path: root/gnu/usr.bin/texinfo/info-files/texi.info-4

This is Info file texi.info, produced by Makeinfo-1.55 from the input
file texi.texi.

   This file documents Texinfo, a documentation system that uses a
single source file to produce both on-line information and a printed
manual.

   Copyright (C) 1988, 1990, 1991, 1992, 1993 Free Software Foundation,
Inc.

   This is the second edition of the Texinfo documentation,
and is consistent with version 2 of `texinfo.tex'.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be stated in a
translation approved by the Free Software Foundation.


File: texi.info,  Node: Node Line Requirements,  Next: First Node,  Prev: Node Line Tips,  Up: node

`@node' Line Requirements
-------------------------

   Here are several requirements for `@node' lines:

   * All the node names for a single Info file must be unique.

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

   * A pointer name must be the name of a node.

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

   * You cannot use any of the Texinfo @-commands in a node name;
     @-commands confuse Info.

     Thus, the beginning of the section called `@chapter' looks like
     this:

          @node  chapter, unnumbered & appendix, makeinfo top, Structuring
          @comment  node-name,  next,  previous,  up
          @section @code{@@chapter}
          @findex chapter

   * You cannot use commas, colons, or apostrophes within a node name;
     these confuse TeX or the Info formatters.

     For example, the following is a section title:

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

     The corresponding node name is:

          unnumberedsec appendixsec heading

   * Case is significant.


File: texi.info,  Node: First Node,  Next: makeinfo top command,  Prev: Node Line Requirements,  Up: node

The First Node
--------------

   The first node of a Texinfo file is the `Top' node, except in an
included file (*note Include Files::.).

   The `Top' node (which must be named `top' or `Top') should have as
its `Up' and `Previous' nodes the name of a node in another file, where
there is a menu that leads to this file.  Specify the file name in
parentheses.  If the file is to be installed directly in the Info
directory file, use `(dir)' as the parent of the `Top' node; this is
short for `(dir)top', and specifies the `Top' node in the `dir' file,
which contains the main menu for Info.  For example, the `@node Top'
line of this manual looks like this:

     @node Top, Overview, (dir), (dir)

(You may use the Texinfo updating commands or the `makeinfo' utility to
insert these `Next' and `(dir)' pointers automatically.)

   *Note Install an Info File::, for more information about installing
an Info file in the `info' directory.

   The `Top' node contains the main or master menu for the document.


File: texi.info,  Node: makeinfo top command,  Next: Top Node Summary,  Prev: First Node,  Up: node

The `@top' Sectioning Command
-----------------------------

   A special sectioning command, `@top', has been created for use with
the `@node Top' line.  The `@top' sectioning command tells `makeinfo'
that it marks the `Top' node in the file.  It provides the information
that `makeinfo' needs to insert node pointers automatically.  Write the
`@top' command at the beginning of the line immediately following the
`@node Top' line.  Write the title on the remaining part of the same
line as the `@top' command.

   In Info, the `@top' sectioning command causes the title to appear on
a line by itself, with a line of asterisks inserted underneath.

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

   Whatever sectioning command follows an `@node Top' line, whether it
be `@top' or `@chapter', the `@node Top' line and the immediately
following line and any additional text must be enclosed between
`@ifinfo' and `@end ifinfo' commands.  (*Note Conditionals::.)  This
prevents the title and the accompanying text from appearing in printed
output.  Write the `@ifinfo' command before the `@node' line and write
the `@end ifinfo' command after the `@top' or other sectioning command
and after any additional text.  (You can write the `@end ifinfo'
command after the `@end menu' command if you like.)


File: texi.info,  Node: Top Node Summary,  Prev: makeinfo top command,  Up: node

The `Top' Node Summary
----------------------

   You can help readers by writing a summary in the `Top' node, after
the `@top' line, before the main or master menu.  The summary should
briefly describe the Info file.  You should also write the version
number of the program to which the manual applies in this section.  This
helps the reader keep track of which manual is for which version of the
program.  If the manual changes more frequently than the program or is
independent of it, you should also include an edition number for the
manual.  (The title page should also contain this information: see
*Note `@titlepage': titlepage.)

   Put the whole of the `Top' node, including the `@top' sectioning
command line if you have one, between `@ifinfo' and `@end ifinfo' so
none of the text appears in the printed output (*note Conditionally
Visible Text: Conditionals.).  (You may want to repeat the brief
description from the `Top' node within `@iftex' ... `@end iftex' at the
beginning of the first chapter, for those who read the printed manual.)


File: texi.info,  Node: makeinfo Pointer Creation,  Prev: node,  Up: Nodes

Creating Pointers with `makeinfo'
=================================

   The `makeinfo' program has a feature for automatically creating node
pointers for a hierarchically organized file that lacks them.

   When you take advantage of this feature, you do not need to write the
`Next', `Previous', and `Up' pointers after the name of a node.
However, you must write a sectioning command, such as `@chapter' or
`@section', on the line immediately following each truncated `@node'
line.  You cannot write a comment line after a node line; the section
line must follow it immediately.

   In addition, you must follow the `Top' `@node' line with a line
beginning with `@top' to mark the `Top' node in the file. *Note `@top':
makeinfo top.

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

   This node pointer insertion feature in `makeinfo' is an alternative
to the menu and pointer creation and update commands in Texinfo mode.
(*Note Updating Nodes and Menus::.)  It is especially helpful to people
who do not use GNU Emacs for writing Texinfo documents.


File: texi.info,  Node: Menus,  Next: Cross References,  Prev: Nodes,  Up: Top

Menus
*****

   "Menus" contain pointers to subordinate nodes.(1) In Info, you use
menus to go to such nodes.  Menus have no effect in printed manuals and
do not appear in them.

   By convention, a menu is put at the end of a node since a reader who
uses the menu may not see text that follows it.

   A node that has a menu should *not* contain much text.  If you have
a lot of text and a menu, move most of the text into a new subnode--all
but a few lines.

* Menu:

* Menu Location::               Put a menu in a short node.
* Writing a Menu::              What is a menu?
* Menu Parts::                  A menu entry has three parts.
* Less Cluttered Menu Entry::   Two part menu entry.
* Menu Example::                Two and three part menu entries.
* Other Info Files::            How to refer to a different Info file.

   ---------- Footnotes ----------

   (1)  Menus can carry you to any node, regardless of the hierarchical
structure; even to nodes in a different Info file.  However, the GNU
Emacs Texinfo mode updating commands work only to create menus of
subordinate nodes.  Conventionally, cross references are used to refer
to other nodes.


File: texi.info,  Node: Menu Location,  Next: Writing a Menu,  Up: Menus

Menus Need Short Nodes
======================

   A reader can easily see a menu that is close to the beginning of the
node.  The node should be short.  As a practical matter, you should
locate a menu within 20 lines of the beginning of the node.  Otherwise,
a reader with a terminal that displays only a few lines may miss the
menu and its associated text.

   The short text before a menu may look awkward in a printed manual.
To avoid this, you can write a menu near the beginning of its node and
follow the menu by an `@node' line, and then an `@heading' line located
within `@ifinfo' and `@end ifinfo'.  This way, the menu, `@node' line,
and title appear only in the Info file, not the printed document.

   For example, the preceding two paragraphs follow an Info-only menu,
`@node' line, and heading, and look like this:

     @menu
     * Menu Location::             Put a menu in a short node.
     * Writing a Menu::            What is a menu?
     * Menu Parts::                A menu entry has three parts.
     * Less Cluttered Menu Entry:: Two part menu entry.
     * Menu Example::              Two and three part entries.
     * Other Info Files::          How to refer to a different
                                     Info file.
     @end menu
     
     @node Menu Location, Writing a Menu,  , Menus
     @ifinfo
     @heading Menus Need Short Nodes
     @end ifinfo

   The Texinfo file for this document contains more than a dozen
examples of this procedure.  One is at the beginning of this chapter;
another is at the beginning of the "Cross References" chapter.


File: texi.info,  Node: Writing a Menu,  Next: Menu Parts,  Prev: Menu Location,  Up: Menus

Writing a Menu
==============

   A menu consists of an `@menu' command on a line by itself followed
by menu entry lines or menu comment lines and then 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
is a menu comment line that appears in the Info file.  In the example
above, the line `Larger Units of Text' is a menu comment line; the two
lines starting with `* ' are menu entries.


File: texi.info,  Node: Menu Parts,  Next: Less Cluttered Menu Entry,  Prev: Writing a Menu,  Up: Menus

The Parts of a Menu
===================

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

  1. The menu entry name.

  2. The name of the node (required).

  3. A description of the item.

   The template for a menu entry looks like this:

     * MENU-ENTRY-NAME: NODE-NAME.   DESCRIPTION

   Follow the menu entry name with a single colon and follow the node
name with tab, comma, period, or newline.

   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.

   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.  The description, which
is optional, can spread over two or more lines.  A useful description
complements the node name rather than repeats it.


File: texi.info,  Node: Less Cluttered Menu Entry,  Next: Menu Example,  Prev: Menu Parts,  Up: Menus

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

   You should use the node name for the menu entry name whenever
possible, since it reduces visual clutter in the menu.


File: texi.info,  Node: Menu Example,  Next: Other Info Files,  Prev: Less Cluttered Menu Entry,  Up: Menus

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 (*note Referring
to Other Info Files: Other Info Files.).


File: texi.info,  Node: Other Info Files,  Prev: Menu Example,  Up: Menus

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.  In this case, you should use the three-part menu
entry format, which saves the reader from having to type the file name.

   The format looks like this:

     @menu
     * FIRST-ENTRY-NAME:(FILENAME)NODENAME.     DESCRIPTION
     * SECOND-ENTRY-NAME:(FILENAME)SECOND-NODE. DESCRIPTION
     @end menu

   For example, to refer directly to the `Outlining' and `Rebinding'
nodes in the `Emacs Manual', you would write a menu like this:

     @menu
     * Outlining: (emacs)Outline Mode. The major mode for
                                       editing outlines.
     * Rebinding: (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.

   The `dir' file that contains the main menu for Info has menu entries
that list only file names.  These take you directly to the `Top' nodes
of each Info document.  (*Note Install an Info File::.)

   For example:

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

(The `dir' top level directory for the Info system is an Info file, not
a Texinfo file, but a menu entry looks the same in both types of file.)

   Note that 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.


File: texi.info,  Node: Cross References,  Next: Marking Text,  Prev: Menus,  Up: Top

Cross References
****************

   "Cross references" are used to refer the reader to other parts of the
same or different Texinfo files.  In Texinfo, nodes are the places to
which cross references can refer.

* Menu:

* References::                  What cross references are for.
* Cross Reference Commands::    A summary of the different commands.
* Cross Reference Parts::       A cross reference has several parts.
* xref::                        Begin a reference with `See' ...
* Top Node Naming::             How to refer to the beginning of another file.
* ref::                         A reference for the last part of a sentence.
* pxref::                       How to write a parenthetical cross reference.
* inforef::                     How to refer to an Info-only file.


File: texi.info,  Node: References,  Next: Cross Reference Commands,  Up: Cross References

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 on-line 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.  (*note Some advanced Info commands:
(info)Help-Adv.)

   The various cross reference commands use nodes to define cross
reference locations.  This is evident in Info, in which a cross
reference takes you to the specified node.  TeX also uses nodes to
define cross reference locations, but the action is less obvious.  When
TeX generates a DVI file, it records nodes' page numbers and uses the
page numbers in making references.  Thus, if you are writing a manual
that will only be printed, and will not be used on-line, you must
nonetheless write `@node' lines to name the places to which you make
cross references.


File: texi.info,  Node: Cross Reference Commands,  Next: Cross Reference Parts,  Prev: References,  Up: Cross References

Different Cross Reference Commands
==================================

   There are four different cross reference commands:

`@xref'
     Used to start a sentence in the printed manual saying `See ...' or
     an entry in the Info file saying `*Note ...'.

`@ref'
     Used within or, more often, at the end of a sentence; same as
     `@xref' for Info; produces just the reference in the printed
     manual without a preceding `See'.

`@pxref'
     Used within parentheses to make a reference that suits both an Info
     file and a printed book.  Starts with a lower case `see' within the
     printed manual. (`p' is for `parenthesis'.)

`@inforef'
     Used to make a reference to an Info file for which there is no
     printed manual.

(The `@cite' command is used to make references to books and manuals
for which there is no corresponding Info file and, therefore, no node
to which to point.   *Note `@cite': cite.)


File: texi.info,  Node: Cross Reference Parts,  Next: xref,  Prev: Cross Reference Commands,  Up: Cross References

Parts of a Cross Reference
==========================

   A cross reference command requires only one argument, which is the
name of the node to which it refers.  But a cross reference command may
contain up to four additional arguments.  By using these arguments, you
can provide a cross reference name for Info, a topic description or
section title for the printed output, the name of a different Info
file, and the name of a different printed manual.

   Here is a simple cross reference example:

     @xref{Node name}.

which produces

     *Note Node name::.

and

     See Section NNN [Node name], page PPP.

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

     @xref{Node name, Cross Reference Name, Particular Topic,
     info-file-name, A Printed Manual}, for details.

which produces

     *Note Cross Reference Name: (info-file-name)Node name,
     for details.

in Info and

     See section "Particular Topic" in A Printed Manual, for details.

in a printed book.

   The five possible arguments for a cross reference are:

  1. The node name (required).  This is the node 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.

  2. The cross reference name for the Info reference, if it is to be
     different from the node name.  If you include this argument, it
     argument becomes the first part of the cross reference. It is
     usually omitted.

  3. A topic description or section name.  Often, this is the title of
     the section.  This is used as the name of the reference in the
     printed manual.  If omitted, the node name is used.

  4. The name of the Info file in which the reference is located, if it
     is different from the current file.

  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, CROSS-REFERENCE-NAME, TITLE-OR-TOPIC,
     INFO-FILE-NAME, PRINTED-MANUAL-TITLE}.

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

   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.

   You can write cross reference commands within a paragraph, but note
how Info and TeX format the output of each of the various commands:
write `@xref' at the beginning of a sentence; write `@pxref' only
within parentheses, and so on.


File: texi.info,  Node: xref,  Next: Top Node Naming,  Prev: Cross Reference Parts,  Up: Cross References

`@xref'
=======

   The `@xref' command generates a cross reference for the beginning of
a sentence.  The Info formatting commands convert it into an Info cross
reference, which the Info `f' command can use to bring you directly to
another node.  The TeX typesetting commands convert it into a page
reference, or a reference to another book or manual.

* Menu:

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


File: texi.info,  Node: Reference Syntax,  Next: One Argument,  Up: xref

What a Reference Looks Like and Requires
----------------------------------------

   Most often, an Info cross reference looks like this:

     *Note NODE-NAME::.

or like this

     *Note CROSS-REFERENCE-NAME: NODE-NAME.

In TeX, a cross reference looks like this:

     See Section SECTION-NUMBER [NODE-NAME], page PAGE.

or like this

     See Section SECTION-NUMBER [TITLE-OR-TOPIC], page PAGE.

   The `@xref' command does not generate a period or comma to end the
cross reference in either the Info file or the printed output.  You
must write that period or comma yourself; otherwise, Info will not
recognize the end of the reference.  (The `@pxref' command works
differently.  *Note `@pxref': pxref.)

     *Please note:* A period or comma *must* follow the closing brace
     of an `@xref'.  It is required to terminate the cross reference.
     This period or comma will appear in the output, both in the Info
     file and in the printed manual.

   `@xref' must refer to an Info node by name.  Use `@node' to define
the node (*note Writing a Node::.).

   `@xref' is followed by several arguments inside braces, separated by
commas.  Whitespace before and after these commas is ignored.

   A cross reference requires only the name of a node; but it may
contain up to four additional arguments.  Each of these variations
produces a cross reference that looks somewhat different.

     *Please note:* Commas separate arguments in a cross reference;
     avoid including them in the title or other part lest the formatters
     mistake them for separators.


File: texi.info,  Node: One Argument,  Next: Two Arguments,  Prev: Reference Syntax,  Up: xref

`@xref' with One Argument
-------------------------

   The simplest form of `@xref' takes one argument, the name of another
node in the same Info file.    The Info formatters produce output that
the Info readers can use to jump to the reference; TeX produces output
that specifies the page and section number for you.

For example,

     @xref{Tropical Storms}.

produces

     *Note Tropical Storms::.

and

     See Section 3.1 [Tropical Storms], page 24.

(Note that in the preceding example the closing brace is followed by a
period.)

   You can write a clause after the cross reference, like this:

     @xref{Tropical Storms}, for more info.

which produces

     *Note Tropical Storms::, for more info.

     See Section 3.1 [Tropical Storms], page 24, for more info.

(Note that in the preceding example the closing brace is followed by a
comma, and then by the clause, which is followed by a period.)


File: texi.info,  Node: Two Arguments,  Next: Three Arguments,  Prev: One Argument,  Up: xref

`@xref' with Two Arguments
--------------------------

   With two arguments, the second is used as the name of the Info cross
reference, while the first is still the name of the node to which the
cross reference points.

The template is like this:

     @xref{NODE-NAME, CROSS-REFERENCE-NAME}.

For example,

     @xref{Electrical Effects, Lightning}.

produces:

     *Note Lightning: Electrical Effects.

and

     See Section 5.2 [Electrical Effects], page 57.

(Note that in the preceding example the closing brace is followed by a
period; and that the node name is printed, not the cross reference
name.)

   You can write a clause after the cross reference, like this:

     @xref{Electrical Effects, Lightning}, for more info.

which produces
     *Note Lightning: Electrical Effects, for more info.

and

     See Section 5.2 [Electrical Effects], page 57, for more info.

(Note that in the preceding example the closing brace is followed by a
comma, and then by the clause, which is followed by a period.)


File: texi.info,  Node: Three Arguments,  Next: Four and Five Arguments,  Prev: Two Arguments,  Up: xref

`@xref' with Three Arguments
----------------------------

   A third argument replaces the node name in the TeX output.  The third
argument should be the name of the section in the printed output, or
else state the topic discussed by that section.  Often, you will want to
use initial upper case letters so it will be easier to read when the
reference is printed.  Use a third argument when the node name is
unsuitable because of syntax or meaning.

   Remember to avoid placing a comma within the title or topic section
of a cross reference, or within any other section.  The formatters
divide cross references into arguments according to the commas; a comma
within a title or other section will divide it into two arguments.  In
a reference, you need to write a title such as "Clouds, Mist, and Fog"
without the commas.

   Also, remember to write a comma or period after the closing brace of
a `@xref' to terminate the cross reference.  In the following examples,
a clause follows a terminating comma.

The template is like this:

     @xref{NODE-NAME, CROSS-REFERENCE-NAME, TITLE-OR-TOPIC}.

For example,

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

produces

     *Note Lightning: Electrical Effects, for details.

and

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

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

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

produces

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

and

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

   As a practical matter, it is often best to write cross references
with just the first argument if the node name and the section title are
the same, and with the first and third arguments if the node name and
title are different.

   Here are several examples from `The GAWK Manual':

     @xref{Sample Program}.
     @xref{Glossary}.
     @xref{Case-sensitivity, ,Case-sensitivity in Matching}.
     @xref{Close Output, , Closing Output Files and Pipes},
        for more information.
     @xref{Regexp, , Regular Expressions as Patterns}.


File: texi.info,  Node: Four and Five Arguments,  Prev: Three Arguments,  Up: xref

`@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.

   Remember that a comma or period must follow the closing brace of an
`@xref' command to terminate the cross reference.  In the following
examples, a clause follows a terminating comma.

The template is:

     @xref{NODE-NAME, CROSS-REFERENCE-NAME, TITLE-OR-TOPIC,
     INFO-FILE-NAME, PRINTED-MANUAL-TITLE}.

For example,

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

produces

     *Note Lightning: (weather)Electrical Effects, for details.

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, for details.

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

   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.

The template looks like this:

     @xref{NODE-NAME, , TITLE-OR-TOPIC, INFO-FILE-NAME,
     PRINTED-MANUAL-TITLE}, for details.

which produces

     *Note TITLE-OR-TOPIC: (INFO-FILE-NAME)NODE-NAME, for details.

and

     See section TITLE-OR-TOPIC in PRINTED-MANUAL-TITLE, for details.

For example,

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

produces

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

and

     See section "Thunder and Lightning" in An Introduction to
     Meteorology, for details.

   On rare occasions, you may want to refer to another Info file that
is within a single printed manual--when multiple Texinfo files are
incorporated into the same TeX run but make separate Info files.  In
this case, you need to specify only the fourth argument, and not the
fifth.


File: texi.info,  Node: Top Node Naming,  Next: ref,  Prev: xref,  Up: Cross References

Naming a `Top' Node
===================

   In a cross reference, you must always name a node.  This means that
in order to refer to a whole manual, you must identify the `Top' node by
writing it as the first argument to the `@xref' command.  (This is
different from the way you write a menu entry; see *Note Referring to
Other Info Files: Other Info Files.)  At the same time, to provide a
meaningful section topic or title in the printed cross reference
(instead of the word `Top'), you must write an appropriate entry for
the third argument to the `@xref' command.

Thus, to make a cross reference to `The GNU Make Manual', write:

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

which produces

     *Note Overview: (make)Top.

and

     See section "Overview" in The GNU Make Manual.

In this example, `Top' is the name of the first node, and `Overview' is
the name of the first section of the manual.


File: texi.info,  Node: ref,  Next: pxref,  Prev: Top Node Naming,  Up: Cross References

`@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, see @ref{Hurricanes}.

produces

     For more information, see *Note Hurricanes.

and

     For more information, see Section 8.2 [Hurricanes], page 123.

   The `@ref' command sometimes leads writers to express themselves in
a manner that is suitable for a printed manual but looks awkward in the
Info format.  Bear in mind that your audience will be using both the
printed and the Info format.

For example,

     Sea surges are described in @ref{Hurricanes}.

produces

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

in a printed document, and the following in Info:

     Sea surges are described in *Note Hurricanes::.

     *Caution:* You *must* write a period or comma immediately after an
     `@ref' command with two or more arguments.  Otherwise, Info will
     not find the end of the cross reference entry and its attempt to
     follow the cross reference will fail.  As a general rule, you
     should write a period or comma after every `@ref' command.  This
     looks best in both the printed and the Info output.


File: texi.info,  Node: pxref,  Next: inforef,  Prev: ref,  Up: Cross References

`@pxref'
========

   The parenthetical reference command, `@pxref', is nearly the same as
`@xref', but you use it *only* inside parentheses and you do *not* type
a comma or period after the command's closing brace.  The command
differs from `@xref' in two ways:

  1. TeX typesets the reference for the printed manual with a lower case
     `see' rather than an upper case `See'.

  2. The Info formatting commands automatically end the reference with a
     closing colon or period.

   Because one type of formatting automatically inserts closing
punctuation and the other does not, you should use `@pxref' *only*
inside parentheses as part of another sentence.  Also, you yourself
should not insert punctuation after the reference, as you do with
`@xref'.

   `@pxref' is designed so that the output looks right and works right
between parentheses both in printed output and in an Info file.  In a
printed manual, a closing comma or period should not follow a cross
reference within parentheses; such punctuation is wrong.  But in an
Info file, suitable closing punctuation must follow the cross reference
so Info can recognize its end.  `@pxref' spares you the need to use
complicated methods to put a terminator into one form of the output and
not the other.

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

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

which produces

     ... storms cause flooding (*Note Hurricanes::) ...

and

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

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

     ... (@pxref{NODE-NAME, CROSS-REFERENCE-NAME}) ...

which produces

     ... (*Note CROSS-REFERENCE-NAME: NODE-NAME.) ...

and

     ... (see Section NNN [NODE-NAME], page PPP) ...

   `@pxref' can be used with up to five arguments just like `@xref'
(*note `@xref': xref.).

     *Please note:* Use `@pxref' only as a parenthetical reference.  Do
     not try to use `@pxref' as a clause in a sentence.  It will look
     bad in either the Info file, the printed output, or both.

     Also, parenthetical cross references look best at the ends of
     sentences.  Although you may write them in the middle of a
     sentence, that location breaks up the flow of text.


File: texi.info,  Node: inforef,  Prev: pxref,  Up: Cross References

`@inforef'
==========

   `@inforef' is used for cross references to Info files for which
there are no printed manuals.  Even in a printed manual, `@inforef'
generates a reference directing the user to look in an Info file.

   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.

Separate the arguments with commas, as with `@xref'.  Also, you must
terminate the reference with a comma or period after the `}', as you do
with `@xref'.

The template is:

     @inforef{NODE-NAME, CROSS-REFERENCE-NAME, INFO-FILE-NAME},

Thus,

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

produces

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

and

     See Info file `info', node `Expert', for more information.

Similarly,

     @inforef{Expert, , info}, for more information.

produces

     *Note (info)Expert::, for more information.

and

     See Info file `info', node `Expert', for more information.

   The converse of `@inforef' is `@cite', which is used to refer to
printed works for which no Info form exists.  *Note `@cite': cite.


File: texi.info,  Node: Marking Text,  Next: Quotations and Examples,  Prev: Cross References,  Up: Top

Marking 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.

* Menu:

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


File: texi.info,  Node: Indicating,  Next: Emphasis,  Up: Marking Text

Indicating Definitions, Commands, etc.
======================================

   Texinfo has commands for indicating just what kind of object a piece
of text refers to.  For example, metasyntactic variables are marked by
`@var', and code by `@code'.  Since the pieces of text are labelled by
commands that tell what kind of object they are, it is easy to change
the way the Texinfo formatters prepare such text.  (Texinfo is an
*intentional* formatting language rather than a *typesetting*
formatting language.)

   For example, in a printed manual, code is usually illustrated in a
typewriter font; `@code' tells TeX to typeset this text in this font.
But it would be easy to change the way TeX highlights code to use
another font, and this change would not effect how keystroke examples
are highlighted.  If straight typesetting commands were used in the body
of the file and you wanted to make a change, you would need to check
every single occurrence to make sure that you were changing code and
not something else that should not be changed.

* Menu:

* Useful Highlighting::         Highlighting provides useful information.
* code::                        How to indicate code.
* kbd::                         How to show keyboard input.
* key::                         How to specify keys.
* samp::                        How to show a literal sequence of characters.
* var::                         How to indicate a metasyntactic variable.
* file::                        How to indicate the name of a file.
* dfn::                         How to specify a definition.
* cite::                        How to refer to a book that is not in Info.


File: texi.info,  Node: Useful Highlighting,  Next: code,  Up: Indicating

Highlighting Commands are Useful
--------------------------------

   The highlighting commands can be used to generate useful information
from the file, such as lists of functions or file names.  It is
possible, for example, to write a program in Emacs Lisp (or a keyboard
macro) to insert an index entry after every paragraph that contains
words or phrases marked by a specified command.  You could do this to
construct an index of functions if you had not already made the entries.

   The commands serve a variety of purposes:

`@code{SAMPLE-CODE}'
     Indicate text that is a literal example of a piece of a program.

`@kbd{KEYBOARD-CHARACTERS}'
     Indicate keyboard input.

`@key{KEY-NAME}'
     Indicate the conventional name for a key on a keyboard.

`@samp{TEXT}'
     Indicate text that is a literal example of a sequence of
     characters.

`@var{METASYNTACTIC-VARIABLE}'
     Indicate a metasyntactic variable.

`@file{FILE-NAME}'
     Indicate the name of a file.

`@dfn{TERM}'
     Indicate the introductory or defining use of a term.

`@cite{REFERENCE}'
     Indicate the name of a book.


File: texi.info,  Node: code,  Next: kbd,  Prev: Useful Highlighting,  Up: Indicating

`@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.
Also, you should use `@code' for the name of a program, such as `diff',
that is a name used in the machine. (You should write the name of a
program in the ordinary text font if you regard it as a new English
word, such as `Emacs' or `Bison'.)

   Use `@code' for environment variables such as `TEXINPUTS', and other
variables.

   Use `@code' for command names in command languages that resemble
programming languages, such as Texinfo or the shell.  For example,
`@code' and `@samp' are produced by writing `@code{@@code}' and
`@code{@@samp}' in the Texinfo source, respectively.

   Note, however, that you should not use `@code' for shell options
such as `-c' when such options stand alone. (Use `@samp'.) Also, an
entire shell command often looks better if written using `@samp' rather
than `@code'.  In this case, the rule is to choose the more pleasing
format.

   It is incorrect to alter the case of a word inside an `@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 written all in lower case, you should rearrange the
sentence.

   Do not use the `@code' command for a string of characters shorter
than a syntactic token.  If you are writing about `TEXINPU', which is
just a part of the name for the `TEXINPUTS' environment variable, you
should use `@samp'.

   In particular, you should not use the `@code' command when writing
about the characters used in a token; do not, for example, use `@code'
when you are explaining what letters or printable symbols can be used
in the names of functions.  (Use `@samp'.)  Also, you should not use
`@code' to mark text that is considered input to programs unless the
input is written in a language that is like a programming language.
For example, you should not use `@code' for the keystroke commands of
GNU Emacs (use `@kbd' instead) although you may use `@code' for the
names of the Emacs Lisp functions that the keystroke commands invoke.

   In the printed manual, `@code' causes TeX to typeset the argument in
a typewriter face.  In the Info file, it causes the Info formatting
commands to use single quotation marks around the text.

   For example,

     Use @code{diff} to compare two files.

produces this in the printed manual:

     Use `diff' to compare two files.


File: texi.info,  Node: kbd,  Next: key,  Prev: code,  Up: Indicating

`@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}

   The `@kbd' command has the same effect as `@code' in Info, but may
produce a different font in a printed manual.

   You can embed another @-command inside the braces of an `@kbd'
command.  Here, for example, is the way to describe a command that
would be described more verbosely as "press an `r' and then press the
RET key":

     @kbd{r @key{RET}}

This produces: `r RET'

   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 really want to mention a space character as one of the characters of
input, write `@key{SPC}' for it.)


File: texi.info,  Node: key,  Next: samp,  Prev: kbd,  Up: Indicating

`@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' you would type:

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

   Here is a list of the recommended names for keys; they are all in
upper case:

    SPC
          Space

    RET
          Return

    LFD
          Linefeed

    TAB
          Tab

    BS
          Backspace

    ESC
          Escape

    DEL
          Delete

    SFT
          Shift

    CTL
          Control

    META
          Meta

   There are subtleties to handling words like `meta' or `ctl' that are
names of shift keys.  When mentioning a character in which the shift
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 shift key in
isolation, use the `@key' command.  For example, write `@kbd{Meta-a}'
to produce `Meta-a' and `@key{META}' to produce META.  This is because
`Meta-a' refers to keys that you press on a keyboard, but META refers
to a key without implying that you press it.  In short, use `@kbd' for
what you do, and use `@key' for what you talk about: "Press `@kbd{M-a}'
to move point to the beginning of the sentence.  The `@key{META}' key
is often in the lower left of the keyboard."


File: texi.info,  Node: samp,  Next: var,  Prev: key,  Up: Indicating

`@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' is more appropriate.  Use `@samp' for the names
of command-line options.  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', or `@key'.

   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'.