path: root/doc/emacs/text.texi

@c -*- coding: utf-8 -*-
@c This is part of the Emacs manual.
@c Copyright (C) 1985--1987, 1993--1995, 1997, 2000--2021 Free Software
@c Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Text
@chapter Commands for Human Languages
@cindex text
@cindex manipulating text

  This chapter describes Emacs commands that act on @dfn{text}, by
which we mean sequences of characters in a human language (as opposed
to, say, a computer programming language).  These commands act in ways
that take into account the syntactic and stylistic conventions of
human languages: conventions involving words, sentences, paragraphs,
and capital letters.  There are also commands for @dfn{filling}, which
means rearranging the lines of a paragraph to be approximately equal
in length.  These commands, while intended primarily for editing text,
are also often useful for editing programs.

  Emacs has several major modes for editing human-language text.  If
the file contains ordinary text, use Text mode, which customizes Emacs
in small ways for the syntactic conventions of text.  Outline mode
provides special commands for operating on text with an outline
structure.  @xref{Outline Mode}.

  Org mode extends Outline mode and turns Emacs into a full-fledged
organizer: you can manage TODO lists, store notes and publish them in
many formats.
@ifinfo
@xref{Top, The Org Manual,,org, The Org Manual}.
@end ifinfo
@ifnotinfo
See the Org Info manual, which is distributed with Emacs.
@end ifnotinfo

  Emacs has other major modes for text which contains embedded
commands, such as @TeX{} and @LaTeX{} (@pxref{TeX Mode}); HTML and
SGML (@pxref{HTML Mode}); XML
@ifinfo
(@pxref{Top,The nXML Mode Manual,,nxml-mode, nXML Mode});
@end ifinfo
@ifnotinfo
(see the nXML mode Info manual, which is distributed with Emacs);
@end ifnotinfo
and Groff and Nroff (@pxref{Nroff Mode}).

@cindex ASCII art
  If you need to edit ASCII art pictures made out of text characters,
use Picture mode, a special major mode for editing such pictures.
@iftex
@xref{Picture Mode,,, emacs-xtra, Specialized Emacs Features}.
@end iftex
@ifnottex
@xref{Picture Mode}.
@end ifnottex

@ifinfo
@cindex skeletons
@cindex templates
@cindex autotyping
@cindex automatic typing
  The automatic typing features may be useful when writing text.
@xref{Top, Autotyping, The Autotype Manual, autotype}.
@end ifinfo

@menu
* Words::               Moving over and killing words.
* Sentences::           Moving over and killing sentences.
* Paragraphs::          Moving over paragraphs.
* Pages::               Moving over pages.
* Quotation Marks::     Inserting quotation marks.
* Filling::             Filling or justifying text.
* Case::                Changing the case of text.
* Text Mode::           The major modes for editing text files.
* Outline Mode::        Editing outlines.
* Org Mode::            The Emacs organizer.
* TeX Mode::            Editing TeX and LaTeX files.
* HTML Mode::           Editing HTML and SGML files.
* Nroff Mode::          Editing input to the nroff formatter.
* Enriched Text::       Editing text enriched with fonts, colors, etc.
* Text Based Tables::   Commands for editing text-based tables.
* Two-Column::          Splitting text columns into separate windows.
@end menu

@node Words
@section Words
@cindex words
@cindex Meta commands and words

  Emacs defines several commands for moving over or operating on
words:

@table @kbd
@item M-f
Move forward over a word (@code{forward-word}).
@item M-b
Move backward over a word (@code{backward-word}).
@item M-d
Kill up to the end of a word (@code{kill-word}).
@item M-@key{DEL}
Kill back to the beginning of a word (@code{backward-kill-word}).
@item M-@@
Set mark at the end of the next word (@code{mark-word}).
@item M-t
Transpose two words or drag a word across others
(@code{transpose-words}).
@end table

  Notice how these keys form a series that parallels the character-based
@kbd{C-f}, @kbd{C-b}, @kbd{C-d}, @key{DEL} and @kbd{C-t}.  @kbd{M-@@} is
cognate to @kbd{C-@@}, which is an alias for @kbd{C-@key{SPC}}.

@kindex M-f
@kindex M-b
@findex forward-word
@findex backward-word
  The commands @kbd{M-f} (@code{forward-word}) and @kbd{M-b}
(@code{backward-word}) move forward and backward over words.  These
@key{Meta}-based key sequences are analogous to the key sequences
@kbd{C-f} and @kbd{C-b}, which move over single characters.  The
analogy extends to numeric arguments, which serve as repeat counts.
@kbd{M-f} with a negative argument moves backward, and @kbd{M-b} with
a negative argument moves forward.  Forward motion stops right after
the last letter of the word, while backward motion stops right before
the first letter.

@kindex M-d
@findex kill-word
  @kbd{M-d} (@code{kill-word}) kills the word after point.  To be
precise, it kills everything from point to the place @kbd{M-f} would
move to.  Thus, if point is in the middle of a word, @kbd{M-d} kills
just the part after point.  If some punctuation comes between point
and the next word, it is killed along with the word.  (If you wish to
kill only the next word but not the punctuation before it, simply do
@kbd{M-f} to get the end, and kill the word backwards with
@kbd{M-@key{DEL}}.)  @kbd{M-d} takes arguments just like @kbd{M-f}.

@findex backward-kill-word
@kindex M-DEL
  @kbd{M-@key{DEL}} (@code{backward-kill-word}) kills the word before
point.  It kills everything from point back to where @kbd{M-b} would
move to.  For instance, if point is after the space in @w{@samp{FOO,
BAR}}, it kills @w{@samp{FOO, }}.  If you wish to kill just
@samp{FOO}, and not the comma and the space, use @kbd{M-b M-d} instead
of @kbd{M-@key{DEL}}.

@c Don't index M-t and transpose-words here, they are indexed in
@c fixit.texi, in the node "Transpose".
@c @kindex M-t
@c @findex transpose-words
  @kbd{M-t} (@code{transpose-words}) exchanges the word before or
containing point with the following word.  The delimiter characters between
the words do not move.  For example, @w{@samp{FOO, BAR}} transposes into
@w{@samp{BAR, FOO}} rather than @samp{@w{BAR FOO,}}.  @xref{Transpose}, for
more on transposition.

@kindex M-@@
  To operate on words with an operation which acts on the region, use
the command @kbd{M-@@} (@code{mark-word}).  This command sets the mark
where @kbd{M-f} would move to.  @xref{Marking Objects}, for more
information about this command.

  The word commands' understanding of word boundaries is controlled by
the syntax table.  Any character can, for example, be declared to be a
word delimiter.  @xref{Syntax Tables,, Syntax Tables, elisp, The Emacs
Lisp Reference Manual}.

  In addition, see @ref{Position Info} for the @kbd{M-=}
(@code{count-words-region}) and @kbd{M-x count-words} commands, which
count and report the number of words in the region or buffer.

@node Sentences
@section Sentences
@cindex sentences
@cindex manipulating sentences

  The Emacs commands for manipulating sentences and paragraphs are
mostly on Meta keys, like the word-handling commands.

@table @kbd
@item M-a
Move back to the beginning of the sentence (@code{backward-sentence}).
@item M-e
Move forward to the end of the sentence (@code{forward-sentence}).
@item M-k
Kill forward to the end of the sentence (@code{kill-sentence}).
@item C-x @key{DEL}
Kill back to the beginning of the sentence (@code{backward-kill-sentence}).
@end table

@kindex M-a
@kindex M-e
@findex backward-sentence
@findex forward-sentence
  The commands @kbd{M-a} (@code{backward-sentence}) and @kbd{M-e}
(@code{forward-sentence}) move to the beginning and end of the current
sentence, respectively.  Their bindings were chosen to resemble
@kbd{C-a} and @kbd{C-e}, which move to the beginning and end of a
line.  Unlike them, @kbd{M-a} and @kbd{M-e} move over successive
sentences if repeated.

  Moving backward over a sentence places point just before the first
character of the sentence; moving forward places point right after the
punctuation that ends the sentence.  Neither one moves over the
whitespace at the sentence boundary.

@kindex M-k
@findex kill-sentence
  Just as @kbd{C-a} and @kbd{C-e} have a kill command, @kbd{C-k}, to
go with them, @kbd{M-a} and @kbd{M-e} have a corresponding kill
command: @kbd{M-k} (@code{kill-sentence}) kills from point to the end
of the sentence.  With a positive numeric argument @var{n}, it kills
the next @var{n} sentences; with a negative argument @minus{}@var{n},
it kills back to the beginning of the @var{n}th preceding sentence.

@kindex C-x DEL
@findex backward-kill-sentence
  The @kbd{C-x @key{DEL}} (@code{backward-kill-sentence}) kills back
to the beginning of a sentence.

  The sentence commands assume that you follow the American typist's
convention of putting two spaces at the end of a sentence.  That is, a
sentence ends wherever there is a @samp{.}, @samp{?} or @samp{!}
followed by the end of a line or two spaces, with any number of
@samp{)}, @samp{]}, @samp{'}, or @samp{"} characters allowed in
between.  A sentence also begins or ends wherever a paragraph begins
or ends.  It is useful to follow this convention, because it allows
the Emacs sentence commands to distinguish between periods that end a
sentence and periods that indicate abbreviations.

@vindex sentence-end-double-space
  If you want to use just one space between sentences, you can set the
variable @code{sentence-end-double-space} to @code{nil} to make the
sentence commands stop for single spaces.  However, this has a
drawback: there is no way to distinguish between periods that end
sentences and those that indicate abbreviations.  For convenient and
reliable editing, we therefore recommend you follow the two-space
convention.  The variable @code{sentence-end-double-space} also
affects filling (@pxref{Fill Commands}).

@vindex sentence-end
  The variable @code{sentence-end} controls how to recognize the end
of a sentence.  If non-@code{nil}, its value should be a regular
expression, which is used to match the last few characters of a
sentence, together with the whitespace following the sentence
(@pxref{Regexps}).  If the value is @code{nil}, the default, then
Emacs computes sentence ends according to various criteria such as the
value of @code{sentence-end-double-space}.

@vindex sentence-end-without-period
  Some languages, such as Thai, do not use periods to indicate the end
of a sentence.  Set the variable @code{sentence-end-without-period} to
@code{t} in such cases.

@node Paragraphs
@section Paragraphs
@cindex paragraphs
@cindex manipulating paragraphs

  The Emacs commands for manipulating paragraphs are also on Meta keys.

@table @kbd
@item M-@{
Move back to previous paragraph beginning (@code{backward-paragraph}).
@item M-@}
Move forward to next paragraph end (@code{forward-paragraph}).
@item M-h
Put point and mark around this or next paragraph (@code{mark-paragraph}).
@end table

@kindex M-@{
@kindex M-@}
@findex backward-paragraph
@findex forward-paragraph
  @kbd{M-@{} (@code{backward-paragraph}) moves to the beginning of the
current or previous paragraph, depending on where point is when the
command is invoked (see below for the definition of a paragraph).
@kbd{M-@}} (@code{forward-paragraph}) similarly moves to the end of
the current or next paragraph.  If there is a blank line before the
paragraph, @kbd{M-@{} moves to the blank line.

@kindex M-h
@findex mark-paragraph
  When you wish to operate on a paragraph, type @kbd{M-h}
(@code{mark-paragraph}) to set the region around it.  For example,
@kbd{M-h C-w} kills the paragraph around or after point.  @kbd{M-h}
puts point at the beginning and mark at the end of the paragraph point
was in.  If point is between paragraphs (in a run of blank lines, or
at a boundary), @kbd{M-h} sets the region around the paragraph
following point.  If there are blank lines preceding the first line of
the paragraph, one of these blank lines is included in the region.  If
the region is already active, the command sets the mark without
changing point, and each subsequent @kbd{M-h} further advances the
mark by one paragraph.

  The definition of a paragraph depends on the major mode.  In
Fundamental mode, as well as Text mode and related modes, a paragraph
is separated from neighboring paragraphs by one or more
@dfn{blank lines}---lines that are either empty, or consist solely of
space, tab and/or formfeed characters.  In programming language modes,
paragraphs are usually defined in a similar way, so that you can use
the paragraph commands even though there are no paragraphs as such in
a program.

  Note that an indented line is @emph{not} itself a paragraph break in
Text mode.  If you want indented lines to separate paragraphs, use
Paragraph-Indent Text mode instead.  @xref{Text Mode}.

  If you set a fill prefix, then paragraphs are delimited by all lines
which don't start with the fill prefix.  @xref{Filling}.

@vindex paragraph-start
@vindex paragraph-separate
  The precise definition of a paragraph boundary is controlled by the
variables @code{paragraph-separate} and @code{paragraph-start}.  The
value of @code{paragraph-start} is a regular expression that should
match lines that either start or separate paragraphs
(@pxref{Regexps}).  The value of @code{paragraph-separate} is another
regular expression that should match lines that separate paragraphs
without being part of any paragraph (for example, blank lines).  Lines
that start a new paragraph and are contained in it must match only
@code{paragraph-start}, not @code{paragraph-separate}.  For example,
in Fundamental mode, @code{paragraph-start} is @w{@code{"\f\\|[
\t]*$"}}, and @code{paragraph-separate} is @w{@code{"[ \t\f]*$"}}.

  Note that @code{paragraph-start} and @code{paragraph-separate} are
matched against the text at the left margin, which is not necessarily
the beginning of the line, so these regexps should not use @samp{^} as
an anchor, to ensure that the paragraph functions will work equally
within a region of text indented by a margin setting.

@node Pages
@section Pages

@cindex pages
@cindex formfeed character
  Within some text files, text is divided into @dfn{pages} delimited
by the @dfn{formfeed character} (@acronym{ASCII} code 12, also denoted
as @samp{control-L}), which is displayed in Emacs as the escape
sequence @samp{^L} (@pxref{Text Display}).  Traditionally, when such
text files are printed to hardcopy, each formfeed character forces a
page break.  Most Emacs commands treat it just like any other
character, so you can insert it with @kbd{C-q C-l}, delete it with
@key{DEL}, etc.  In addition, Emacs provides commands to move over
pages and operate on them.

@table @kbd
@item M-x what-page
Display the page number of point, and the line number within that page.
@item C-x [
Move point to previous page boundary (@code{backward-page}).
@item C-x ]
Move point to next page boundary (@code{forward-page}).
@item C-x C-p
Put point and mark around this page (or another page) (@code{mark-page}).
@item C-x l
Count the lines in this page (@code{count-lines-page}).
@end table

@findex what-page
  @kbd{M-x what-page} counts pages from the beginning of the file, and
counts lines within the page, showing both numbers in the echo area.

@kindex C-x [
@kindex C-x ]
@findex forward-page
@findex backward-page
  The @kbd{C-x [} (@code{backward-page}) command moves point to immediately
after the previous page delimiter.  If point is already right after a page
delimiter, it skips that one and stops at the previous one.  A numeric
argument serves as a repeat count.  The @kbd{C-x ]} (@code{forward-page})
command moves forward past the next page delimiter.

@kindex C-x C-p
@findex mark-page
  The @kbd{C-x C-p} command (@code{mark-page}) puts point at the
beginning of the current page (after that page delimiter at the
front), and the mark at the end of the page (after the page delimiter
at the end).

  @kbd{C-x C-p C-w} is a handy way to kill a page to move it
elsewhere.  If you move to another page delimiter with @kbd{C-x [} and
@kbd{C-x ]}, then yank the killed page, all the pages will be properly
delimited once again.  Making sure this works as expected is the
reason @kbd{C-x C-p} includes only the following page delimiter in the
region.

  A numeric argument to @kbd{C-x C-p} specifies which page to go to,
relative to the current one.  Zero means the current page, one means
the next page, and @minus{}1 means the previous one.

@kindex C-x l
@findex count-lines-page
  The @kbd{C-x l} command (@code{count-lines-page}) is good for deciding
where to break a page in two.  It displays in the echo area the total number
of lines in the current page, and then divides it up into those preceding
the current line and those following, as in

@example
Page has 96 (72+25) lines
@end example

@noindent
  Notice that the sum is off by one; this is correct if point is not at the
beginning of a line.

@vindex page-delimiter
  The variable @code{page-delimiter} controls where pages begin.  Its
value is a regular expression that matches the beginning of a line
that separates pages (@pxref{Regexps}).  The normal value of this
variable is @code{"^\f"}, which matches a formfeed character at the
beginning of a line.

@node Quotation Marks
@section Quotation Marks
@cindex Quotation marks
@cindex Electric Quote mode
@cindex mode, Electric Quote
@cindex curly quotes
@cindex curved quotes
@cindex guillemets
@findex electric-quote-mode

  One common way to quote is the typewriter convention, which quotes
using straight apostrophes @samp{'like this'} or double-quotes @samp{"like
this"}.  Another common way is the curved quote convention, which uses
left and right single or double quotation marks @t{‘like this’} or
@t{“like this”}@footnote{
The curved single quote characters are U+2018 @sc{left single quotation
mark} and U+2019 @sc{right single quotation mark}; the curved double quotes
are U+201C @sc{left double quotation mark} and U+201D @sc{right double
quotation mark}.  On text terminals which cannot display these
characters, the Info reader might show them as the typewriter ASCII
quote characters.
}.  In text files, typewriter quotes are simple and
portable; curved quotes are less ambiguous and typically look nicer.

@vindex electric-quote-chars
  Electric Quote mode makes it easier to type curved quotes.  As you
type characters it optionally converts @kbd{`} to @t{‘}, @kbd{'} to @t{’},
@kbd{``} to @t{“}, and @kbd{''} to @t{”}.  It's possible to change the
default quotes listed above, by customizing the variable
@code{electric-quote-chars}, a list of four characters, where the
items correspond to the left single quote, the right single quote, the
left double quote and the right double quote, respectively, whose
default value is @w{@code{'(@w{?}‘ ?’ ?“ ?”)}}.

@vindex electric-quote-paragraph
@vindex electric-quote-comment
@vindex electric-quote-string
  You can customize the behavior of Electric Quote mode by customizing
variables that control where it is active.  It is active in text
paragraphs if @code{electric-quote-paragraph} is non-@code{nil}, in
programming-language comments if @code{electric-quote-comment} is
non-@code{nil}, and in programming-language strings if
@code{electric-quote-string} is non-@code{nil}.  The default is
@code{nil} for @code{electric-quote-string} and @code{t} for the other
variables.

@vindex electric-quote-replace-double
  You can also set the option @code{electric-quote-replace-double} to
a non-@code{nil} value.  Then, typing @kbd{"} insert an appropriate
curved double quote depending on context: @t{“} at the beginning of
the buffer or after a line break, whitespace, opening parenthesis, or
quote character, and @t{”} otherwise.

  Electric Quote mode is disabled by default.  To toggle it in a
single buffer, use @kbd{M-x electric-quote-local-mode}.
To toggle it globally, type
@kbd{M-x electric-quote-mode}.  To suppress it for a single use,
type @kbd{C-q `} or @kbd{C-q '} instead of @kbd{`} or @kbd{'}.  To
insert a curved quote even when Electric Quote is disabled or
inactive, you can type @kbd{C-x 8 [} for @t{‘}, @kbd{C-x 8 ]} for
@t{’}, @kbd{C-x 8 @{} for @t{“}, and @kbd{C-x 8 @}} for @t{”}.
@xref{Inserting Text}.  Note that the value of
@code{electric-quote-chars} does not affect these keybindings, they
are not keybindings of @code{electric-quote-mode} but bound in
@code{global-map}.

@node Filling
@section Filling Text
@cindex filling text

  @dfn{Filling} text means breaking it up into lines that fit a
specified width.  Emacs does filling in two ways.  In Auto Fill mode,
inserting text with self-inserting characters also automatically fills
it.  There are also explicit fill commands that you can use when editing
text.

@menu
* Auto Fill::      Auto Fill mode breaks long lines automatically.
* Fill Commands::  Commands to refill paragraphs and center lines.
* Fill Prefix::    Filling paragraphs that are indented or in a comment, etc.
* Adaptive Fill::  How Emacs can determine the fill prefix automatically.
@end menu

@node Auto Fill
@subsection Auto Fill Mode
@cindex Auto Fill mode
@cindex mode, Auto Fill

  @dfn{Auto Fill} mode is a buffer-local minor mode (@pxref{Minor
Modes}) in which lines are broken automatically when the line becomes
too wide and you type @kbd{@key{SPC}} or @kbd{@key{RET}}.

@table @kbd
@item M-x auto-fill-mode
Enable or disable Auto Fill mode.
@item @key{SPC}
@itemx @key{RET}
In Auto Fill mode, break lines when appropriate.
@end table

@findex auto-fill-mode
  The mode command @kbd{M-x auto-fill-mode} toggles Auto Fill mode in
the current buffer.  Like any other minor mode, with a positive
numeric argument, it enables Auto Fill mode, and with a negative
argument it disables it.  To enable Auto Fill mode automatically in
certain major modes, add @code{auto-fill-mode} to the mode hooks
(@pxref{Major Modes}).  When Auto Fill mode is enabled, the mode
indicator @samp{Fill} appears in the mode line (@pxref{Mode Line}).

  Auto Fill mode breaks lines automatically at the appropriate places
whenever lines get longer than the desired width.  This line breaking
occurs only when you type @kbd{@key{SPC}} or @kbd{@key{RET}}.  If you
wish to insert a space or newline without permitting line-breaking,
type @kbd{C-q @key{SPC}} or @kbd{C-q C-j} respectively.  Also,
@kbd{C-o} inserts a newline without line breaking.

@cindex kinsoku line-breaking rules
  The place where Auto Fill breaks a line depends on the line's
characters.  For characters from @acronym{ASCII}, Latin, and most
other scripts Emacs breaks a line on space characters, to keep the
words intact.  But for CJK scripts, a line can be broken between any
two characters.  (If you load the @file{kinsoku} library, Emacs will
avoid breaking a line between certain pairs of CJK characters, where
special rules prohibit that.)

  When Auto Fill mode breaks a line, it tries to obey the
@dfn{adaptive fill prefix}: if a fill prefix can be deduced from the
first and/or second line of the current paragraph, it is inserted into
the new line (@pxref{Adaptive Fill}).  Otherwise the new line is
indented, as though you had typed @key{TAB} on it
(@pxref{Indentation}).  In a programming language mode, if a line is
broken in the middle of a comment, the comment is split by inserting
new comment delimiters as appropriate.

  Auto Fill mode does not refill entire paragraphs; it breaks lines
but does not merge lines.  Therefore, editing in the middle of a
paragraph can result in a paragraph that is not correctly filled.  To
fill it, call the explicit fill commands
@iftex
described in the next section.
@end iftex
@ifnottex
(@pxref{Fill Commands}).
@end ifnottex

  A similar feature that wraps long lines automatically at display
time is Visual Line Mode (@pxref{Visual Line Mode}).

@node Fill Commands
@subsection Explicit Fill Commands

@table @kbd
@item M-q
Fill current paragraph (@code{fill-paragraph}).
@item C-x f
Set the fill column (@code{set-fill-column}).
@item M-x fill-region
Fill each paragraph in the region (@code{fill-region}).
@item M-x fill-region-as-paragraph
Fill the region, considering it as one paragraph.
@item M-x center-line
Center a line.
@end table

@kindex M-q
@findex fill-paragraph
  The command @kbd{M-q} (@code{fill-paragraph}) @dfn{fills} the
current paragraph.  It redistributes the line breaks within the
paragraph, and deletes any excess space and tab characters occurring
within the paragraph, in such a way that the lines end up fitting
within a certain maximum width.  Like Auto Fill mode, this and other
filling commands usually break lines at space characters, but for CJK
characters these commands can break a line between almost any two
characters, and they can also obey the kinsoku rules.  @xref{Auto
Fill}.

@findex fill-region
  Normally, @kbd{M-q} acts on the paragraph where point is, but if
point is between paragraphs, it acts on the paragraph after point.  If
the region is active, it acts instead on the text in the region.  You
can also call @kbd{M-x fill-region} to specifically fill the text in
the region.

@findex fill-region-as-paragraph
  @kbd{M-q} and @code{fill-region} use the usual Emacs criteria for
finding paragraph boundaries (@pxref{Paragraphs}).  For more control,
you can use @kbd{M-x fill-region-as-paragraph}, which refills
everything between point and mark as a single paragraph.  This command
deletes any blank lines within the region, so separate blocks of text
end up combined into one block.

@cindex justification
  A numeric argument to @kbd{M-q} tells it to @dfn{justify} the text
as well as filling it.  This means that extra spaces are inserted to
make the right margin line up exactly at the fill column.  To remove
the extra spaces, use @kbd{M-q} with no argument.  (Likewise for
@code{fill-region}.)

@vindex fill-column
@kindex C-x f
@findex set-fill-column
  The maximum line width for filling is specified by the buffer-local
variable @code{fill-column}.  The default value (@pxref{Locals}) is
70.  The easiest way to set @code{fill-column} in the current buffer
is to use the command @kbd{C-x f} (@code{set-fill-column}).  With a
numeric argument, it uses that as the new fill column.  With just
@kbd{C-u} as argument, it sets @code{fill-column} to the current
horizontal position of point.

@cindex centering
@findex center-line
  The command @kbd{M-x center-line} centers the current line
within the current fill column.  With an argument @var{n}, it centers
@var{n} lines individually and moves past them.  This binding is
made by Text mode and is available only in that and related modes
(@pxref{Text Mode}).

  By default, Emacs considers a period followed by two spaces or by a
newline as the end of a sentence; a period followed by just one space
indicates an abbreviation, not the end of a sentence.  Accordingly,
the fill commands will not break a line after a period followed by
just one space.  If you set the variable
@code{sentence-end-double-space} to @code{nil}, the fill commands will
break a line after a period followed by one space, and put just one
space after each period.  @xref{Sentences}, for other effects and
possible drawbacks of this.

@vindex colon-double-space
  If the variable @code{colon-double-space} is non-@code{nil}, the
fill commands put two spaces after a colon.

@vindex fill-nobreak-predicate
  To specify additional conditions where line-breaking is not allowed,
customize the abnormal hook variable @code{fill-nobreak-predicate}
(@pxref{Hooks}).  Each function in this hook is called with no
arguments, with point positioned where Emacs is considering breaking a
line.  If a function returns a non-@code{nil} value, Emacs will not
break the line there.  Functions you can use there include:
@code{fill-single-word-nobreak-p} (don't break after the first word of
a sentence or before the last); @code{fill-single-char-nobreak-p}
(don't break after a one-letter word preceded by a whitespace
character); @code{fill-french-nobreak-p} (don't break after @samp{(}
or before @samp{)}, @samp{:} or @samp{?}); and
@code{fill-polish-nobreak-p} (don't break after a one letter word,
even if preceded by a non-whitespace character).

  Emacs can display an indicator in the @code{fill-column} position
using the Display fill column indicator mode (@pxref{Displaying
Boundaries, display-fill-column-indicator}).

@node Fill Prefix
@subsection The Fill Prefix

@cindex fill prefix
  The @dfn{fill prefix} feature allows paragraphs to be filled so that
each line starts with a special string of characters (such as a
sequence of spaces, giving an indented paragraph).  You can specify a
fill prefix explicitly; otherwise, Emacs tries to deduce one
automatically (@pxref{Adaptive Fill}).

@table @kbd
@item C-x .
Set the fill prefix (@code{set-fill-prefix}).
@item M-q
Fill a paragraph using current fill prefix (@code{fill-paragraph}).
@item M-x fill-individual-paragraphs
Fill the region, considering each change of indentation as starting a
new paragraph.
@item M-x fill-nonuniform-paragraphs
Fill the region, considering only paragraph-separator lines as starting
a new paragraph.
@end table

@kindex C-x .
@findex set-fill-prefix
  To specify a fill prefix for the current buffer, move to a line that
starts with the desired prefix, put point at the end of the prefix,
and type @w{@kbd{C-x .}}@: (@code{set-fill-prefix}).  (That's a period
after the @kbd{C-x}.)  To turn off the fill prefix, specify an empty
prefix: type @w{@kbd{C-x .}}@: with point at the beginning of a line.

  When a fill prefix is in effect, the fill commands remove the fill
prefix from each line of the paragraph before filling, and insert it
on each line after filling.  (The beginning of the first line of the
paragraph is left unchanged, since often that is intentionally
different.)  Auto Fill mode also inserts the fill prefix automatically
when it makes a new line (@pxref{Auto Fill}).  The @kbd{C-o} command
inserts the fill prefix on new lines it creates, when you use it at
the beginning of a line (@pxref{Blank Lines}).  Conversely, the
command @kbd{M-^} deletes the prefix (if it occurs) after the newline
that it deletes (@pxref{Indentation}).

  For example, if @code{fill-column} is 40 and you set the fill prefix
to @samp{;; }, then @kbd{M-q} in the following text

@example
;; This is an
;; example of a paragraph
;; inside a Lisp-style comment.
@end example

@noindent
produces this:

@example
;; This is an example of a paragraph
;; inside a Lisp-style comment.
@end example

  Lines that do not start with the fill prefix are considered to start
paragraphs, both in @kbd{M-q} and the paragraph commands; this gives
good results for paragraphs with hanging indentation (every line
indented except the first one).  Lines which are blank or indented once
the prefix is removed also separate or start paragraphs; this is what
you want if you are writing multi-paragraph comments with a comment
delimiter on each line.

@findex fill-individual-paragraphs
  You can use @kbd{M-x fill-individual-paragraphs} to set the fill
prefix for each paragraph automatically.  This command divides the
region into paragraphs, treating every change in the amount of
indentation as the start of a new paragraph, and fills each of these
paragraphs.  Thus, all the lines in one paragraph have the same
amount of indentation.  That indentation serves as the fill prefix for
that paragraph.

@findex fill-nonuniform-paragraphs
  @kbd{M-x fill-nonuniform-paragraphs} is a similar command that divides
the region into paragraphs in a different way.  It considers only
paragraph-separating lines (as defined by @code{paragraph-separate}) as
starting a new paragraph.  Since this means that the lines of one
paragraph may have different amounts of indentation, the fill prefix
used is the smallest amount of indentation of any of the lines of the
paragraph.  This gives good results with styles that indent a paragraph's
first line more or less that the rest of the paragraph.

@vindex fill-prefix
  The fill prefix is stored in the variable @code{fill-prefix}.  Its value
is a string, or @code{nil} when there is no fill prefix.  This is a
per-buffer variable; altering the variable affects only the current buffer,
but there is a default value which you can change as well.  @xref{Locals}.

  The @code{indentation} text property provides another way to control
the amount of indentation paragraphs receive.  @xref{Enriched
Indentation}.

@node Adaptive Fill
@subsection Adaptive Filling

@cindex adaptive filling
  The fill commands can deduce the proper fill prefix for a paragraph
automatically in certain cases: either whitespace or certain punctuation
characters at the beginning of a line are propagated to all lines of the
paragraph.

  If the paragraph has two or more lines, the fill prefix is taken from
the paragraph's second line, but only if it appears on the first line as
well.

  If a paragraph has just one line, fill commands @emph{may} take a
prefix from that line.  The decision is complicated because there are
three reasonable things to do in such a case:

@itemize @bullet
@item
Use the first line's prefix on all the lines of the paragraph.

@item
Indent subsequent lines with whitespace, so that they line up under the
text that follows the prefix on the first line, but don't actually copy
the prefix from the first line.

@item
Don't do anything special with the second and following lines.
@end itemize

  All three of these styles of formatting are commonly used.  So the
fill commands try to determine what you would like, based on the prefix
that appears and on the major mode.  Here is how.

@vindex adaptive-fill-first-line-regexp
  If the prefix found on the first line matches
@code{adaptive-fill-first-line-regexp}, or if it appears to be a
comment-starting sequence (this depends on the major mode), then the
prefix found is used for filling the paragraph, provided it would not
act as a paragraph starter on subsequent lines.

  Otherwise, the prefix found is converted to an equivalent number of
spaces, and those spaces are used as the fill prefix for the rest of the
lines, provided they would not act as a paragraph starter on subsequent
lines.

  In Text mode, and other modes where only blank lines and page
delimiters separate paragraphs, the prefix chosen by adaptive filling
never acts as a paragraph starter, so it can always be used for filling.

@vindex adaptive-fill-mode
@vindex adaptive-fill-regexp
  The variable @code{adaptive-fill-regexp} determines what kinds of line
beginnings can serve as a fill prefix: any characters at the start of
the line that match this regular expression are used.  If you set the
variable @code{adaptive-fill-mode} to @code{nil}, the fill prefix is
never chosen automatically.

@vindex adaptive-fill-function
  You can specify more complex ways of choosing a fill prefix
automatically by setting the variable @code{adaptive-fill-function} to a
function.  This function is called with point after the left margin of a
line, and it should return the appropriate fill prefix based on that
line.  If it returns @code{nil}, @code{adaptive-fill-regexp} gets
a chance to find a prefix.

@node Case
@section Case Conversion Commands
@cindex case conversion

  Emacs has commands for converting either a single word or any arbitrary
range of text to upper case or to lower case.

@table @kbd
@item M-l
Convert following word to lower case (@code{downcase-word}).
@item M-u
Convert following word to upper case (@code{upcase-word}).
@item M-c
Capitalize the following word (@code{capitalize-word}).
@item C-x C-l
Convert region to lower case (@code{downcase-region}).
@item C-x C-u
Convert region to upper case (@code{upcase-region}).
@end table

@kindex M-l
@kindex M-u
@kindex M-c
@cindex words, case conversion
@cindex converting text to upper or lower case
@cindex capitalizing words
@findex downcase-word
@findex upcase-word
@findex capitalize-word
  @kbd{M-l} (@code{downcase-word}) converts the word after point to
lower case, moving past it.  Thus, repeating @kbd{M-l} converts
successive words.  @kbd{M-u} (@code{upcase-word}) converts to all
capitals instead, while @kbd{M-c} (@code{capitalize-word}) puts the
first letter of the word into upper case and the rest into lower case.
All these commands convert several words at once if given an argument.
They are especially convenient for converting a large amount of text
from all upper case to mixed case, because you can move through the
text using @kbd{M-l}, @kbd{M-u} or @kbd{M-c} on each word as
appropriate, occasionally using @kbd{M-f} instead to skip a word.

  When given a negative argument, the word case conversion commands apply
to the appropriate number of words before point, but do not move point.
This is convenient when you have just typed a word in the wrong case: you
can give the case conversion command and continue typing.

  If a word case conversion command is given in the middle of a word,
it applies only to the part of the word which follows point.  (This is
comparable to what @kbd{M-d} (@code{kill-word}) does.)  With a
negative argument, case conversion applies only to the part of the
word before point.

@kindex C-x C-l
@kindex C-x C-u
@findex downcase-region
@findex upcase-region
  The other case conversion commands are @kbd{C-x C-u}
(@code{upcase-region}) and @kbd{C-x C-l} (@code{downcase-region}), which
convert everything between point and mark to the specified case.  Point and
mark do not move.

  The region case conversion commands @code{upcase-region} and
@code{downcase-region} are normally disabled.  This means that they ask
for confirmation if you try to use them.  When you confirm, you may
enable the command, which means it will not ask for confirmation again.
@xref{Disabling}.

@node Text Mode
@section Text Mode
@cindex Text mode
@cindex mode, Text
@findex text-mode

  Text mode is a major mode for editing files of text in a human
language.  Files which have names ending in the extension @file{.txt}
are usually opened in Text mode (@pxref{Choosing Modes}).  To
explicitly switch to Text mode, type @kbd{M-x text-mode}.

  In Text mode, only blank lines and page delimiters separate
paragraphs.  As a result, paragraphs can be indented, and adaptive
filling determines what indentation to use when filling a paragraph.
@xref{Adaptive Fill}.

@kindex TAB @r{(Text mode)}
  In Text mode, the @key{TAB} (@code{indent-for-tab-command}) command
usually inserts whitespace up to the next tab stop, instead of
indenting the current line.  @xref{Indentation}, for details.

  Text mode turns off the features concerned with comments except when
you explicitly invoke them.  It changes the syntax table so that
apostrophes are considered part of words (e.g., @samp{don't} is
considered one word).  However, if a word starts with an apostrophe,
it is treated as a prefix for the purposes of capitalization
(e.g., @kbd{M-c} converts @samp{'hello'} into @samp{'Hello'}, as
expected).

@cindex Paragraph-Indent Text mode
@cindex mode, Paragraph-Indent Text
@findex paragraph-indent-text-mode
@findex paragraph-indent-minor-mode
  If you indent the first lines of paragraphs, then you should use
Paragraph-Indent Text mode (@kbd{M-x paragraph-indent-text-mode})
rather than Text mode.  In that mode, you do not need to have blank
lines between paragraphs, because the first-line indentation is
sufficient to start a paragraph; however paragraphs in which every
line is indented are not supported.  Use @kbd{M-x
paragraph-indent-minor-mode} to enable an equivalent minor mode for
situations where you shouldn't change the major mode---in mail
composition, for instance.

@kindex M-TAB @r{(Text mode)}
  Text mode binds @kbd{M-@key{TAB}} to @code{ispell-complete-word}.
This command performs completion of the partial word in the buffer
before point, using the spelling dictionary as the space of possible
words.  @xref{Spelling}.  If your window manager defines
@kbd{M-@key{TAB}} to switch windows, you can type @kbd{@key{ESC}
@key{TAB}} or @kbd{C-M-i} instead.

@vindex text-mode-hook
  Entering Text mode runs the mode hook @code{text-mode-hook}
(@pxref{Major Modes}).

  The following sections describe several major modes that are
@dfn{derived} from Text mode.  These derivatives share most of the
features of Text mode described above.  In particular, derivatives of
Text mode run @code{text-mode-hook} prior to running their own mode
hooks.

@node Outline Mode
@section Outline Mode
@cindex Outline mode
@cindex mode, Outline
@cindex invisible lines

@findex outline-mode
@findex outline-minor-mode
@vindex outline-minor-mode-prefix
@vindex outline-mode-hook
  Outline mode is a major mode derived from Text mode, which is
specialized for editing outlines.  It provides commands to navigate
between entries in the outline structure, and commands to make parts
of a buffer temporarily invisible, so that the outline structure may
be more easily viewed.  Type @kbd{M-x outline-mode} to switch to
Outline mode.  Entering Outline mode runs the hook
@code{text-mode-hook} followed by the hook @code{outline-mode-hook}
(@pxref{Hooks}).

  When you use an Outline mode command to make a line invisible
(@pxref{Outline Visibility}), the line disappears from the screen.  An
ellipsis (three periods in a row) is displayed at the end of the
previous visible line, to indicate the hidden text.  Multiple
consecutive invisible lines produce just one ellipsis.

  Editing commands that operate on lines, such as @kbd{C-n} and
@kbd{C-p}, treat the text of the invisible line as part of the
previous visible line.  Killing the ellipsis at the end of a visible
line really kills all the following invisible text associated with the
ellipsis.

  Outline minor mode is a buffer-local minor mode which provides the
same commands as the major mode, Outline mode, but can be used in
conjunction with other major modes.  You can type @kbd{M-x
outline-minor-mode} to toggle Outline minor mode in the current
buffer, or use a file-local variable setting to enable it in a
specific file (@pxref{File Variables}).

@kindex C-c @@ @r{(Outline minor mode)}
  The major mode, Outline mode, provides special key bindings on the
@kbd{C-c} prefix.  Outline minor mode provides similar bindings with
@kbd{C-c @@} as the prefix; this is to reduce the conflicts with the
major mode's special commands.  (The variable
@code{outline-minor-mode-prefix} controls the prefix used.)

@vindex outline-minor-mode-cycle
  If the @code{outline-minor-mode-cycle} user option is
non-@code{nil}, the @kbd{TAB} and @kbd{S-TAB} keys are enabled on the
outline heading lines.  @kbd{TAB} cycles hiding, showing the
sub-heading, and showing all for the current section.  @kbd{S-TAB}
does the same for the entire buffer.

@menu
* Outline Format::      What the text of an outline looks like.
* Outline Motion::      Special commands for moving through outlines.
* Outline Visibility::  Commands to control what is visible.
* Outline Views::       Outlines and multiple views.
* Foldout::             Folding means zooming in on outlines.
@end menu

@node Outline Format
@subsection Format of Outlines

@cindex heading lines (Outline mode)
@cindex body lines (Outline mode)
  Outline mode assumes that the lines in the buffer are of two types:
@dfn{heading lines} and @dfn{body lines}.  A heading line represents a
topic in the outline.  Heading lines start with one or more asterisk
(@samp{*}) characters; the number of asterisks determines the depth of
the heading in the outline structure.  Thus, a heading line with one
@samp{*} is a major topic; all the heading lines with two @samp{*}s
between it and the next one-@samp{*} heading are its subtopics; and so
on.  Any line that is not a heading line is a body line.  Body lines
belong with the preceding heading line.  Here is an example:

@example
* Food
This is the body,
which says something about the topic of food.

** Delicious Food
This is the body of the second-level header.

** Distasteful Food
This could have
a body too, with
several lines.

*** Dormitory Food

* Shelter
Another first-level topic with its header line.
@end example

  A heading line together with all following body lines is called
collectively an @dfn{entry}.  A heading line together with all following
deeper heading lines and their body lines is called a @dfn{subtree}.

@vindex outline-regexp
  You can customize the criterion for distinguishing heading lines by
setting the variable @code{outline-regexp}.  (The recommended ways to
do this are in a major mode function or with a file local variable.)
Any line whose beginning has a match for this regexp is considered a
heading line.  Matches that start within a line (not at the left
margin) do not count.

  The length of the matching text determines the level of the heading;
longer matches make a more deeply nested level.  Thus, for example, if
a text formatter has commands @samp{@@chapter}, @samp{@@section} and
@samp{@@subsection} to divide the document into chapters and sections,
you could make those lines count as heading lines by setting
@code{outline-regexp} to @samp{"@@chap\\|@@\\(sub\\)*section"}.  Note
the trick: the two words @samp{chapter} and @samp{section} are equally
long, but by defining the regexp to match only @samp{chap} we ensure
that the length of the text matched on a chapter heading is shorter,
so that Outline mode will know that sections are contained in
chapters.  This works as long as no other command starts with
@samp{@@chap}.

@vindex outline-level
  You can explicitly specify a rule for calculating the level of a
heading line by setting the variable @code{outline-level}.  The value
of @code{outline-level} should be a function that takes no arguments
and returns the level of the current heading.  The recommended ways to
set this variable are in a major mode command or with a file local
variable.

@node Outline Motion
@subsection Outline Motion Commands

  Outline mode provides special motion commands that move backward and
forward to heading lines.

@table @kbd
@item C-c C-n
@findex outline-next-visible-heading
@kindex C-c C-n @r{(Outline mode)}
Move point to the next visible heading line
(@code{outline-next-visible-heading}).
@item C-c C-p
@findex outline-previous-visible-heading
@kindex C-c C-p @r{(Outline mode)}
Move point to the previous visible heading line
(@code{outline-previous-visible-heading}).
@item C-c C-f
@findex outline-forward-same-level
@kindex C-c C-f @r{(Outline mode)}
Move point to the next visible heading line at the same level
as the one point is on (@code{outline-forward-same-level}).
@item C-c C-b
@findex outline-backward-same-level
@kindex C-c C-b @r{(Outline mode)}
Move point to the previous visible heading line at the same level
(@code{outline-backward-same-level}).
@item C-c C-u
@findex outline-up-heading
@kindex C-c C-u @r{(Outline mode)}
Move point up to a lower-level (more inclusive) visible heading line
(@code{outline-up-heading}).
@end table

  All of the above commands accept numeric arguments as repeat counts.
For example, @kbd{C-c C-f}, when given an argument, moves forward that
many visible heading lines on the same level, and @kbd{C-c C-u} with
an argument moves out of that many nested levels.

@node Outline Visibility
@subsection Outline Visibility Commands

  Outline mode provides several commands for temporarily hiding or
revealing parts of the buffer, based on the outline structure.  These
commands are not undoable; their effects are simply not recorded by
the undo mechanism, so you can undo right past them (@pxref{Undo}).

  Many of these commands act on the current heading line.  If
point is on a heading line, that is the current heading line; if point
is on a body line, the current heading line is the nearest preceding
header line.

@table @kbd
@item C-c C-c
Make the current heading line's body invisible
(@code{outline-hide-entry}).
@item C-c C-e
Make the current heading line's body visible
(@code{outline-show-entry}).
@item C-c C-d
Make everything under the current heading invisible, not including the
heading itself (@code{outline-hide-subtree}).
@item C-c C-s
Make everything under the current heading visible, including body,
subheadings, and their bodies (@code{outline-show-subtree}).
@item C-c C-l
Make the body of the current heading line, and of all its subheadings,
invisible (@code{outline-hide-leaves}).
@item C-c C-k
Make all subheadings of the current heading line, at all levels,
visible (@code{outline-show-branches}).
@item C-c C-i
Make immediate subheadings (one level down) of the current heading
line visible (@code{outline-show-children}).
@item C-c C-t
Make all body lines in the buffer invisible
(@code{outline-hide-body}).
@item C-c C-a
Make all lines in the buffer visible (@code{outline-show-all}).
@item C-c C-q
Hide everything except the top @var{n} levels of heading lines
(@code{outline-hide-sublevels}).
@item C-c C-o
Hide everything except for the heading or body that point is in, plus
the headings leading up from there to the top level of the outline
(@code{outline-hide-other}).
@end table

@findex outline-hide-entry
@findex outline-show-entry
@kindex C-c C-c @r{(Outline mode)}
@kindex C-c C-e @r{(Outline mode)}
  The simplest of these commands are @kbd{C-c C-c}
(@code{outline-hide-entry}), which hides the body lines directly
following the current heading line, and @kbd{C-c C-e}
(@code{outline-show-entry}), which reveals them.  Subheadings and
their bodies are not affected.

@findex outline-hide-subtree
@findex outline-show-subtree
@kindex C-c C-s @r{(Outline mode)}
@kindex C-c C-d @r{(Outline mode)}
@cindex subtree (Outline mode)
  The commands @kbd{C-c C-d} (@code{outline-hide-subtree}) and
@kbd{C-c C-s} (@code{outline-show-subtree}) are more powerful.  They
apply to the current heading line's @dfn{subtree}: its body, all of
its subheadings, both direct and indirect, and all of their bodies.

@findex outline-hide-leaves
@findex outline-show-branches
@findex outline-show-children
@kindex C-c C-l @r{(Outline mode)}
@kindex C-c C-k @r{(Outline mode)}
@kindex C-c C-i @r{(Outline mode)}
  The command @kbd{C-c C-l} (@code{outline-hide-leaves}) hides the
body of the current heading line as well as all the bodies in its
subtree; the subheadings themselves are left visible.  The command
@kbd{C-c C-k} (@code{outline-show-branches}) reveals the subheadings,
if they had previously been hidden (e.g., by @kbd{C-c C-d}).  The
command @kbd{C-c C-i} (@code{outline-show-children}) is a weaker
version of this; it reveals just the direct subheadings, i.e., those
one level down.

@findex outline-hide-other
@kindex C-c C-o @r{(Outline mode)}
  The command @kbd{C-c C-o} (@code{outline-hide-other}) hides
everything except the entry that point is in, plus its parents (the
headers leading up from there to top level in the outline) and the top
level headings.  It also reveals body lines preceding the first
heading in the buffer.

@findex outline-hide-body
@findex outline-show-all
@kindex C-c C-t @r{(Outline mode)}
@kindex C-c C-a @r{(Outline mode)}
@findex hide-sublevels
@kindex C-c C-q @r{(Outline mode)}
  The remaining commands affect the whole buffer.  @kbd{C-c C-t}
(@code{outline-hide-body}) makes all body lines invisible, so that you
see just the outline structure (as a special exception, it will not
hide lines at the top of the file, preceding the first header line,
even though these are technically body lines).  @kbd{C-c C-a}
(@code{outline-show-all}) makes all lines visible.  @kbd{C-c C-q}
(@code{outline-hide-sublevels}) hides all but the top level headings
at and above the level of the current heading line (defaulting to 1 if
point is not on a heading); with a numeric argument @var{n}, it hides
everything except the top @var{n} levels of heading lines.  Note that
it completely reveals all the @var{n} top levels and the body lines
before the first heading.

@cindex cycle visibility, in Outline mode
@findex outline-cycle
@findex outline-cycle-buffer
  Outline also provides two convenience commands to cycle the
visibility of each section and the whole buffer.  Typing
@kbd{@key{TAB}} (@code{outline-cycle}) on a heading cycles the current
section between ``hide all'', ``subheadings'', and ``show all''
states.  Typing @kbd{S-@key{TAB}} (@code{outline-cycle-buffer}) cycles
the whole buffer between ``only top-level headings'', ``all headings
and subheadings'', and ``show all'' states.

@anchor{Outline Search}
@findex reveal-mode
@vindex search-invisible
  When incremental search finds text that is hidden by Outline mode,
it makes that part of the buffer visible.  If you exit the search at
that position, the text remains visible.  To toggle whether or not
an active incremental search can match hidden text, type @kbd{M-s i}.
To change the default for future searches, customize the option
@code{search-invisible}.  (This option also affects how @code{query-replace}
and related functions treat hidden text, @pxref{Query Replace}.)
You can also automatically make text visible as you navigate in it by
using Reveal mode (@kbd{M-x reveal-mode}), a buffer-local minor mode.

@node Outline Views
@subsection Viewing One Outline in Multiple Views

@cindex multiple views of outline
@cindex views of an outline
@cindex outline with multiple views
@cindex indirect buffers and outlines
  You can display two views of a single outline at the same time, in
different windows.  To do this, you must create an indirect buffer using
@kbd{M-x make-indirect-buffer}.  The first argument of this command is
the existing outline buffer name, and its second argument is the name to
use for the new indirect buffer.  @xref{Indirect Buffers}.

  Once the indirect buffer exists, you can display it in a window in the
normal fashion, with @kbd{C-x 4 b} or other Emacs commands.  The Outline
mode commands to show and hide parts of the text operate on each buffer
independently; as a result, each buffer can have its own view.  If you
want more than two views on the same outline, create additional indirect
buffers.

@node Foldout
@subsection Folding Editing

@cindex folding editing
  The Foldout package extends Outline mode and Outline minor mode with
folding commands.  The idea of folding is that you zoom in on a
nested portion of the outline, while hiding its relatives at higher
levels.

  Consider an Outline mode buffer with all the text and subheadings under
level-1 headings hidden.  To look at what is hidden under one of these
headings, you could use @kbd{C-c C-e} (@kbd{M-x outline-show-entry})
to expose the body, or @kbd{C-c C-i} to expose the child (level-2)
headings.

@kindex C-c C-z
@findex foldout-zoom-subtree
  With Foldout, you use @kbd{C-c C-z} (@kbd{M-x foldout-zoom-subtree}).
This exposes the body and child subheadings, and narrows the buffer so
that only the @w{level-1} heading, the body and the level-2 headings are
visible.  Now to look under one of the level-2 headings, position the
cursor on it and use @kbd{C-c C-z} again.  This exposes the level-2 body
and its level-3 child subheadings and narrows the buffer again.  Zooming
in on successive subheadings can be done as much as you like.  A string
in the mode line shows how deep you've gone.

  When zooming in on a heading, to see only the child subheadings specify
a numeric argument: @kbd{C-u C-c C-z}.  The number of levels of children
can be specified too (compare @kbd{M-x outline-show-children}), e.g.,
@w{@kbd{M-2 C-c C-z}} exposes two levels of child subheadings.
Alternatively, the body can be specified with a negative argument:
@w{@kbd{M-- C-c C-z}}.  The whole subtree can be expanded, similarly to
@kbd{C-c C-s} (@kbd{M-x outline-show-subtree}), by specifying a zero
argument: @w{@kbd{M-0 C-c C-z}}.

  While you're zoomed in, you can still use Outline mode's exposure and
hiding functions without disturbing Foldout.  Also, since the buffer is
narrowed, global editing actions will only affect text under the
zoomed-in heading.  This is useful for restricting changes to a
particular chapter or section of your document.

@kindex C-c C-x
@findex foldout-exit-fold
  To unzoom (exit) a fold, use @kbd{C-c C-x} (@kbd{M-x foldout-exit-fold}).
This hides all the text and subheadings under the top-level heading and
returns you to the previous view of the buffer.  Specifying a numeric
argument exits that many levels of folds.  Specifying a zero argument
exits all folds.

  To cancel the narrowing of a fold without hiding the text and
subheadings, specify a negative argument.  For example, @w{@kbd{M--2 C-c
C-x}} exits two folds and leaves the text and subheadings exposed.

  Foldout mode also provides mouse commands for entering and exiting
folds, and for showing and hiding text:

@table @asis
@item @kbd{C-M-mouse-1} zooms in on the heading clicked on
@itemize @w{}
@item
single click: expose body.
@item
double click: expose subheadings.
@item
triple click: expose body and subheadings.
@item
quad click: expose entire subtree.
@end itemize
@item @kbd{C-M-mouse-2} exposes text under the heading clicked on
@itemize @w{}
@item
single click: expose body.
@item
double click: expose subheadings.
@item
triple click: expose body and subheadings.
@item
quad click: expose entire subtree.
@end itemize
@item @kbd{C-M-mouse-3} hides text under the heading clicked on or exits fold
@itemize @w{}
@item
single click: hide subtree.
@item
double click: exit fold and hide text.
@item
triple click: exit fold without hiding text.
@item
quad click: exit all folds and hide text.
@end itemize
@end table

@c FIXME not marked as a user variable
@vindex foldout-mouse-modifiers
  You can specify different modifier keys (instead of
@kbd{@key{Ctrl}-@key{Meta}-}) by setting @code{foldout-mouse-modifiers}; but if
you have already loaded the @file{foldout.el} library, you must reload
it in order for this to take effect.

  To use the Foldout package, you can type @kbd{M-x load-library
@key{RET} foldout @key{RET}}; or you can arrange for to do that
automatically by putting the following in your init file:

@example
(with-eval-after-load "outline"
  (require 'foldout))
@end example

@node Org Mode
@section Org Mode
@cindex organizer
@cindex planner
@cindex Org mode
@cindex mode, Org

@findex org-mode
  Org mode is a variant of Outline mode for using Emacs as an
organizer and/or authoring system.  Files with names ending in the
extension @file{.org} are opened in Org mode (@pxref{Choosing Modes}).
To explicitly switch to Org mode, type @kbd{M-x org-mode}.

  In Org mode, as in Outline mode, each entry has a heading line that
starts with one or more @samp{*} characters.  @xref{Outline Format}.
In addition, any line that begins with the @samp{#} character is
treated as a comment.

@kindex TAB @r{(Org Mode)}
@findex org-cycle
  Org mode provides commands for easily viewing and manipulating the
outline structure.  The simplest of these commands is @key{TAB}
(@code{org-cycle}).  If invoked on a heading line, it cycles through
the different visibility states of the subtree: (i) showing only that
heading line, (ii) showing only the heading line and the heading lines
of its direct children, if any, and (iii) showing the entire subtree.
If invoked in a body line, the global binding for @key{TAB} is
executed.

@kindex S-TAB @r{(Org Mode)}
@findex org-shifttab
  Typing @kbd{S-@key{TAB}} (@code{org-shifttab}) anywhere in an Org mode
buffer cycles the visibility of the entire outline structure, between
(i) showing only top-level heading lines, (ii) showing all heading
lines but no body lines, and (iii) showing everything.

@kindex M-UP @r{(Org Mode)}
@kindex M-DOWN @r{(Org Mode)}
@kindex M-LEFT @r{(Org Mode)}
@kindex M-RIGHT @r{(Org Mode)}
@findex org-metaup
@findex org-metadown
@findex org-metaleft
@findex org-metaright
  You can move an entire entry up or down in the buffer, including its
body lines and subtree (if any), by typing @kbd{M-@key{UP}}
(@code{org-metaup}) or @kbd{M-@key{DOWN}} (@code{org-metadown}) on the
heading line.  Similarly, you can promote or demote a heading line
with @kbd{M-@key{LEFT}} (@code{org-metaleft}) and @kbd{M-@key{RIGHT}}
(@code{org-metaright}).  These commands execute their global bindings
if invoked on a body line.

  The following subsections give basic instructions for using Org mode
as an organizer and as an authoring system.  For details, @pxref{Top,
The Org Mode Manual, Introduction, org, The Org Manual}.

@menu
* Org Organizer::   Managing TODO lists and agendas.
* Org Authoring::   Exporting Org buffers to various formats.
@end menu

@node Org Organizer
@subsection Org as an organizer
@cindex TODO item
@cindex Org agenda

@kindex C-c C-t @r{(Org Mode)}
@findex org-todo
@vindex org-todo-keywords
  You can tag an Org entry as a @dfn{TODO} item by typing @kbd{C-c
C-t} (@code{org-todo}) anywhere in the entry.  This adds the keyword
@samp{TODO} to the heading line.  Typing @kbd{C-c C-t} again switches
the keyword to @samp{DONE}; another @kbd{C-c C-t} removes the keyword
entirely, and so forth.  You can customize the keywords used by
@kbd{C-c C-t} via the variable @code{org-todo-keywords}.

@kindex C-c C-s @r{(Org Mode)}
@kindex C-c C-d @r{(Org Mode)}
@findex org-schedule
@findex org-deadline
  Apart from marking an entry as TODO, you can attach a date to it, by
typing @kbd{C-c C-s} (@code{org-schedule}) in the entry.  This prompts
for a date by popping up the Emacs Calendar (@pxref{Calendar/Diary}),
and then adds the tag @samp{SCHEDULED}, together with the selected
date, beneath the heading line.  The command @kbd{C-c C-d}
(@code{org-deadline}) has the same effect, except that it uses the tag
@code{DEADLINE}.

@kindex C-c [ @r{(Org Mode)}
@findex org-agenda-file-to-front
@vindex org-agenda-files
  Once you have some TODO items planned in an Org file, you can add
that file to the list of @dfn{agenda files} by typing @kbd{C-c [}
(@code{org-agenda-file-to-front}).  Org mode is designed to let you
easily maintain multiple agenda files, e.g., for organizing different
aspects of your life.  The list of agenda files is stored in the
variable @code{org-agenda-files}.

@findex org-agenda
  To view items coming from your agenda files, type @kbd{M-x
org-agenda}.  This command prompts for what you want to see: a list of
things to do this week, a list of TODO items with specific keywords,
etc.
@ifnottex
@xref{Agenda Views,,,org, The Org Manual}, for details.
@end ifnottex

@node Org Authoring
@subsection Org as an authoring system
@cindex Org exporting

@findex org-export
@kindex C-c C-e @r{(Org mode)}
  You may want to format your Org notes nicely and to prepare them for
export and publication.  To export the current buffer, type @kbd{C-c
C-e} (@code{org-export}) anywhere in an Org buffer.  This command
prompts for an export format; currently supported formats include
HTML, @LaTeX{}, Texinfo, OpenDocument (@file{.odt}), iCalendar,
Markdown, man-page, and PDF@.  Some formats, such as PDF, require
certain system tools to be installed.

@vindex org-publish-project-alist
  To export several files at once to a specific directory, either
locally or over the network, you must define a list of projects
through the variable @code{org-publish-project-alist}.  See its
documentation for details.

  Org supports a simple markup scheme for applying text formatting to
exported documents:

@example
- This text is /emphasized/
- This text is *in bold*
- This text is _underlined_
- This text uses =a teletype font=

#+begin_quote
``This is a quote.''
#+end_quote

#+begin_example
This is an example.
#+end_example
@end example

  For further details, @ref{Exporting,,,org, The Org Manual}, and
@ref{Publishing,,,org, The Org Manual}.

@node TeX Mode
@section @TeX{} Mode
@cindex @TeX{} mode
@cindex @LaTeX{} mode
@cindex Sli@TeX{} mode
@cindex Doc@TeX{} mode
@cindex mode, @TeX{}
@cindex mode, @LaTeX{}
@cindex mode, Sli@TeX{}
@cindex mode, Doc@TeX{}
@findex tex-mode
@findex plain-tex-mode
@findex latex-mode
@findex slitex-mode
@findex doctex-mode
@findex bibtex-mode

  @TeX{} is a powerful text formatter written by Donald Knuth; like
GNU Emacs, it is free software.  The @TeX{} format has several
variants, including @LaTeX{}, a simplified input format for @TeX{};
Doc@TeX{}, a special file format in which the @LaTeX{} sources are
written, combining sources with documentation; and Sli@TeX{}, an
obsolete special form of @LaTeX{}@footnote{
It has been replaced by the @samp{slides} document class, which comes
with @LaTeX{}.}.

@vindex tex-default-mode
  Emacs provides a @TeX{} major mode for each of these variants: Plain
@TeX{} mode, @LaTeX{} mode, Doc@TeX{} mode, and Sli@TeX{} mode.  Emacs
selects the appropriate mode by looking at the contents of the buffer.
(This is done by invoking the @code{tex-mode} command, which is
normally called automatically when you visit a @TeX{}-like file.
@xref{Choosing Modes}.)  If the contents are insufficient to determine
this, Emacs chooses the mode specified by the variable
@code{tex-default-mode}; its default value is @code{latex-mode}.  If
Emacs does not guess right, you can select the correct variant of
@TeX{} mode using the commands @code{plain-tex-mode},
@code{latex-mode}, @code{slitex-mode}, or @code{doctex-mode}.

  The following sections document the features of @TeX{} mode and its
variants.  There are several other @TeX{}-related Emacs packages,
which are not documented in this manual:

@itemize @bullet
@item
Bib@TeX{} mode is a major mode for Bib@TeX{} files, which are commonly
used for keeping bibliographic references for @LaTeX{} documents.  For
more information, see the documentation string for the command
@code{bibtex-mode}.

@item
The Ref@TeX{} package provides a minor mode which can be used with
@LaTeX{} mode to manage bibliographic references.
@ifinfo
@xref{Top,The Ref@TeX{} Manual,,reftex}.
@end ifinfo
@ifnotinfo
For more information, see the Ref@TeX{} Info manual, which is
distributed with Emacs.
@end ifnotinfo

@item
The AUC@TeX{} package provides more advanced features for editing
@TeX{} and its related formats, including the ability to preview
@TeX{} equations within Emacs buffers.  Unlike Bib@TeX{} mode and the
Ref@TeX{} package, AUC@TeX{} is not distributed with Emacs by default.
It can be downloaded via the Package Menu (@pxref{Packages}); once
installed, see
@ifinfo
@ref{Top,The AUC@TeX{} Manual,,auctex}.
@end ifinfo
@ifnotinfo
the AUC@TeX{} manual, which is included with the package.
@end ifnotinfo
@end itemize

@menu
* TeX Editing::   Special commands for editing in TeX mode.
* LaTeX Editing:: Additional commands for LaTeX input files.
* TeX Print::     Commands for printing part of a file with TeX.
* TeX Misc::      Customization of TeX mode, and related features.
@end menu

@node TeX Editing
@subsection @TeX{} Editing Commands

@table @kbd
@item "
Insert, according to context, either @samp{``} or @samp{"} or
@samp{''} (@code{tex-insert-quote}).
@item C-j
Insert a paragraph break (two newlines) and check the previous
paragraph for unbalanced braces or dollar signs
(@code{tex-terminate-paragraph}).
@item M-x tex-validate-region
Check each paragraph in the region for unbalanced braces or dollar signs.
@item C-c @{
Insert @samp{@{@}} and position point between them (@code{tex-insert-braces}).
@item C-c @}
Move forward past the next unmatched close brace (@code{up-list}).
@end table

@findex tex-insert-quote
@kindex " @r{(@TeX{} mode)}
  In @TeX{}, the character @samp{"} is not normally used; instead,
quotations begin with @samp{``} and end with @samp{''}.  @TeX{} mode
therefore binds the @kbd{"} key to the @code{tex-insert-quote}
command.  This inserts @samp{``} after whitespace or an open brace,
@samp{"} after a backslash, and @samp{''} after any other character.

  As a special exception, if you type @kbd{"} when the text before
point is either @samp{``} or @samp{''}, Emacs replaces that preceding
text with a single @samp{"} character.  You can therefore type
@kbd{""} to insert @samp{"}, should you ever need to do so.  (You can
also use @kbd{C-q "} to insert this character.)

  In @TeX{} mode, @samp{$} has a special syntax code which attempts to
understand the way @TeX{} math mode delimiters match.  When you insert a
@samp{$} that is meant to exit math mode, the position of the matching
@samp{$} that entered math mode is displayed for a second.  This is the
same feature that displays the open brace that matches a close brace that
is inserted.  However, there is no way to tell whether a @samp{$} enters
math mode or leaves it; so when you insert a @samp{$} that enters math
mode, the previous @samp{$} position is shown as if it were a match, even
though they are actually unrelated.

@findex tex-insert-braces
@kindex C-c @{ @r{(@TeX{} mode)}
@findex up-list
@kindex C-c @} @r{(@TeX{} mode)}
  @TeX{} uses braces as delimiters that must match.  Some users prefer
to keep braces balanced at all times, rather than inserting them
singly.  Use @kbd{C-c @{} (@code{tex-insert-braces}) to insert a pair of
braces.  It leaves point between the two braces so you can insert the
text that belongs inside.  Afterward, use the command @kbd{C-c @}}
(@code{up-list}) to move forward past the close brace.  You can also
invoke @kbd{C-c @{} after marking some text: then the command encloses
the marked text in braces.

@findex tex-validate-region
@findex tex-terminate-paragraph
@kindex C-j @r{(@TeX{} mode)}
  There are two commands for checking the matching of braces.
@kbd{C-j} (@code{tex-terminate-paragraph}) checks the paragraph before
point, and inserts two newlines to start a new paragraph.  It outputs
a message in the echo area if any mismatch is found.  @kbd{M-x
tex-validate-region} checks a region, paragraph by paragraph.  The
errors are listed in an @file{*Occur*} buffer; you can use the usual
Occur mode commands in that buffer, such as @kbd{C-c C-c}, to visit a
particular mismatch (@pxref{Other Repeating Search}).

  Note that Emacs commands count square brackets and parentheses in
@TeX{} mode, not just braces.  This is not strictly correct for the
purpose of checking @TeX{} syntax.  However, parentheses and square
brackets are likely to be used in text as matching delimiters, and it
is useful for the various motion commands and automatic match display
to work with them.

@node LaTeX Editing
@subsection @LaTeX{} Editing Commands

  @LaTeX{} mode provides a few extra features not applicable to plain
@TeX{}:

@table @kbd
@item C-c C-o
Insert @samp{\begin} and @samp{\end} for @LaTeX{} block and position
point on a line between them (@code{tex-latex-block}).
@item C-c C-e
Close the innermost @LaTeX{} block not yet closed
(@code{tex-close-latex-block}).
@end table

@findex tex-latex-block
@kindex C-c C-o @r{(@LaTeX{} mode)}
  In @LaTeX{} input, @samp{\begin} and @samp{\end} tags are used to
group blocks of text.  To insert a block, type @kbd{C-c C-o}
(@code{tex-latex-block}).  This prompts for a block type, and inserts
the appropriate matching @samp{\begin} and @samp{\end} tags, leaving a
blank line between the two and moving point there.

@vindex latex-block-names
  When entering the block type argument to @kbd{C-c C-o}, you can use
the usual completion commands (@pxref{Completion}).  The default
completion list contains the standard @LaTeX{} block types.  If you
want additional block types for completion, customize the list
variable @code{latex-block-names}.

@findex tex-close-latex-block
@kindex C-c C-e @r{(@LaTeX{} mode)}
@findex latex-electric-env-pair-mode
  In @LaTeX{} input, @samp{\begin} and @samp{\end} tags must balance.
You can use @kbd{C-c C-e} (@code{tex-close-latex-block}) to insert an
@samp{\end} tag which matches the last unmatched @samp{\begin}.  It
also indents the @samp{\end} to match the corresponding @samp{\begin},
and inserts a newline after the @samp{\end} tag if point is at the
beginning of a line.  The minor mode @code{latex-electric-env-pair-mode}
automatically inserts an @samp{\end} or @samp{\begin} tag for you
when you type the corresponding one.

@node TeX Print
@subsection @TeX{} Printing Commands

  You can invoke @TeX{} as a subprocess of Emacs, supplying either
the entire contents of the buffer or just part of it (e.g., one
chapter of a larger document).

@table @kbd
@item C-c C-b
Invoke @TeX{} on the entire current buffer (@code{tex-buffer}).

@item C-c C-r
Invoke @TeX{} on the current region, together with the buffer's header
(@code{tex-region}).

@item C-c C-f
Invoke @TeX{} on the current file (@code{tex-file}).

@item C-c C-v
Preview the output from the last @kbd{C-c C-b}, @kbd{C-c C-r}, or @kbd{C-c
C-f} command (@code{tex-view}).

@item C-c C-p
Print the output from the last @kbd{C-c C-b}, @kbd{C-c C-r}, or
@kbd{C-c C-f} command (@code{tex-print}).

@item C-c @key{TAB}
Invoke Bib@TeX{} on the current file (@code{tex-bibtex-file}).
@item C-c C-l
Recenter the window showing output from @TeX{} so that the last line
can be seen (@code{tex-recenter-output-buffer}).
@item C-c C-k
Kill the @TeX{} subprocess (@code{tex-kill-job}).
@item C-c C-c
Invoke some other compilation command on the entire current buffer
(@code{tex-compile}).
@end table

@findex tex-buffer
@kindex C-c C-b @r{(@TeX{} mode)}
@findex tex-view
@kindex C-c C-v @r{(@TeX{} mode)}
@findex tex-print
@kindex C-c C-p @r{(@TeX{} mode)}
  To pass the current buffer through @TeX{}, type @kbd{C-c C-b}
(@code{tex-buffer}).  The formatted output goes in a temporary file,
normally a @file{.dvi} file.  Afterwards, you can type @kbd{C-c C-v}
(@code{tex-view}) to launch an external program, such as
@command{xdvi}, to view this output file.  You can also type @kbd{C-c
C-p} (@code{tex-print}) to print a hardcopy of the output file.

@cindex @env{TEXINPUTS} environment variable
@vindex tex-directory
  By default, @kbd{C-c C-b} runs @TeX{} in the current directory.  The
output of @TeX{} is also created in this directory.  To run @TeX{} in a
different directory, change the variable @code{tex-directory} to
the desired directory.  If your environment variable @env{TEXINPUTS}
contains relative names, or if your files contain
@samp{\input} commands with relative file names, then
@code{tex-directory} @emph{must} be @code{"."} or you will get the
wrong results.  Otherwise, it is safe to specify some other directory,
such as @code{"/tmp"}.

@vindex tex-run-command
@vindex latex-run-command
@vindex tex-dvi-view-command
@vindex tex-dvi-print-command
@vindex tex-print-file-extension
  The buffer's @TeX{} variant determines what shell command @kbd{C-c
C-b} actually runs.  In Plain @TeX{} mode, it is specified by the
variable @code{tex-run-command}, which defaults to @code{"tex"}.  In
@LaTeX{} mode, it is specified by @code{latex-run-command}, which
defaults to @code{"latex"}.  The shell command that @kbd{C-c C-v} runs
to view the @file{.dvi} output is determined by the variable
@code{tex-dvi-view-command}, regardless of the @TeX{} variant.  The
shell command that @kbd{C-c C-p} runs to print the output is
determined by the variable @code{tex-dvi-print-command}.  The variable
@code{tex-print-file-extension} can be set to the required file
extension for viewing and printing @TeX{}-compiled files.  For
example, you can set it to @file{.pdf}, and update
@code{tex-dvi-view-command} and @code{tex-dvi-print-command}
accordingly, as well as @code{latex-run-command} or
@code{tex-run-command}.

  Normally, Emacs automatically appends the output file name to the
shell command strings described in the preceding paragraph.  For
example, if @code{tex-dvi-view-command} is @code{"xdvi"}, @kbd{C-c
C-v} runs @command{xdvi @var{output-file-name}}.  In some cases,
however, the file name needs to be embedded in the command, e.g., if
you need to provide the file name as an argument to one command whose
output is piped to another.  You can specify where to put the file
name with @samp{*} in the command string.  For example,

@example
(setq tex-dvi-print-command "dvips -f * | lpr")
@end example

@findex tex-kill-job
@kindex C-c C-k @r{(@TeX{} mode)}
@findex tex-recenter-output-buffer
@kindex C-c C-l @r{(@TeX{} mode)}
  The terminal output from @TeX{}, including any error messages,
appears in a buffer called @file{*tex-shell*}.  If @TeX{} gets an
error, you can switch to this buffer and feed it input (this works as
in Shell mode; @pxref{Interactive Shell}).  Without switching to this
buffer you can scroll it so that its last line is visible by typing
@kbd{C-c C-l}.

  Type @kbd{C-c C-k} (@code{tex-kill-job}) to kill the @TeX{} process if
you see that its output is no longer useful.  Using @kbd{C-c C-b} or
@kbd{C-c C-r} also kills any @TeX{} process still running.

@findex tex-region
@kindex C-c C-r @r{(@TeX{} mode)}
  You can also pass an arbitrary region through @TeX{} by typing
@kbd{C-c C-r} (@code{tex-region}).  This is tricky, however, because
most files of @TeX{} input contain commands at the beginning to set
parameters and define macros, without which no later part of the file
will format correctly.  To solve this problem, @kbd{C-c C-r} allows
you to designate a part of the file as containing essential commands;
it is included before the specified region as part of the input to
@TeX{}.  The designated part of the file is called the @dfn{header}.

@cindex header (@TeX{} mode)
  To indicate the bounds of the header in Plain @TeX{} mode, you insert two
special strings in the file.  Insert @samp{%**start of header} before the
header, and @samp{%**end of header} after it.  Each string must appear
entirely on one line, but there may be other text on the line before or
after.  The lines containing the two strings are included in the header.
If @samp{%**start of header} does not appear within the first 100 lines of
the buffer, @kbd{C-c C-r} assumes that there is no header.

  In @LaTeX{} mode, the header begins with @samp{\documentclass} or
@samp{\documentstyle} and ends with @samp{\begin@{document@}}.  These
are commands that @LaTeX{} requires you to use in any case, so nothing
special needs to be done to identify the header.

@findex tex-file
@kindex C-c C-f @r{(@TeX{} mode)}
  The commands (@code{tex-buffer}) and (@code{tex-region}) do all of their
work in a temporary directory, and do not have available any of the auxiliary
files needed by @TeX{} for cross-references; these commands are generally
not suitable for running the final copy in which all of the cross-references
need to be correct.

  When you want the auxiliary files for cross references, use @kbd{C-c
C-f} (@code{tex-file}) which runs @TeX{} on the current buffer's file,
in that file's directory.  Before running @TeX{}, it offers to save any
modified buffers.  Generally, you need to use (@code{tex-file}) twice to
get the cross-references right.

@vindex tex-start-options
  The value of the variable @code{tex-start-options} specifies
options for the @TeX{} run.

@vindex tex-start-commands
  The value of the variable @code{tex-start-commands} specifies @TeX{}
commands for starting @TeX{}.  The default value causes @TeX{} to run
in nonstop mode.  To run @TeX{} interactively, set the variable to
@code{""}.

@vindex tex-main-file
  Large @TeX{} documents are often split into several files---one main
file, plus subfiles.  Running @TeX{} on a subfile typically does not
work; you have to run it on the main file.  In order to make
@code{tex-file} useful when you are editing a subfile, you can set the
variable @code{tex-main-file} to the name of the main file.  Then
@code{tex-file} runs @TeX{} on that file.

  The most convenient way to use @code{tex-main-file} is to specify it
in a local variable list in each of the subfiles.  @xref{File
Variables}.

@findex tex-bibtex-file
@kindex C-c TAB @r{(@TeX{} mode)}
@vindex tex-bibtex-command
  For @LaTeX{} files, you can use Bib@TeX{} to process the auxiliary
file for the current buffer's file.  Bib@TeX{} looks up bibliographic
citations in a data base and prepares the cited references for the
bibliography section.  The command @kbd{C-c @key{TAB}}
(@code{tex-bibtex-file}) runs the shell command
(@code{tex-bibtex-command}) to produce a @samp{.bbl} file for the
current buffer's file.  Generally, you need to do @kbd{C-c C-f}
(@code{tex-file}) once to generate the @samp{.aux} file, then do
@kbd{C-c @key{TAB}} (@code{tex-bibtex-file}), and then repeat @kbd{C-c C-f}
(@code{tex-file}) twice more to get the cross-references correct.

@findex tex-compile
@kindex C-c C-c @r{(@TeX{} mode)}
  To invoke some other compilation program on the current @TeX{}
buffer, type @kbd{C-c C-c} (@code{tex-compile}).  This command knows
how to pass arguments to many common programs, including
@file{pdflatex}, @file{yap}, @file{xdvi}, and @file{dvips}.  You can
select your desired compilation program using the standard completion
keys (@pxref{Completion}).

@node TeX Misc
@subsection @TeX{} Mode Miscellany

@vindex tex-shell-hook
@vindex tex-mode-hook
@vindex doctex-mode-hook
@vindex latex-mode-hook
@vindex slitex-mode-hook
@vindex plain-tex-mode-hook
  Entering any variant of @TeX{} mode runs the hooks
@code{text-mode-hook} and @code{tex-mode-hook}.  Then it runs either
@code{plain-tex-mode-hook}, @code{doctex-mode-hook},
@code{latex-mode-hook}, or @code{slitex-mode-hook}, whichever is
appropriate.  Starting the @TeX{} shell runs the hook
@code{tex-shell-hook}.  @xref{Hooks}.

@findex iso-iso2tex
@findex iso-tex2iso
@findex iso-iso2gtex
@findex iso-gtex2iso
@cindex Latin-1 @TeX{} encoding
@cindex @TeX{} encoding
  The commands @kbd{M-x iso-iso2tex}, @kbd{M-x iso-tex2iso}, @kbd{M-x
iso-iso2gtex} and @kbd{M-x iso-gtex2iso} can be used to convert
between Latin-1 encoded files and @TeX{}-encoded equivalents.

@node HTML Mode
@section SGML and HTML Modes
@cindex SGML mode
@cindex HTML mode
@cindex mode, SGML
@cindex mode, HTML
@findex sgml-mode
@findex html-mode

  The major modes for SGML and HTML provide indentation support and
commands for operating on tags.

  HTML consists of two modes---one, a basic mode called
@code{html-mode} is a slightly customized variant of SGML mode.  The
other, which is used by default for HTML files, is called
@code{mhtml-mode}, and attempts to properly handle Javascript enclosed
in a @code{<script>} element and CSS embedded in a @code{<style>}
element.

@table @kbd
@item C-c C-n
@kindex C-c C-n @r{(SGML mode)}
@findex sgml-name-char
Interactively specify a special character and insert the SGML
@samp{&}-command for that character (@code{sgml-name-char}).

@item C-c C-t
@kindex C-c C-t @r{(SGML mode)}
@findex sgml-tag
Interactively specify a tag and its attributes (@code{sgml-tag}).
This command asks you for a tag name and for the attribute values,
then inserts both the opening tag and the closing tag, leaving point
between them.

With a prefix argument @var{n}, the command puts the tag around the
@var{n} words already present in the buffer after point.  Whenever a
region is active, it puts the tag around the region (when Transient
Mark mode is off, it does this when a numeric argument of @minus{}1 is
supplied.)

@item C-c C-a
@kindex C-c C-a @r{(SGML mode)}
@findex sgml-attributes
Interactively insert attribute values for the current tag
(@code{sgml-attributes}).

@item C-c C-f
@kindex C-c C-f @r{(SGML mode)}
@findex sgml-skip-tag-forward
Skip across a balanced tag group (which extends from an opening tag
through its corresponding closing tag) (@code{sgml-skip-tag-forward}).
A numeric argument acts as a repeat count.

@item C-c C-b
@kindex C-c C-b @r{(SGML mode)}
@findex sgml-skip-tag-backward
Skip backward across a balanced tag group (which extends from an
opening tag through its corresponding closing tag)
(@code{sgml-skip-tag-backward}).  A numeric argument acts as a repeat
count.

@item C-c C-d
@kindex C-c C-d @r{(SGML mode)}
@findex sgml-delete-tag
Delete the tag at or after point, and delete the matching tag too
(@code{sgml-delete-tag}).  If the tag at or after point is an opening
tag, delete the closing tag too; if it is a closing tag, delete the
opening tag too.

@item C-c ? @var{tag} @key{RET}
@kindex C-c ? @r{(SGML mode)}
@findex sgml-tag-help
Display a description of the meaning of tag @var{tag}
(@code{sgml-tag-help}).  If the argument @var{tag} is empty, describe
the tag at point.

@item C-c /
@kindex C-c / @r{(SGML mode)}
@findex sgml-close-tag
Insert a close tag for the innermost unterminated tag
(@code{sgml-close-tag}).  If called within a tag or a comment,
close it instead of inserting a close tag.

@item C-c 8
@kindex C-c 8 @r{(SGML mode)}
@findex sgml-name-8bit-mode
Toggle a minor mode in which Latin-1 characters insert the
corresponding SGML commands that stand for them, instead of the
characters themselves (@code{sgml-name-8bit-mode}).

@item C-c C-v
@kindex C-c C-v @r{(SGML mode)}
@findex sgml-validate
Run a shell command (which you must specify) to validate the current
buffer as SGML (@code{sgml-validate}).  (In HTML mode this key
sequence runs a different command.)

@item C-c @key{TAB}
@kindex C-c TAB @r{(SGML mode)}
@findex sgml-tags-invisible
Toggle the visibility of existing tags in the buffer.  This can be
used as a cheap preview (@code{sgml-tags-invisible}).
@end table

@cindex nXML mode
@cindex mode, nXML
@cindex mode, XML
@findex nxml-mode
@cindex XML schema
  The major mode for editing XML documents is called nXML mode.  This
is a powerful major mode that can recognize many existing XML schemas
and use them to provide completion of XML elements via
@kbd{M-@key{TAB}}, as well as on-the-fly XML
validation with error highlighting.  To enable nXML mode in an
existing buffer, type @kbd{M-x nxml-mode}, or, equivalently, @kbd{M-x
xml-mode}.  Emacs uses nXML mode for files which have the extension
@file{.xml}.  For XHTML files, which have the extension @file{.xhtml},
Emacs uses HTML mode by default; you can make it use nXML mode by
customizing the variable @code{auto-mode-alist} (@pxref{Choosing
Modes}).
@ifinfo
nXML mode is described in its own manual: @xref{Top, nXML
Mode,,nxml-mode, nXML Mode}.
@end ifinfo
@ifnotinfo
nXML mode is described in an Info manual, which is distributed with
Emacs.
@end ifnotinfo

@vindex sgml-xml-mode
  You may choose to use the less powerful SGML mode for editing XML,
since XML is a strict subset of SGML@.  To enable SGML mode in an
existing buffer, type @kbd{M-x sgml-mode}.  On enabling SGML mode,
Emacs examines the buffer to determine whether it is XML; if so, it
sets the variable @code{sgml-xml-mode} to a non-@code{nil} value.
This causes SGML mode's tag insertion commands, described above, to
always insert explicit closing tags as well.

@node Nroff Mode
@section Nroff Mode

@cindex nroff
@findex nroff-mode
@vindex nroff-mode-hook
  Nroff mode, a major mode derived from Text mode, is
specialized for editing nroff files (e.g., Unix man pages).  Type
@kbd{M-x nroff-mode} to enter this mode.  Entering Nroff mode runs the
hook @code{text-mode-hook}, then @code{nroff-mode-hook}
(@pxref{Hooks}).

  In Nroff mode, nroff command lines are treated as paragraph
separators, pages are separated by @samp{.bp} commands, and comments
start with backslash-doublequote.  It also defines these commands:

@findex nroff-forward-text-line
@findex nroff-backward-text-line
@findex nroff-count-text-lines
@kindex M-n @r{(Nroff mode)}
@kindex M-p @r{(Nroff mode)}
@kindex M-? @r{(Nroff mode)}
@table @kbd
@item M-n
Move to the beginning of the next line that isn't an nroff command
(@code{nroff-forward-text-line}).  An argument is a repeat count.
@item M-p
Like @kbd{M-n} but move up (@code{nroff-backward-text-line}).
@item M-?
Displays in the echo area the number of text lines (lines that are not
nroff commands) in the region (@code{nroff-count-text-lines}).
@end table

@findex nroff-electric-mode
  Electric Nroff mode is a buffer-local minor mode that can be used
with Nroff mode.  To toggle this minor mode, type @kbd{M-x
nroff-electric-mode} (@pxref{Minor Modes}).  When the mode is on, each
time you type @key{RET} to end a line containing an nroff command that
opens a kind of grouping, the nroff command to close that grouping is
automatically inserted on the following line.

  If you use Outline minor mode with Nroff mode (@pxref{Outline
Mode}), heading lines are lines of the form @samp{.H} followed by a
number (the header level).

@node Enriched Text
@section Enriched Text
@cindex Enriched mode
@cindex mode, Enriched
@cindex enriched text
@cindex WYSIWYG
@cindex word processing
@cindex text/enriched MIME format

  Enriched mode is a minor mode for editing formatted text files in a
WYSIWYG (What You See Is What You Get) fashion.  When Enriched
mode is enabled, you can apply various formatting properties to the
text in the buffer, such as fonts and colors; upon saving the buffer,
those properties are saved together with the text, using the MIME
@samp{text/enriched} file format.

  Enriched mode is typically used with Text mode (@pxref{Text Mode}).
It is @emph{not} compatible with Font Lock mode, which is used by many
major modes, including most programming language modes, for syntax
highlighting (@pxref{Font Lock}).  Unlike Enriched mode, Font Lock
mode assigns text properties automatically, based on the current
buffer contents; those properties are not saved to disk.

  The file @file{enriched.txt} in Emacs's @code{data-directory}
serves as an example of the features of Enriched mode.

@menu
* Enriched Mode::           Entering and exiting Enriched mode.
* Hard and Soft Newlines::  There are two different kinds of newlines.
* Editing Format Info::     How to edit text properties.
* Enriched Faces::          Bold, italic, underline, etc.
* Enriched Indentation::    Changing the left and right margins.
* Enriched Justification::  Centering, setting text flush with the
                              left or right margin, etc.
* Enriched Properties::     The ``special text properties'' submenu.
@end menu

@node Enriched Mode
@subsection Enriched Mode

  Enriched mode is a buffer-local minor mode (@pxref{Minor Modes}).
When you visit a file that has been saved in the @samp{text/enriched}
format, Emacs automatically enables Enriched mode, and applies the
formatting information in the file to the buffer text.  When you save
a buffer with Enriched mode enabled, it is saved using the
@samp{text/enriched} format, including the formatting information.

@findex enriched-mode
  To create a new file of formatted text, visit the nonexistent file
and type @kbd{M-x enriched-mode}.  This command actually toggles
Enriched mode.  With a prefix argument, it enables Enriched mode if
the argument is positive, and disables Enriched mode otherwise.  If
you disable Enriched mode, Emacs no longer saves the buffer using the
@samp{text/enriched} format; any formatting properties that have been
added to the buffer remain in the buffer, but they are not saved to
disk.

@vindex enriched-translations
  Enriched mode does not save all Emacs text properties, only those
specified in the variable @code{enriched-translations}.  These include
properties for fonts, colors, indentation, and justification.

@findex format-decode-buffer
  If you visit a file and Emacs fails to recognize that it is in the
@samp{text/enriched} format, type @kbd{M-x format-decode-buffer}.
This command prompts for a file format, and re-reads the file in that
format.  Specifying the @samp{text/enriched} format automatically
enables Enriched mode.

  To view a @samp{text/enriched} file in raw form (as plain text with
markup tags rather than formatted text), use @kbd{M-x
find-file-literally} (@pxref{Visiting}).

  @xref{Format Conversion,, Format Conversion, elisp, the Emacs Lisp
Reference Manual}, for details of how Emacs recognizes and converts
file formats like @samp{text/enriched}.  @xref{Text Properties,,,
elisp, the Emacs Lisp Reference Manual}, for more information about
text properties.

@node Hard and Soft Newlines
@subsection Hard and Soft Newlines
@cindex hard newline
@cindex soft newline
@cindex newlines, hard and soft

@findex use-hard-newlines
  In Enriched mode, Emacs distinguishes between two different kinds of
newlines, @dfn{hard} newlines and @dfn{soft} newlines.  You can also
enable or disable this feature in other buffers, by typing @kbd{M-x
use-hard-newlines}.

  Hard newlines are used to separate paragraphs, or anywhere there
needs to be a line break regardless of how the text is filled; soft
newlines are used for filling.  The @key{RET} (@code{newline}) and
@kbd{C-o} (@code{open-line}) commands insert hard newlines.  The fill
commands, including Auto Fill (@pxref{Auto Fill}), insert only soft
newlines and delete only soft newlines, leaving hard newlines alone.

@c FIXME: I don't see 'unfilled' in that node.  --xfq
  Thus, when editing with Enriched mode, you should not use @key{RET}
or @kbd{C-o} to break lines in the middle of filled paragraphs.  Use
Auto Fill mode or explicit fill commands (@pxref{Fill Commands})
instead.  Use @key{RET} or @kbd{C-o} where line breaks should always
remain, such as in tables and lists.  For such lines, you may also
want to set the justification style to @code{unfilled}
(@pxref{Enriched Justification}).

@node Editing Format Info
@subsection Editing Format Information

  The easiest way to alter properties is with the @samp{Text
Properties} menu.  You can get to this menu from the @samp{Edit} menu
in the menu bar (@pxref{Menu Bar}), or with @kbd{C-mouse-2}
(@pxref{Menu Mouse Clicks}).  Some of the commands in the @samp{Text
Properties} menu are listed below (you can also invoke them with
@kbd{M-x}):

@table @code
@findex facemenu-remove-face-props
@item Remove Face Properties
Remove face properties from the region
(@code{facemenu-remove-face-props}).

@findex facemenu-remove-all
@item Remove Text Properties
Remove all text properties from the region, including face properties
(@code{facemenu-remove-all}).

@findex describe-text-properties
@cindex text properties of characters
@cindex overlays at character position
@cindex widgets at buffer position
@cindex buttons at buffer position
@item Describe Properties
List all text properties and other information about the character
following point (@code{describe-text-properties}).

@item Display Faces
Display a list of defined faces (@code{list-faces-display}).
@xref{Faces}.

@item Display Colors
Display a list of defined colors (@code{list-colors-display}).
@xref{Colors}.
@end table

@noindent
The other menu entries are described in the following sections.

@node Enriched Faces
@subsection Faces in Enriched Text

  The following commands can be used to add or remove faces
(@pxref{Faces}).  Each applies to the text in the region if the mark
is active, and to the next self-inserting character if the mark is
inactive.  With a prefix argument, each command applies to the next
self-inserting character even if the region is active.

@table @kbd
@kindex M-o d @r{(Enriched mode)}
@findex facemenu-set-default
@item M-o d
Remove all @code{face} properties (@code{facemenu-set-default}).

@kindex M-o b @r{(Enriched mode)}
@findex facemenu-set-bold
@item M-o b
Apply the @code{bold} face (@code{facemenu-set-bold}).

@kindex M-o i @r{(Enriched mode)}
@findex facemenu-set-italic
@item M-o i
Apply the @code{italic} face (@code{facemenu-set-italic}).

@kindex M-o l @r{(Enriched mode)}
@findex facemenu-set-bold-italic
@item M-o l
Apply the @code{bold-italic} face (@code{facemenu-set-bold-italic}).

@kindex M-o u @r{(Enriched mode)}
@findex facemenu-set-underline
@item M-o u
Apply the @code{underline} face (@code{facemenu-set-underline}).

@kindex M-o o @r{(Enriched mode)}
@findex facemenu-set-face
@item M-o o @var{face} @key{RET}
Apply the face @var{face} (@code{facemenu-set-face}).

@findex facemenu-set-foreground
@item M-x facemenu-set-foreground
Prompt for a color (@pxref{Colors}), and apply it as a foreground
color.

@findex facemenu-set-background
@item M-x facemenu-set-background
Prompt for a color, and apply it as a background color.
@end table

@noindent
These commands are also available via the Text Properties menu.

  A self-inserting character normally inherits the face properties
(and most other text properties) from the preceding character in the
buffer.  If you use one of the above commands to specify the face for
the next self-inserting character, that character will not inherit the
faces properties from the preceding character, but it will still
inherit other text properties.

  Enriched mode defines two additional faces: @code{excerpt} and
@code{fixed}.  These correspond to codes used in the text/enriched
file format.  The @code{excerpt} face is intended for quotations; by
default, it appears the same as @code{italic}.  The @code{fixed} face
specifies fixed-width text; by default, it appears the same as
@code{bold}.

@node Enriched Indentation
@subsection Indentation in Enriched Text

  In Enriched mode, you can specify different amounts of indentation
for the right or left margin of a paragraph or a part of a paragraph.
These margins also affect fill commands such as @kbd{M-q}
(@pxref{Filling}).

  The Indentation submenu of Text Properties offers commands
for specifying indentation:

@table @code
@kindex C-x TAB @r{(Enriched mode)}
@findex increase-left-margin
@item Indent More
Indent the region by 4 columns (@code{increase-left-margin}).  In
Enriched mode, this command is also available on @kbd{C-x @key{TAB}}; if
you supply a numeric argument, that says how many columns to add to the
margin (a negative argument reduces the number of columns).

@item Indent Less
Remove 4 columns of indentation from the region.

@item Indent Right More
Make the text narrower by indenting 4 columns at the right margin.

@item Indent Right Less
Remove 4 columns of indentation from the right margin.
@end table

@vindex standard-indent
  The variable @code{standard-indent} specifies how many columns these
commands should add to or subtract from the indentation.  The default
value is 4.  The default right margin for Enriched mode is controlled
by the variable @code{fill-column}, as usual.

@kindex C-c [ @r{(Enriched mode)}
@kindex C-c ] @r{(Enriched mode)}
@findex set-left-margin
@findex set-right-margin
  You can also type @kbd{C-c [} (@code{set-left-margin}) and @kbd{C-c
]} (@code{set-right-margin}) to set the left and right margins.  You
can specify the margin width with a numeric argument; otherwise these
commands prompt for a value via the minibuffer.

  The fill prefix, if any, works in addition to the specified paragraph
indentation: @kbd{C-x .} does not include the specified indentation's
whitespace in the new value for the fill prefix, and the fill commands
look for the fill prefix after the indentation on each line.  @xref{Fill
Prefix}.

@node Enriched Justification
@subsection Justification in Enriched Text
@cindex justification style

  In Enriched mode, you can use the following commands to specify
various @dfn{justification styles} for filling.  These commands apply
to the paragraph containing point, or, if the region is active, to all
paragraphs overlapping the region.

@table @kbd
@kindex M-j l @r{(Enriched mode)}
@findex set-justification-left
@item M-j l
Align lines to the left margin (@code{set-justification-left}).

@kindex M-j r @r{(Enriched mode)}
@findex set-justification-right
@item M-j r
Align lines to the right margin (@code{set-justification-right}).

@kindex M-j b @r{(Enriched mode)}
@findex set-justification-full
@item M-j b
Align lines to both margins, inserting spaces in the middle of the
line to achieve this (@code{set-justification-full}).

@kindex M-j c @r{(Enriched mode)}
@kindex M-S @r{(Enriched mode)}
@findex set-justification-center
@item M-j c
@itemx M-S
Center lines between the margins (@code{set-justification-center}).

@kindex M-j u @r{(Enriched mode)}
@findex set-justification-none
@item M-j u
Turn off filling entirely (@code{set-justification-none}).  The fill
commands do nothing on text with this setting.  You can, however,
still indent the left margin.
@end table

@vindex default-justification
  You can also specify justification styles using the Justification
submenu in the Text Properties menu.  The default justification style
is specified by the per-buffer variable @code{default-justification}.
Its value should be one of the symbols @code{left}, @code{right},
@code{full}, @code{center}, or @code{none}; their meanings correspond
to the commands above.

@node Enriched Properties
@subsection Setting Other Text Properties

  The Special Properties submenu of Text Properties has entries for
adding or removing four other text properties: @code{read-only},
(which disallows alteration of the text), @code{invisible} (which
hides text), @code{intangible} (which disallows moving point within
the text), and @code{charset} (which is important for selecting a
proper font to display a character).  The @samp{Remove Special} menu
item removes all of these special properties from the text in the
region.

  The @code{invisible} and @code{intangible} properties are not saved.

@vindex enriched-allow-eval-in-display-props
@cindex security, when displaying enriched text
  Enriched mode also supports saving and restoring @code{display}
properties (@pxref{Display Property,,,elisp, the Emacs Lisp Reference
Manual}), which affect how text is displayed on the screen, and also
allow displaying images and strings that come from sources other than
buffer text.  The @code{display} properties also support execution of
arbitrary Lisp forms as part of processing the property for display,
thus providing a means to dynamically tailor the display to some
conditions that can only be known at display time.  Since execution of
arbitrary Lisp opens Emacs to potential attacks, especially when the
source of enriched text is outside of Emacs or even outside of your
system (e.g., if it was received in an email message), such execution
is by default disabled in Enriched mode.  You can enable it by
customizing the variable @code{enriched-allow-eval-in-display-props}
to a non-@code{nil} value.

@node Text Based Tables
@section Editing Text-based Tables
@cindex table mode
@cindex text-based tables

  The @code{table} package provides commands to easily edit text-based
tables.  Here is an example of what such a table looks like:

@smallexample
@group
+-----------------+--------------------------------+-----------------+
|     Command     |          Description           |   Key Binding   |
+-----------------+--------------------------------+-----------------+
|  forward-char   |Move point right N characters   |       C-f       |
|                 |(left if N is negative).        |                 |
|                 |                                |                 |
+-----------------+--------------------------------+-----------------+
|  backward-char  |Move point left N characters    |       C-b       |
|                 |(right if N is negative).       |                 |
|                 |                                |                 |
+-----------------+--------------------------------+-----------------+
@end group
@end smallexample

  When Emacs recognizes such a stretch of text as a table
(@pxref{Table Recognition}), editing the contents of each table cell
will automatically resize the table, whenever the contents become too
large to fit in the cell.  You can use the commands defined in the
following sections for navigating and editing the table layout.

@findex table-fixed-width-mode
  Type @kbd{M-x table-fixed-width-mode} to toggle the automatic table
resizing feature.

@menu
* Table Definition::          What is a text based table.
* Table Creation::            How to create a table.
* Table Recognition::         How to activate and deactivate tables.
* Cell Commands::             Cell-oriented commands in a table.
* Cell Justification::        Justifying cell contents.
* Table Rows and Columns::    Inserting and deleting rows and columns.
* Table Conversion::          Converting between plain text and tables.
* Table Misc::                Table miscellany.
@end menu

@node Table Definition
@subsection What is a Text-based Table?
@cindex cells, for text-based tables

  A @dfn{table} consists of a rectangular text area which is divided
into @dfn{cells}.  Each cell must be at least one character wide and
one character high, not counting its border lines.  A cell can be
subdivided into more cells, but they cannot overlap.

  Cell border lines are drawn with three special characters, specified
by the following variables:

@table @code
@vindex table-cell-vertical-char
@item table-cell-vertical-char
The character used for vertical lines.  The default is @samp{|}.

@vindex table-cell-horizontal-chars
@item table-cell-horizontal-chars
The characters used for horizontal lines.  The default is @samp{"-="}.

@vindex table-cell-intersection-char
@item table-cell-intersection-char
The character used for the intersection of horizontal and vertical
lines.  The default is @samp{+}.
@end table

@noindent
The following are examples of @emph{invalid} tables:

@example
   +-----+       +--+    +-++--+
   |     |       |  |    | ||  |
   |     |       |  |    | ||  |
   +--+  |    +--+--+    +-++--+
   |  |  |    |  |  |    +-++--+
   |  |  |    |  |  |    | ||  |
   +--+--+    +--+--+    +-++--+
      a          b          c
@end example

@noindent
From left to right:

@enumerate a
@item
Overlapped cells or non-rectangular cells are not allowed.
@item
The border must be rectangular.
@item
Cells must have a minimum width/height of one character.
@end enumerate

@node Table Creation
@subsection Creating a Table
@cindex create a text-based table
@cindex table creation

@findex table-insert
  To create a text-based table from scratch, type @kbd{M-x
table-insert}.  This command prompts for the number of table columns,
the number of table rows, cell width and cell height.  The cell width
and cell height do not include the cell borders; each can be specified
as a single integer (which means each cell is given the same
width/height), or as a sequence of integers separated by spaces or
commas (which specify the width/height of the individual table
columns/rows, counting from left to right for table columns and from
top to bottom for table rows).  The specified table is then inserted
at point.

  The table inserted by @kbd{M-x table-insert} contains special text
properties, which tell Emacs to treat it specially as a text-based
table.  If you save the buffer to a file and visit it again later,
those properties are lost, and the table appears to Emacs as an
ordinary piece of text.  See the next section, for how to convert it
back into a table.

@node Table Recognition
@subsection Table Recognition
@cindex table recognition

@findex table-recognize
@findex table-unrecognize
  Existing text-based tables in a buffer, which lack the special text
properties applied by @kbd{M-x table-insert}, are not treated
specially as tables.  To apply those text properties, type @kbd{M-x
table-recognize}.  This command scans the current buffer,
@dfn{recognizes} valid table cells, and applies the relevant text
properties.  Conversely, type @kbd{M-x table-unrecognize} to
@dfn{unrecognize} all tables in the current buffer, removing the
special text properties and converting tables back to plain text.

  You can also use the following commands to selectively recognize or
unrecognize tables:

@table @kbd
@findex table-recognize-region
@item M-x table-recognize-region
Recognize tables within the current region.

@findex table-unrecognize-region
@item M-x table-unrecognize-region
Unrecognize tables within the current region.

@findex table-recognize-table
@item M-x table-recognize-table
Recognize the table at point and activate it.

@findex table-unrecognize-table
@item M-x table-unrecognize-table
Deactivate the table at point.

@findex table-recognize-cell
@item M-x table-recognize-cell
Recognize the cell at point and activate it.

@findex table-unrecognize-cell
@item M-x table-unrecognize-cell
Deactivate the cell at point.
@end table

  @xref{Table Conversion}, for another way to recognize a table.

@node Cell Commands
@subsection Commands for Table Cells

@findex table-forward-cell
@findex table-backward-cell
  The commands @kbd{M-x table-forward-cell} and @kbd{M-x
table-backward-cell} move point from the current cell to an adjacent
cell.  The order is cyclic: when point is in the last cell of a table,
@kbd{M-x table-forward-cell} moves to the first cell.  Likewise, when
point is on the first cell, @kbd{M-x table-backward-cell} moves to the
last cell.

@findex table-span-cell
  @kbd{M-x table-span-cell} prompts for a direction---right, left,
above, or below---and merges the current cell with the adjacent cell
in that direction.  This command signals an error if the merge would
result in an illegitimate cell layout.

@findex table-split-cell
@findex table-split-cell-vertically
@findex table-split-cell-horizontally
@cindex text-based tables, splitting cells
@cindex splitting table cells
  @kbd{M-x table-split-cell} splits the current cell vertically or
horizontally, prompting for the direction with the minibuffer.  To
split in a specific direction, use @kbd{M-x
table-split-cell-vertically} and @kbd{M-x
table-split-cell-horizontally}.  When splitting vertically, the old
cell contents are automatically split between the two new cells.  When
splitting horizontally, you are prompted for how to divide the cell
contents, if the cell is non-empty; the options are @samp{split}
(divide the contents at point), @samp{left} (put all the contents in
the left cell), and @samp{right} (put all the contents in the right
cell).

  The following commands enlarge or shrink a cell.  By default, they
resize by one row or column; if a numeric argument is supplied, that
specifies the number of rows or columns to resize by.

@table @kbd
@findex table-heighten-cell
@item M-x table-heighten-cell
Enlarge the current cell vertically.

@findex table-shorten-cell
@item M-x table-shorten-cell
Shrink the current cell vertically.

@findex table-widen-cell
@item M-x table-widen-cell
Enlarge the current cell horizontally.

@findex table-narrow-cell
@item M-x table-narrow-cell
Shrink the current cell horizontally.
@end table

@node Cell Justification
@subsection Cell Justification
@cindex justification in text-based tables

  The command @kbd{M-x table-justify} imposes @dfn{justification} on
one or more cells in a text-based table.  Justification determines how
the text in the cell is aligned, relative to the edges of the cell.
Each cell in a table can be separately justified.

@findex table-justify
  @kbd{M-x table-justify} first prompts for what to justify; the
options are @samp{cell} (just the current cell), @samp{column} (all
cells in the current table column) and @samp{row} (all cells in the
current table row).  The command then prompts for the justification
style; the options are @code{left}, @code{center}, @code{right},
@code{top}, @code{middle}, @code{bottom}, or @code{none} (meaning no
vertical justification).

  Horizontal and vertical justification styles are specified
independently, and both types can be in effect simultaneously; for
instance, you can call @kbd{M-x table-justify} twice, once to specify
@code{right} justification and once to specify @code{bottom}
justification, to align the contents of a cell to the bottom right.

@vindex table-detect-cell-alignment
  The justification style is stored in the buffer as a text property,
and is lost when you kill the buffer or exit Emacs.  However, the
table recognition commands, such as @kbd{M-x table-recognize}
(@pxref{Table Recognition}), attempt to determine and re-apply each
cell's justification style, by examining its contents.  To disable
this feature, change the variable @code{table-detect-cell-alignment}
to @code{nil}.

@node Table Rows and Columns
@subsection Table Rows and Columns
@cindex inserting rows and columns in text-based tables

@findex table-insert-row
  @kbd{M-x table-insert-row} inserts a row of cells before the current
table row.  The current row, together with point, is pushed down past
the new row.  To insert a row after the last row at the bottom of a
table, invoke this command with point below the table, just below the
bottom edge.  You can insert more than one row at a time by using a
numeric prefix argument.

@c A numeric prefix argument specifies the number of rows to insert.

@findex table-insert-column
  Similarly, @kbd{M-x table-insert-column} inserts a column of cells
to the left of the current table column.  To insert a column to the
right side of the rightmost column, invoke this command with point to
the right of the rightmost column, outside the table.  A numeric
prefix argument specifies the number of columns to insert.

@cindex deleting rows and column in text-based tables
  @kbd{M-x table-delete-column} deletes the column of cells at point.
Similarly, @kbd{M-x table-delete-row} deletes the row of cells at
point.  A numeric prefix argument to either command specifies the
number of columns or rows to delete.

@node Table Conversion
@subsection Converting Between Plain Text and Tables
@cindex text to table
@cindex table to text

@findex table-capture
  The command @kbd{M-x table-capture} captures plain text in a region
and turns it into a table.  Unlike @kbd{M-x table-recognize}
(@pxref{Table Recognition}), the original text does not need to have a
table appearance; it only needs to have a logical table-like
structure.

  For example, suppose we have the following numbers, which are
divided into three lines and separated horizontally by commas:

@example
1, 2, 3, 4
5, 6, 7, 8
, 9, 10
@end example

@noindent
Invoking @kbd{M-x table-capture} on that text produces this table:

@example
+-----+-----+-----+-----+
|1    |2    |3    |4    |
+-----+-----+-----+-----+
|5    |6    |7    |8    |
+-----+-----+-----+-----+
|     |9    |10   |     |
+-----+-----+-----+-----+
@end example

@findex table-release
  @kbd{M-x table-release} does the opposite: it converts a table back
to plain text, removing its cell borders.

  One application of this pair of commands is to edit a text in
layout.  Look at the following three paragraphs:

@example
table-capture is a powerful command.
Here are some things it can do:

Parse Cell Items   Using row and column delimiter regexps,
                   it parses the specified text area and
                   extracts cell items into a table.
@end example

@noindent
Applying @code{table-capture} to a region containing the above text,
with empty strings for the column and row delimiter regexps, creates a
table with a single cell like the following one.

@smallexample
@group
+----------------------------------------------------------+
|table-capture is a powerful command.                      |
|Here are some things it can do:                           |
|                                                          |
|Parse Cell Items   Using row and column delimiter regexps,|
|                   it parses the specified text area and  |
|                   extracts cell items into a table.      |
+----------------------------------------------------------+
@end group
@end smallexample

@noindent
We can then use the cell splitting commands (@pxref{Cell Commands}) to
subdivide the table so that each paragraph occupies a cell:

@smallexample
+----------------------------------------------------------+
|table-capture is a powerful command.                      |
|Here are some things it can do:                           |
+-----------------+----------------------------------------+
|Parse Cell Items | Using row and column delimiter regexps,|
|                 | it parses the specified text area and  |
|                 | extracts cell items into a table.      |
+-----------------+----------------------------------------+
@end smallexample

@noindent
Each cell can now be edited independently without affecting the layout
of other cells.  When finished, we can invoke @kbd{M-x table-release}
to convert the table back to plain text.

@node Table Misc
@subsection Table Miscellany

@cindex table dimensions
@findex table-query-dimension
  The command @code{table-query-dimension} reports the layout of the
table and table cell at point.  Here is an example of its output:

@smallexample
Cell: (21w, 6h), Table: (67w, 16h), Dim: (2c, 3r), Total Cells: 5
@end smallexample

@noindent
This indicates that the current cell is 21 characters wide and 6 lines
high, the table is 67 characters wide and 16 lines high with 2 columns
and 3 rows, and a total of 5 cells.

@findex table-insert-sequence
  @kbd{M-x table-insert-sequence} traverses the cells of a table
inserting a sequence of text strings into each cell as it goes.  It
asks for the base string of the sequence, and then produces the
sequence by ``incrementing'' the base string, either numerically (if
the base string ends in numerical characters) or in the
@acronym{ASCII} order.  In addition to the base string, the command
prompts for the number of elements in the sequence, the increment, the
cell interval, and the justification of the text in each cell.

@cindex table for HTML and LaTeX
@findex table-generate-source
  @kbd{M-x table-generate-source} generates a table formatted for a
specific markup language.  It asks for a language (which must be one
of @code{html}, @code{latex}, @code{cals}, @code{wiki} or
@code{mediawiki}), a destination buffer in which to put the result,
and a table caption, and then inserts the generated table into the
specified buffer.  The default destination buffer is
@code{table.@var{lang}}, where @var{lang} is the language you
specified.

@node Two-Column
@section Two-Column Editing
@cindex two-column editing
@cindex splitting columns
@cindex columns, splitting

  Two-column mode lets you conveniently edit two side-by-side columns
of text.  It uses two side-by-side windows, each showing its own
buffer.  There are three ways to enter two-column mode:

@table @asis
@item @kbd{@key{F2} 2} or @kbd{C-x 6 2}
@kindex F2 2
@kindex C-x 6 2
@findex 2C-two-columns
Enter two-column mode with the current buffer on the left, and on the
right, a buffer whose name is based on the current buffer's name
(@code{2C-two-columns}).  If the right-hand buffer doesn't already
exist, it starts out empty; the current buffer's contents are not
changed.

This command is appropriate when the current buffer is empty or contains
just one column and you want to add another column.

@item @kbd{@key{F2} s} or @kbd{C-x 6 s}
@kindex F2 s
@kindex C-x 6 s
@findex 2C-split
Split the current buffer, which contains two-column text, into two
buffers, and display them side by side (@code{2C-split}).  The current
buffer becomes the left-hand buffer, but the text in the right-hand
column is moved into the right-hand buffer.  The current column
specifies the split point.  Splitting starts with the current line and
continues to the end of the buffer.

This command is appropriate when you have a buffer that already contains
two-column text, and you wish to separate the columns temporarily.

@item @kbd{@key{F2} b @var{buffer} @key{RET}}
@itemx @kbd{C-x 6 b @var{buffer} @key{RET}}
@kindex F2 b
@kindex C-x 6 b
@findex 2C-associate-buffer
Enter two-column mode using the current buffer as the left-hand buffer,
and using buffer @var{buffer} as the right-hand buffer
(@code{2C-associate-buffer}).
@end table

  @kbd{@key{F2} s} or @kbd{C-x 6 s} looks for a column separator, which
is a string that appears on each line between the two columns.  You can
specify the width of the separator with a numeric argument to
@kbd{@key{F2} s}; that many characters, before point, constitute the
separator string.  By default, the width is 1, so the column separator
is the character before point.

  When a line has the separator at the proper place, @kbd{@key{F2} s}
puts the text after the separator into the right-hand buffer, and
deletes the separator.  Lines that don't have the column separator at
the proper place remain unsplit; they stay in the left-hand buffer, and
the right-hand buffer gets an empty line to correspond.  (This is the
way to write a line that spans both columns while in two-column
mode: write it in the left-hand buffer, and put an empty line in the
right-hand buffer.)

@kindex F2 RET
@kindex C-x 6 RET
@findex 2C-newline
  The command @kbd{@key{F2} @key{RET}} or @kbd{C-x 6 @key{RET}}
(@code{2C-newline}) inserts a newline in each of the two buffers at
corresponding positions.  This is the easiest way to add a new line to
the two-column text while editing it in split buffers.

@kindex F2 1
@kindex C-x 6 1
@findex 2C-merge
  When you have edited both buffers as you wish, merge them with
@kbd{@key{F2} 1} or @kbd{C-x 6 1} (@code{2C-merge}).  This copies the
text from the right-hand buffer as a second column in the other buffer.
To go back to two-column editing, use @kbd{@key{F2} s}.

@kindex F2 d
@kindex C-x 6 d
@findex 2C-dissociate
  Use @kbd{@key{F2} d} or @kbd{C-x 6 d} to dissociate the two buffers,
leaving each as it stands (@code{2C-dissociate}).  If the other buffer,
the one not current when you type @kbd{@key{F2} d}, is empty,
@kbd{@key{F2} d} kills it.