ‘foo.el’. The texindex command reports but otherwise ignores such files.

For each file specified, texindex generates a sorted index file whose name is made by appending ‘s’ to the input file name; for example, ‘foo.cps’ is made from ‘foo.cp’. The @printindex command looks for a file with that name (see section Printing Indices and Menus). TeX does not read the raw index output file, and texindex does not alter it.

After you have sorted the indices, you need to rerun tex on the Texinfo file. This regenerates the output file, this time with up-to-date index entries.

Finally, you may need to run tex one more time, to get the page numbers in the cross-references correct.

To summarize, this is a five step process. (Alternatively, it’s a one-step process: run texi2dvi; see the previous section.)