[gnu-emacs] / doc / emacs / text.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
@c   2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
@c   Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Text, Programs, Indentation, Top
@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.
@iftex
@xref{Outline Mode}.
@end iftex

@cindex nXML mode
@cindex mode, XML
@cindex mode, nXML
@findex nxml-mode
  Emacs has other major modes for text which contains ``embedded''
commands, such as @TeX{} and La@TeX{} (@pxref{TeX Mode}); HTML and
SGML (@pxref{HTML Mode}); XML (@pxref{Top, nXML Mode,,nxml-mode, nXML
Mode}); and Groff and Nroff (@pxref{Nroff Mode}).  In addition, you
can edit formatted text in WYSIWYG style (``what you see is what you
get''), using Enriched mode (@pxref{Formatted Text}).

@cindex ASCII art
  If you need to edit pictures made out of text characters (commonly
referred to as ``ASCII art''), 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


@cindex skeletons
@cindex templates
@cindex autotyping
@cindex automatic typing
  The ``automatic typing'' features may be useful when writing text.
@inforef{Top,, autotype}.

@menu
* Words::               Moving over and killing words.
* Sentences::           Moving over and killing sentences.
* Paragraphs::          Moving over paragraphs.
* Pages::               Moving over pages.
* Filling::             Filling or justifying text.
* Case::                Changing the case of text.
* Text Mode::           The major modes for editing text files.
* Outline Mode::        Editing outlines.
* TeX Mode::            Editing input to the formatter TeX.
* HTML Mode::           Editing HTML and SGML files.
* Nroff Mode::          Editing input to the formatter nroff.
* Formatted Text::      Editing formatted text directly in WYSIWYG fashion.
* Text Based Tables::   Editing text-based tables in WYSIWYG fashion.
@end menu

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

  Emacs has commands for moving over or operating on words.  By convention,
the keys for them are all Meta characters.

@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-@@
Mark 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-@@
@findex mark-word
  To operate on the next @var{n} words with an operation which acts on
the region, use the command @kbd{M-@@} (@code{mark-word}).  This
command does not move point, but sets the mark where @kbd{M-f} would
move to.  Once the mark is active, each additional @kbd{M-@@} advances
the mark by one additional word.  @kbd{M-@@} also accepts a numeric
argument that says how many words to scan for the place to put the
mark.

  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}.

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

  The Emacs commands for manipulating sentences and paragraphs are mostly
on Meta keys, so as to be 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} and @kbd{M-e} (@code{backward-sentence} and
@code{forward-sentence}) move to the beginning and end of the current
sentence, respectively.  They 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; they consider
a sentence to end 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 makes a distinction
between periods that end a sentence and periods that indicate
abbreviations; that enables the Emacs sentence commands to distinguish,
too.  These commands do not stop for 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}) in related ways.

@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 do not use periods to indicate the end of a sentence.
For example, sentences in Thai end with a double space but without a
period.  Set the variable @code{sentence-end-without-period} to
@code{t} in such cases.

@node Paragraphs
@section Paragraphs
@cindex paragraphs
@cindex manipulating paragraphs
@kindex M-@{
@kindex M-@}
@findex backward-paragraph
@findex forward-paragraph

  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

  @kbd{M-@{} moves to the beginning of the current or previous
paragraph, while @kbd{M-@}} moves to the end of the current or next
paragraph.  Blank lines and text-formatter command lines separate
paragraphs and are not considered part of any paragraph.  If there is
a blank line before the paragraph, @kbd{M-@{} moves to the blank line,
because that is convenient in practice.

  In Text mode, an indented line is not a paragraph break.  If you
want indented lines to have this effect, use Paragraph-Indent Text
mode instead.  @xref{Text Mode}.

  In major modes for programs, paragraphs begin and end only at blank
lines.  This makes the paragraph commands useful, even though there
are no paragraphs as such in a program.

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

@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), the paragraph following point is surrounded by point
and mark.  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; furthermore, each subsequent @kbd{M-h} further advances the
mark by one paragraph.

@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 regexp that should match any line
that either starts or separates paragraphs.  The value of
@code{paragraph-separate} is another regexp that should match only 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}.  Each regular expression must match at the
left margin.  For example, in Fundamental mode, @code{paragraph-start}
is @w{@code{"\f\\|[ \t]*$"}}, and @code{paragraph-separate} is
@w{@code{"[ \t\f]*$"}}.

  Normally it is desirable for page boundaries to separate paragraphs.
The default values of these variables recognize the usual separator for
pages.

@node Pages
@section Pages

@cindex pages
@cindex formfeed character
  Within some text files, text is divided into @dfn{pages}, which are
delimited by the @dfn{formfeed character} (@acronym{ASCII} code 12,
sometimes denoted as @key{control-L}).  When you print hardcopy for a
file, the formfeed character forces a page break: each page of the
file goes on a separate page on paper.  Most Emacs commands treat the
formfeed character just like any other character: you can insert it
with @kbd{C-q C-l}, and delete it with @key{DEL}.  However, since
pages are often meaningful divisions of the file, Emacs provides
commands to move over them and operate on them.

@table @kbd
@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

@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 and the mark at the end.  The page
delimiter at the end is included (the mark follows it).  The page
delimiter at the front is excluded (point follows it).

  @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.  The reason @kbd{C-x C-p} includes only the
following page delimiter in the region is to ensure that.

  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 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 leaves it unfilled.  When you edit formatted text, you can specify
a style of filling for each portion of the text (@pxref{Formatted
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.
* Refill::         Keeping paragraphs filled.
* Longlines::      Editing text with very long lines.
@end menu

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

  @dfn{Auto Fill} mode is a minor mode in which lines are broken
automatically when they become too wide.  Breaking happens only when
you type a @key{SPC} or @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
  @kbd{M-x auto-fill-mode} turns Auto Fill mode on if it was off, or off
if it was on.  With a positive numeric argument it always turns Auto
Fill mode on, and with a negative argument always turns it off.  You can
see when Auto Fill mode is in effect by the presence of the word
@samp{Fill} in the mode line, inside the parentheses.  Auto Fill mode is
a minor mode which is enabled or disabled for each buffer individually.
@xref{Minor Modes}.

  In Auto Fill mode, lines are broken automatically at spaces when they
get longer than the desired width.  Line breaking and rearrangement
takes place only when you type @key{SPC} or @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} (recall that a newline is really a
control-J).  Also, @kbd{C-o} inserts a newline without line breaking.

  Auto Fill mode works well with programming-language modes, because it
indents new lines with @key{TAB}.  If a line ending in a comment gets
too long, the text of the comment is split into two comment lines.
Optionally, new comment delimiters are inserted at the end of the first
line and the beginning of the second so that each line is a separate
comment; the variable @code{comment-multi-line} controls the choice
(@pxref{Comments}).

  Adaptive filling (@pxref{Adaptive Fill}) works for Auto Filling as
well as for explicit fill commands.  It takes a fill prefix
automatically from the second or first line of a paragraph.

  Auto Fill mode does not refill entire paragraphs; it can break lines but
cannot merge lines.  So editing in the middle of a paragraph can result in
a paragraph that is not correctly filled.  The easiest way to make the
paragraph properly filled again is usually with the explicit fill commands.
@ifnottex
@xref{Fill Commands}.
@end ifnottex

  Many users like Auto Fill mode and want to use it in all text files.
The section on init files says how to arrange this permanently for yourself.
@xref{Init File}.

@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-o M-s
Center a line.
@end table

@kindex M-q
@findex fill-paragraph
  To refill a paragraph, use the command @kbd{M-q}
(@code{fill-paragraph}).  This operates on the paragraph that point is
inside, or the one after point if point is between paragraphs.
Refilling works by removing all the line-breaks, then inserting new
ones where necessary.  When there is an active region, this command
operates on the text within the region like @code{fill-region}.

@findex fill-region
  To refill many paragraphs, use @kbd{M-x fill-region}, which
finds the paragraphs in the region and fills each of them.

@findex fill-region-as-paragraph
  @kbd{M-q} and @code{fill-region} use the same criteria as @kbd{M-h}
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}.)  Another way to control justification, and choose
other styles of filling, is with the @code{justification} text
property; see @ref{Format Justification}.

@kindex M-o M-s @r{(Text mode)}
@cindex centering
@findex center-line
  The command @kbd{M-o M-s} (@code{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}).

@vindex fill-column
@kindex C-x f
@findex set-fill-column
  The maximum line width for filling is in the variable
@code{fill-column}.  Altering the value of @code{fill-column} makes it
local to the current buffer; until that time, the default value is in
effect.  The default is initially 70.  @xref{Locals}.  The easiest way
to set @code{fill-column} 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.

  Emacs commands normally consider 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 and not the end of a sentence.  To preserve
the distinction between these two ways of using a period, the fill
commands do not break a line after a period followed by just one space.

  If the variable @code{sentence-end-double-space} is @code{nil}, the
fill commands expect and leave just one space at the end of a sentence.
Ordinarily this variable is @code{t}, so the fill commands insist on
two spaces for the end of a sentence, as explained above.  @xref{Sentences}.

@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
  The variable @code{fill-nobreak-predicate} is a hook (an abnormal
hook, @pxref{Hooks}) specifying additional conditions where
line-breaking is not allowed.  Each function is called with no
arguments, with point at a place where Emacs is considering breaking
the line.  If a function returns a non-@code{nil} value, then that's
a bad place to break the line.  Two standard functions you can use are
@code{fill-single-word-nobreak-p} (don't break after the first word of
a sentence or before the last) and @code{fill-french-nobreak-p} (don't
break after @samp{(} or before @samp{)}, @samp{:} or @samp{?}).

@node Fill Prefix
@subsection The Fill Prefix

@cindex fill prefix
  To fill a paragraph in which each line starts with a special marker
(which might be a few spaces, giving an indented paragraph), you can use
the @dfn{fill prefix} feature.  The fill prefix is a string that Emacs
expects every line to start with, and which is not included in filling.
You can specify a fill prefix explicitly; Emacs can also deduce the
fill prefix 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.  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{Format 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 Refill
@subsection Refill Mode
@cindex refilling text, word processor style
@cindex modes, Refill
@cindex Refill minor mode

  Refill minor mode provides support for keeping paragraphs filled as
you type or modify them in other ways.  It provides an effect similar
to typical word processor behavior.  This works by running a
paragraph-filling command at suitable times.

  To toggle the use of Refill mode in the current buffer, type
@kbd{M-x refill-mode}.  When you are typing text, only characters
which normally trigger auto filling, like the space character, will
trigger refilling.  This is to avoid making it too slow.  Apart from
self-inserting characters, other commands which modify the text cause
refilling.

  The current implementation is preliminary and not robust.  You can
get better ``line wrapping'' behavior using Longlines mode.
@xref{Longlines}.  However, Longlines mode has an important
side-effect: the newlines that it inserts for you are not saved to
disk, so the files that you make with Longlines mode will appear to be
completely unfilled if you edit them without Longlines mode.

@node Longlines
@subsection Long Lines Mode
@cindex refilling text, word processor style
@cindex modes, Long Lines
@cindex word wrap
@cindex Long Lines minor mode

  Sometimes, you may come across ``unfilled'' text files, which Emacs
normally displays as a bunch of extremely long lines.  Comfortably
reading and editing such files normally requires ``word wrap'', a
feature that breaks up each long text line into multiple screen lines
in a readable manner---by putting the breaks at word boundaries.  Many
text editors, such as those built into many web browsers, perform word
wrapping by default.

  There are two different minor modes in Emacs that perform word
wrapping.  The first is Visual Line mode, which does it by altering
the behavior of screen line continuation.  @xref{Visual Line Mode},
for information about Visual Line mode.

@findex longlines-mode
  Instead of using Visual Line mode, you can use a minor mode called
Long Lines mode.  Long Lines mode wraps lines by inserting or deleting
@dfn{soft newlines} as you type (@pxref{Hard and Soft Newlines}).
These soft newlines won't show up when you save the buffer into a
file, or when you copy the text into the kill ring, clipboard, or a
register.  Unlike Visual Line mode, Lone Lines mode breaks long lines
at the fill column (@pxref{Fill Commands}), rather than the right
window edge.  To enable Long Lines mode, type @kbd{M-x
longlines-mode}.  If the text is full of long lines, this also
immediately ``wraps'' them all.

@findex longlines-auto-wrap
  The word wrap performed by Long Lines mode is @emph{not} the same as
ordinary filling (@pxref{Fill Commands}).  It does not contract
multiple spaces into a single space, recognize fill prefixes
(@pxref{Fill Prefix}), or perform adaptive filling (@pxref{Adaptive
Fill}).  The reason for this is that a wrapped line is still,
conceptually, a single line.  Each soft newline is equivalent to
exactly one space in that long line, and vice versa.  However, you can
still call filling functions such as @kbd{M-q}, and these will work as
expected, inserting soft newlines that won't show up on disk or when
the text is copied.  You can even rely entirely on the normal fill
commands by turning off automatic line wrapping, with @kbd{C-u M-x
longlines-auto-wrap}.  To turn automatic line wrapping back on, type
@kbd{M-x longlines-auto-wrap}.

@findex longlines-show-hard-newlines
  Type @kbd{RET} to insert a hard newline, one which automatic
refilling will not remove.  If you want to see where all the hard
newlines are, type @kbd{M-x longlines-show-hard-newlines}.  This will
mark each hard newline with a special symbol.  The same command with a
prefix argument turns this display off.

  Long Lines mode does not change normal text files that are already
filled, since the existing newlines are considered hard newlines.
Before Long Lines can do anything, you need to transform each
paragraph into a long line.  One way is to set @code{fill-column} to a
large number (e.g., @kbd{C-u 9999 C-x f}), re-fill all the paragraphs,
and then set @code{fill-column} back to its original value.

@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
  The word conversion commands are the most useful.  @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

  When you edit files of text in a human language, it's more convenient
to use Text mode rather than Fundamental mode.  To enter 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)}
  Text mode defines @key{TAB} to run @code{indent-relative}
(@pxref{Indentation}), so that you can conveniently indent a line like
the previous line.

  Text mode turns off the features concerned with comments except when
you explicitly invoke them.  It changes the syntax table so that
single-quotes are considered part of words.  However, if a word starts
with single-quotes, these are treated as a prefix for purposes such as
capitalization.  That is, @kbd{M-c} will convert @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 rather than Text mode.  In this 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-text-mode} to enter this mode.  Use @kbd{M-x
paragraph-indent-minor-mode} to enable an equivalent minor mode in
situations where you can't change the major mode---in mail
composition, for instance.

@kindex M-TAB @r{(Text mode)}
  Text mode, and all the modes based on it, define @kbd{M-@key{TAB}}
as the command @code{ispell-complete-word}, which 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}.

@vindex text-mode-hook
  Entering Text mode runs the hook @code{text-mode-hook}.  Other major
modes related to Text mode also run this hook, followed by hooks of
their own; this includes Paragraph-Indent Text mode, Nroff mode,
@TeX{} mode, Outline mode, and Message mode.  Hook functions on
@code{text-mode-hook} can look at the value of @code{major-mode} to
see which of these modes is actually being entered.  @xref{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
  Outline mode is a major mode much like Text mode but intended for
editing outlines.  It allows you to make parts of the text temporarily
invisible so that you can see the outline structure.  Type @kbd{M-x
outline-mode} to switch to Outline mode as the major mode of the current
buffer.

  When Outline mode makes a line invisible, the line does not appear
on the screen.  The screen appears exactly as if the invisible line
were deleted, except that an ellipsis (three periods in a row) appears
at the end of the previous visible line.  (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 lines.

  Outline minor mode provides the same commands as the major mode,
Outline mode, but you can use it in conjunction with other major modes.
Type @kbd{M-x outline-minor-mode} to enable the Outline minor mode in
the current buffer.  You can also specify this in the text of a file,
with a file local variable of the form @samp{mode: outline-minor}
(@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-mode-hook
  Entering Outline mode runs the hook @code{text-mode-hook} followed by
the hook @code{outline-mode-hook} (@pxref{Hooks}).

@menu
* Format: Outline Format.          What the text of an outline looks like.
* Motion: Outline Motion.          Special commands for moving through
                                     outlines.
* Visibility: Outline Visibility.  Commands to control what is visible.
* Views: 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 stars; the
number of stars determines the depth of the heading in the outline
structure.  Thus, a heading line with one star is a major topic; all the
heading lines with two stars between it and the next one-star 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
Move point to the next visible heading line
(@code{outline-next-visible-heading}).
@item C-c C-p
Move point to the previous visible heading line
(@code{outline-previous-visible-heading}).
@item C-c C-f
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
Move point to the previous visible heading line at the same level
(@code{outline-backward-same-level}).
@item C-c C-u
Move point up to a lower-level (more inclusive) visible heading line
(@code{outline-up-heading}).
@end table

@findex outline-next-visible-heading
@findex outline-previous-visible-heading
@kindex C-c C-n @r{(Outline mode)}
@kindex C-c C-p @r{(Outline mode)}
  @kbd{C-c C-n} (@code{outline-next-visible-heading}) moves down to the next
heading line.  @kbd{C-c C-p} (@code{outline-previous-visible-heading}) moves
similarly backward.  Both accept numeric arguments as repeat counts.  The
names emphasize that invisible headings are skipped, but this is not really
a special feature.  All editing commands that look for lines ignore the
invisible lines automatically.

@findex outline-up-heading
@findex outline-forward-same-level
@findex outline-backward-same-level
@kindex C-c C-f @r{(Outline mode)}
@kindex C-c C-b @r{(Outline mode)}
@kindex C-c C-u @r{(Outline mode)}
  More powerful motion commands understand the level structure of headings.
@kbd{C-c C-f} (@code{outline-forward-same-level}) and
@kbd{C-c C-b} (@code{outline-backward-same-level}) move from one
heading line to another visible heading at the same depth in
the outline.  @kbd{C-c C-u} (@code{outline-up-heading}) moves
backward to another heading that is less deeply nested.

@node Outline Visibility
@subsection Outline Visibility Commands

  The other special commands of outline mode are used to make lines visible
or invisible.  Their names all start with @code{hide} or @code{show}.
Most of them fall into pairs of opposites.  They are not undoable; instead,
you can undo right past them.  Making lines visible or invisible is simply
not recorded by the undo mechanism.

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

@findex hide-entry
@findex show-entry
@kindex C-c C-c @r{(Outline mode)}
@kindex C-c C-e @r{(Outline mode)}
  Two commands that are exact opposites are @kbd{C-c C-c}
(@code{hide-entry}) and @kbd{C-c C-e} (@code{show-entry}).  They apply
to the body lines directly following the current heading line.
Subheadings and their bodies are not affected.

@findex hide-subtree
@findex show-subtree
@kindex C-c C-s @r{(Outline mode)}
@kindex C-c C-d @r{(Outline mode)}
@cindex subtree (Outline mode)
  Two more powerful opposites are @kbd{C-c C-d} (@code{hide-subtree})
and @kbd{C-c C-s} (@code{show-subtree}).  Both apply to the current
heading line's @dfn{subtree}: its body, all its subheadings, both
direct and indirect, and all of their bodies.  In other words, the
subtree contains everything following the current heading line, up to
and not including the next heading of the same or higher rank.

@findex hide-leaves
@findex show-branches
@kindex C-c C-l @r{(Outline mode)}
@kindex C-c C-k @r{(Outline mode)}
  Intermediate between a visible subtree and an invisible one is having
all the subheadings visible but none of the body.  There are two
commands for doing this, depending on whether you want to hide the
bodies or make the subheadings visible.  They are @kbd{C-c C-l}
(@code{hide-leaves}) and @kbd{C-c C-k} (@code{show-branches}).

@kindex C-c C-i @r{(Outline mode)}
@findex show-children
  A little weaker than @code{show-branches} is @kbd{C-c C-i}
(@code{show-children}).  It makes just the direct subheadings
visible---those one level down.  Deeper subheadings remain invisible, if
they were invisible.

@findex hide-body
@findex show-all
@kindex C-c C-t @r{(Outline mode)}
@kindex C-c C-a @r{(Outline mode)}
  Two commands have a blanket effect on the whole file.  @kbd{C-c C-t}
(@code{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{show-all})
makes all lines visible.  These commands can be thought of as a pair
of opposites even though @kbd{C-c C-a} applies to more than just body
lines.

@findex hide-sublevels
@kindex C-c C-q @r{(Outline mode)}
  The command @kbd{C-c C-q} (@code{hide-sublevels}) hides all but the
top level headings.  With a numeric argument @var{n}, it hides everything
except the top @var{n} levels of heading lines.

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

@findex reveal-mode
  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.  You can also
automatically make text visible as you navigate in it by using
@kbd{M-x reveal-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 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 show-children}), e.g.@: @kbd{M-2
C-c C-z} exposes two levels of child subheadings.  Alternatively, the
body can be specified with a negative argument: @kbd{M-- C-c C-z}.  The
whole subtree can be expanded, similarly to @kbd{C-c C-s} (@kbd{M-x
show-subtree}), by specifying a zero argument: @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, @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

@vindex foldout-mouse-modifiers
  You can specify different modifier keys (instead of
@kbd{Control-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 this in your @file{.emacs} file:

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

@node TeX Mode
@section @TeX{} Mode
@cindex @TeX{} mode
@cindex La@TeX{} mode
@cindex Sli@TeX{} mode
@cindex Doc@TeX{} mode
@cindex mode, @TeX{}
@cindex mode, La@TeX{}
@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

  Emacs provides special major modes for editing files written in
@TeX{} and its related formats.  @TeX{} is a powerful text formatter
written by Donald Knuth; like GNU Emacs, it is free software.
La@TeX{} is a simplified input format for @TeX{}, implemented using
@TeX{} macros.  Doc@TeX{} is a special file format in which the
La@TeX{} sources are written, combining sources with documentation.
Sli@TeX{} is an obsolete special form of La@TeX{}.@footnote{It has
been replaced by the @samp{slides} document class, which comes with
La@TeX{}.}

@vindex tex-default-mode
  @TeX{} mode has four variants: Plain @TeX{} mode, La@TeX{} mode,
Doc@TeX{} mode, and Sli@TeX{} mode.  These distinct major modes differ
only slightly, and are designed for editing the four different
formats.  Emacs selects the appropriate mode by looking at the
contents of the buffer.  (This is done by 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 command @kbd{M-x plain-tex-mode}, @kbd{M-x
latex-mode}, @kbd{M-x slitex-mode}, or @kbd{doctex-mode}.

  Emacs also provides Bib@TeX{} mode, a major mode for editing
Bib@TeX{} files.  Bib@TeX{} is a tool for storing and formatting
bibliographic references, which is commonly used together with
La@TeX{}.  In addition, the Ref@TeX{} package provides a minor mode
which can be used in conjunction with La@TeX{} mode to manage
bibliographic references.  @inforef{Top,, reftex}.

@menu
* Editing: TeX Editing.   Special commands for editing in TeX mode.
* LaTeX: LaTeX Editing.   Additional commands for LaTeX input files.
* Printing: TeX Print.    Commands for printing part of a file with TeX.
* Misc: 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{''}.  For
convenience, @TeX{} mode overrides the normal meaning of the key
@kbd{"} with a command that inserts a pair of single-quotes or
backquotes (@code{tex-insert-quote}).  To be precise, it 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.)

  To disable the @kbd{"} expansion feature, eliminate that binding in
the local map (@pxref{Key Bindings}).

  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.

@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 the
@samp{*Occur*} buffer, and you can use @kbd{C-c C-c} or @kbd{Mouse-2} in
that buffer to go to a particular mismatch.

  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 La@TeX{} Editing Commands

  La@TeX{} mode (and its obsolete variant, Sli@TeX{} mode) provide a
few extra features not applicable to plain @TeX{}:

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

@findex tex-latex-block
@kindex C-c C-o @r{(La@TeX{} mode)}
@vindex latex-block-names
  In La@TeX{} input, @samp{\begin} and @samp{\end} commands are used to
group blocks of text.  To insert a @samp{\begin} and a matching
@samp{\end} (on a new line following the @samp{\begin}), use @kbd{C-c
C-o} (@code{tex-latex-block}).  A blank line is inserted between the
two, and point is left there.  You can use completion when you enter the
block type; to specify additional block type names beyond the standard
list, set the variable @code{latex-block-names}.  For example, here's
how to add @samp{theorem}, @samp{corollary}, and @samp{proof}:

@example
(setq latex-block-names '("theorem" "corollary" "proof"))
@end example

@findex tex-close-latex-block
@kindex C-c C-e @r{(La@TeX{} mode)}
  In La@TeX{} input, @samp{\begin} and @samp{\end} commands must
balance.  You can use @kbd{C-c C-e} (@code{tex-close-latex-block}) to
insert automatically a matching @samp{\end} to match the last unmatched
@samp{\begin}.  It indents the @samp{\end} to match the corresponding
@samp{\begin}.  It inserts a newline after @samp{\end} if point is at
the beginning of a line.

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

  You can invoke @TeX{} as an inferior of Emacs on either the entire
contents of the buffer or just a region at a time.  Running @TeX{} in
this way on just one chapter is a good way to see what your changes
look like without taking the time to format the entire file.

@table @kbd
@item C-c C-r
Invoke @TeX{} on the current region, together with the buffer's header
(@code{tex-region}).
@item C-c C-b
Invoke @TeX{} on the entire current buffer (@code{tex-buffer}).
@item C-c @key{TAB}
Invoke Bib@TeX{} on the current file (@code{tex-bibtex-file}).
@item C-c C-f
Invoke @TeX{} on the current file (@code{tex-file}).
@item C-c C-l
Recenter the window showing output from the inferior @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-p
Print the output from the last @kbd{C-c C-r}, @kbd{C-c C-b}, or @kbd{C-c
C-f} command (@code{tex-print}).
@item C-c C-v
Preview the output from the last @kbd{C-c C-r}, @kbd{C-c C-b}, or @kbd{C-c
C-f} command (@code{tex-view}).
@item C-c C-q
Show the printer queue (@code{tex-show-print-queue}).
@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-print
@kindex C-c C-p @r{(@TeX{} mode)}
@findex tex-view
@kindex C-c C-v @r{(@TeX{} mode)}
@findex tex-show-print-queue
@kindex C-c C-q @r{(@TeX{} mode)}
  You can pass the current buffer through an inferior @TeX{} by means of
@kbd{C-c C-b} (@code{tex-buffer}).  The formatted output appears in a
temporary file; to print it, type @kbd{C-c C-p} (@code{tex-print}).
Afterward, you can use @kbd{C-c C-q} (@code{tex-show-print-queue}) to
view the progress of your output towards being printed.  If your terminal
has the ability to display @TeX{} output files, you can preview the
output on the terminal with @kbd{C-c C-v} (@code{tex-view}).

@cindex @env{TEXINPUTS} environment variable
@vindex tex-directory
  You can specify the directory to use for running @TeX{} by setting the
variable @code{tex-directory}.  @code{"."} is the default value.  If
your environment variable @env{TEXINPUTS} contains relative directory
names, or if your files contains @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 slitex-run-command
@vindex tex-dvi-print-command
@vindex tex-dvi-view-command
@vindex tex-show-queue-command
  If you want to specify which shell commands are used in the inferior @TeX{},
you can do so by setting the values of the variables @code{tex-run-command},
@code{latex-run-command}, @code{slitex-run-command},
@code{tex-dvi-print-command}, @code{tex-dvi-view-command}, and
@code{tex-show-queue-command}.  The default values may
(or may not) be appropriate for your system.

  Normally, the file name given to these commands comes at the end of
the command string; for example, @samp{latex @var{filename}}.  In some
cases, however, the file name needs to be embedded in the command; an
example is when 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 @samp{*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 an inferior @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 La@TeX{} mode, the header begins with @samp{\documentclass} or
@samp{\documentstyle} and ends with @samp{\begin@{document@}}.  These
are commands that La@TeX{} 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 La@TeX{} 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 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{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.
@ignore
@c Too cryptic to be useful, too cryptic for me to make it better -- rms.
  They
are included by default in the @code{format-alist} variable, so they
can be used with @kbd{M-x format-find-file}, for instance.
@end ignore

@ignore  @c Not worth documenting if it is only for Czech -- rms.
@findex tildify-buffer
@findex tildify-region
@cindex ties, @TeX{}, inserting
@cindex hard spaces, @TeX{}, inserting
  The commands @kbd{M-x tildify-buffer} and @kbd{M-x tildify-region}
insert @samp{~} (@dfn{tie}) characters where they are conventionally
required.  This is set up for Czech---customize the group
@samp{tildify} for other languages or for other sorts of markup.
@end ignore

@cindex Ref@TeX{} package
@cindex references, La@TeX{}
@cindex La@TeX{} references
  For managing all kinds of references for La@TeX{}, you can use
Ref@TeX{}.  @inforef{Top,, reftex}.

@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 mode is a slightly customized
variant of SGML mode.

@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 from within a tag or a comment,
close this element 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}).

@item C-c 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
@findex nxml-mode
@cindex XML schema
  The default mode for editing XML documents is called nXML mode
(@code{xml-mode} or @code{nxml-mode}).  This is a powerful major mode
that can recognize many existing XML schema and use them to provide
completion of XML elements via @kbd{C-@key{RET}} or @kbd{M-@key{TAB}},
as well as ``on-the-fly'' XML validation with error highlighting.  It
is described in its own manual.  @xref{Top, nXML Mode,,nxml-mode, nXML
Mode}.

@vindex sgml-xml-mode
  However, you can also use SGML mode to edit XML, since XML is a
strict subset of SGML.  In XML, every opening tag must have an
explicit closing tag.  When the variable @code{sgml-xml-mode} is
non-@code{nil}, the tag insertion commands described above always
insert explicit closing tags as well.  When you visit a file in SGML
mode, Emacs determines whether it is XML by examining the file
contents, and sets @code{sgml-xml-mode} accordingly.

@node Nroff Mode
@section Nroff Mode

@cindex nroff
@findex nroff-mode
  Nroff mode is a mode like Text mode but modified to handle nroff commands
present in the text.  Invoke @kbd{M-x nroff-mode} to enter this mode.  It
differs from Text mode in only a few ways.  All nroff command lines are
considered paragraph separators, so that filling will never garble the
nroff commands.  Pages are separated by @samp{.bp} commands.  Comments
start with backslash-doublequote.  Also, three special commands are
provided that are not in Text mode:

@findex forward-text-line
@findex backward-text-line
@findex 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{forward-text-line}).  An argument is a repeat count.
@item M-p
Like @kbd{M-n} but move up (@code{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{count-text-lines}).
@end table

@findex electric-nroff-mode
  The other feature of Nroff mode is that you can turn on Electric Nroff
mode.  This is a minor mode that you can turn on or off with @kbd{M-x
electric-nroff-mode} (@pxref{Minor Modes}).  When the mode is on, each
time you use @key{RET} to end a line that contains an nroff command that
opens a kind of grouping, the matching nroff command to close that
grouping is automatically inserted on the following line.  For example,
if you are at the beginning of a line and type @kbd{.@: ( b @key{RET}},
this inserts the matching command @samp{.)b} on a new line following
point.

  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).

@vindex nroff-mode-hook
  Entering Nroff mode runs the hook @code{text-mode-hook}, followed by
the hook @code{nroff-mode-hook} (@pxref{Hooks}).

@node Formatted Text
@section Editing Formatted Text

@cindex Enriched mode
@cindex mode, Enriched
@cindex formatted text
@cindex WYSIWYG
@cindex word processing
  @dfn{Enriched mode} is a minor mode for editing files that contain
formatted text in WYSIWYG fashion, as in a word processor.  Currently,
formatted text in Enriched mode can specify fonts, colors, underlining,
margins, and types of filling and justification.  In the future, we plan
to implement other formatting features as well.

  Enriched mode is a minor mode (@pxref{Minor Modes}).  It is
typically used in conjunction with Text mode (@pxref{Text Mode}), but
you can also use it with other major modes such as Outline mode and
Paragraph-Indent Text mode.

@cindex text/enriched MIME format
  Potentially, Emacs can store formatted text files in various file
formats.  Currently, only one format is implemented: @dfn{text/enriched}
format, which is defined by the MIME protocol.  @xref{Format
Conversion,, Format Conversion, elisp, the Emacs Lisp Reference Manual},
for details of how Emacs recognizes and converts file formats.

  The Emacs distribution contains a formatted text file that can serve as
an example.  Its name is @file{etc/enriched.doc}.  It contains samples
illustrating all the features described in this section.  It also
contains a list of ideas for future enhancements.

@menu
* Requesting Formatted Text::   Entering and exiting Enriched mode.
* Hard and Soft Newlines::      There are two different kinds of newlines.
* Editing Format Info::         How to edit text properties.
* Faces: Format Faces.          Bold, italic, underline, etc.
* Color: Format Colors.         Changing the color of text.
* Indent: Format Indentation.   Changing the left and right margins.
* Justification: Format Justification.
                                Centering, setting text flush with the
                                  left or right margin, etc.
* Special: Format Properties.   The "special" text properties submenu.
* Forcing Enriched Mode::       How to force use of Enriched mode.
@end menu

@node Requesting Formatted Text
@subsection Requesting to Edit Formatted Text

  Whenever you visit a file that Emacs saved in the text/enriched
format, Emacs automatically converts the formatting information in the
file into Emacs's own internal format (known as @dfn{text
properties}), and turns on Enriched mode.

@findex enriched-mode
  To create a new file of formatted text, first visit the nonexistent
file, then type @kbd{M-x enriched-mode} before you start inserting text.
This command turns on Enriched mode.  Do this before you begin inserting
text, to ensure that the text you insert is handled properly.

  More generally, the command @code{enriched-mode} turns Enriched mode
on if it was off, and off if it was on.  With a prefix argument, this
command turns Enriched mode on if the argument is positive, and turns
the mode off otherwise.

  When you save a buffer while Enriched mode is enabled in it, Emacs
automatically converts the text to text/enriched format while writing it
into the file.  When you visit the file again, Emacs will automatically
recognize the format, reconvert the text, and turn on Enriched mode
again.

@vindex enriched-translations
  You can add annotations for saving additional text properties, which
Emacs normally does not save, by adding to @code{enriched-translations}.
Note that the text/enriched standard requires any non-standard
annotations to have names starting with @samp{x-}, as in
@samp{x-read-only}.  This ensures that they will not conflict with
standard annotations that may be added later.

  @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

@cindex use-hard-newlines
  In formatted text, Emacs distinguishes between two different kinds of
newlines, @dfn{hard} newlines and @dfn{soft} newlines.  (You can enable
or disable this feature separately in any  buffer with the command
@code{use-hard-newlines}.)

  Hard newlines are used to separate paragraphs, or items in a list, or
anywhere that there should always be a line break regardless of the
margins.  The @key{RET} command (@code{newline}) and @kbd{C-o}
(@code{open-line}) insert hard newlines.

  Soft newlines are used to make text fit between the margins.  All the
fill commands, including Auto Fill, insert soft newlines---and they
delete only soft newlines.

  Although hard and soft newlines look the same, it is important to bear
the difference in mind.  Do not use @key{RET} to break lines in the
middle of filled paragraphs, or else you will get hard newlines that are
barriers to further filling.  Instead, let Auto Fill mode break lines,
so that if the text or the margins change, Emacs can refill the lines
properly.  @xref{Auto Fill}.

  On the other hand, in tables and lists, where the lines should always
remain as you type them, you can use @key{RET} to end lines.  For these
lines, you may also want to set the justification style to
@code{unfilled}.  @xref{Format Justification}.

@node Editing Format Info
@subsection Editing Format Information

  There are two ways to alter the formatting information for a formatted
text file: with keyboard commands, and with the mouse.

  The easiest way to add properties to your document is with the Text
Properties menu.  You can get to this menu in two ways: from the Edit
menu in the menu bar (use @kbd{@key{F10} e t} if you have no mouse),
or with @kbd{C-Mouse-2} (hold the @key{CTRL} key and press the middle
mouse button).  There are also keyboard commands described in the
following section.

  These items in the Text Properties menu run commands directly:

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

@findex facemenu-remove-all
@item Remove Text Properties
Delete @emph{all} text properties from the region
(@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 the text properties, widgets, buttons, and overlays of the
character following point (@code{describe-text-properties}).

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

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

@ifinfo
  Other items in the Text Properties menu lead to submenus:

@menu
* Faces: Format Faces.          Bold, italic, underline, etc.
* Color: Format Colors.         Changing the color of text.
* Indent: Format Indentation.   Changing the left and right margins.
* Justification: Format Justification.
                                Centering, setting text flush with the
                                  left or right margin, etc.
* Special: Format Properties.   The "special" text properties submenu.
@end menu
@end ifinfo
@ifnotinfo
  The rest lead to submenus which are described in the following sections.
@end ifnotinfo

@node Format Faces
@subsection Faces in Formatted Text

  The Faces submenu under Text Properties lists various Emacs faces
including @code{bold}, @code{italic}, and @code{underline}
(@pxref{Faces}).  These menu items operate on the region if it is
active and nonempty.  Otherwise, they specify to use that face for an
immediately following self-inserting character.  There is also an item
@samp{Other} with which you can enter a face name through the
minibuffer (@pxref{Standard Faces}).

  Instead of the Faces submenu, you can use these keyboard commands:

@table @kbd
@kindex M-o d @r{(Enriched mode)}
@findex facemenu-set-default
@item M-o d
Remove all @code{face} properties from the region (which includes
specified colors), or force the following inserted character to have no
@code{face} property (@code{facemenu-set-default}).
@kindex M-o b @r{(Enriched mode)}
@findex facemenu-set-bold
@item M-o b
Add the face @code{bold} to the region or to the following inserted
character (@code{facemenu-set-bold}).
@kindex M-o i @r{(Enriched mode)}
@findex facemenu-set-italic
@item M-o i
Add the face @code{italic} to the region or to the following inserted
character (@code{facemenu-set-italic}).
@kindex M-o l @r{(Enriched mode)}
@findex facemenu-set-bold-italic
@item M-o l
Add the face @code{bold-italic} to the region or to the following
inserted character (@code{facemenu-set-bold-italic}).
@kindex M-o u @r{(Enriched mode)}
@findex facemenu-set-underline
@item M-o u
Add the face @code{underline} to the region or to the following inserted
character (@code{facemenu-set-underline}).
@kindex M-o o @r{(Enriched mode)}
@findex facemenu-set-face
@item M-o o @var{face} @key{RET}
Add the face @var{face} to the region or to the following inserted
character (@code{facemenu-set-face}).
@end table

   With a prefix argument, all these commands apply to an immediately
following self-inserting character, disregarding the region.

  A self-inserting character normally inherits the @code{face}
property (and most other text properties) from the preceding character
in the buffer.  If you use the above commands to specify face for the
next self-inserting character, or the next section's commands to
specify a foreground or background color for it, then it does not
inherit the @code{face} property from the preceding character; instead
it uses whatever you specified.  It will still inherit other text
properties, though.

  Strictly speaking, these commands apply only to the first following
self-inserting character that you type.  But if you insert additional
characters after it, they will inherit from the first one.  So it
appears that these commands apply to all of them.

  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.  This face is the
same as @code{italic} unless you customize it (@pxref{Face Customization}).

  The @code{fixed} face means, ``Use a fixed-width font for this part
of the text.''  Applying the @code{fixed} face to a part of the text
will cause that part of the text to appear in a fixed-width font, even
if the default font is variable-width.  This applies to Emacs and to
other systems that display text/enriched format.  So if you
specifically want a certain part of the text to use a fixed-width
font, you should specify the @code{fixed} face for that part.

  By default, the @code{fixed} face looks the same as @code{bold}.
This is an attempt to distinguish it from @code{default}.  You may
wish to customize @code{fixed} to some other fixed-width medium font.
@xref{Face Customization}.

  If your terminal cannot display different faces, you will not be
able to see them, but you can still edit documents containing faces,
and even add faces and colors to documents.  The faces you specify
will be visible when the file is viewed on a terminal that can display
them.

@node Format Colors
@subsection Colors in Formatted Text

  You can specify foreground and background colors for portions of the
text.  Under Text Properties, there is a submenu for specifying the
foreground color, and a submenu for specifying the background color.
Each one lists all the colors that you have used in Enriched mode in
the current Emacs session.

  If the region is active, the command applies to the text in the
region; otherwise, it applies to any immediately following
self-inserting input.  When Transient Mark mode is off
(@pxref{Persistent Mark}), it always applies to the region unless a
prefix argument is given, in which case it applies to the following
input.

  Each of the two color submenus contains one additional item:
@samp{Other}.  You can use this item to specify a color that is not
listed in the menu; it reads the color name with the minibuffer.  To
display a list of available colors and their names, use the
@samp{Display Colors} menu item in the Text Properties menu
(@pxref{Editing Format Info}).

  Any color that you specify in this way, or that is mentioned in a
formatted text file that you read in, is added to the corresponding
color menu for the duration of the Emacs session.

@findex facemenu-set-foreground
@findex facemenu-set-background
  There are no predefined key bindings for specifying colors, but you can do so
with the extended commands @kbd{M-x facemenu-set-foreground} and
@kbd{M-x facemenu-set-background}.  Both of these commands read the name
of the color with the minibuffer.

@node Format Indentation
@subsection Indentation in Formatted Text

  When editing formatted text, you can specify different amounts of
indentation for the right or left margin of an entire paragraph or a
part of a paragraph.  The margins you specify automatically affect the
Emacs fill commands (@pxref{Filling}) and line-breaking commands.

  The Indentation submenu of Text Properties provides a convenient
interface for specifying these properties.  The submenu contains four
items:

@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

  You can use these commands repeatedly to increase or decrease the
indentation.

  The most common way to use them is to change the indentation of an
entire paragraph.  For other uses, the effects of refilling can be
hard to predict, except in some special cases like the one described
next.

  The most common other use is to format paragraphs with @dfn{hanging
indents}, which means that the first line is indented less than
subsequent lines.  To set up a hanging indent, increase the
indentation of the region starting after the first word of the
paragraph and running until the end of the paragraph.

  Indenting the first line of a paragraph is easier.  Set the margin for
the whole paragraph where you want it to be for the body of the
paragraph, then indent the first line by inserting extra spaces or tabs.

@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 overall 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
  There are also two commands for setting the left or right margin of
the region absolutely: @code{set-left-margin} and
@code{set-right-margin}.  Enriched mode binds these commands to
@kbd{C-c [} and @kbd{C-c ]}, respectively.  You can specify the
margin width either with a numeric argument or in the minibuffer.

  Sometimes, as a result of editing, the filling of a paragraph becomes
messed up---parts of the paragraph may extend past the left or right
margins.  When this happens, use @kbd{M-q} (@code{fill-paragraph}) to
refill the paragraph.

  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 Format Justification
@subsection Justification in Formatted Text

  When editing formatted text, you can specify various styles of
justification for a paragraph.  The style you specify automatically
affects the Emacs fill commands.

  The Justification submenu of Text Properties provides a convenient
interface for specifying the style.  The submenu contains five items:

@table @code
@item Left
This is the most common style of justification (at least for English).
Lines are aligned at the left margin but left uneven at the right.

@item Right
This aligns each line with the right margin.  Spaces and tabs are added
on the left, if necessary, to make lines line up on the right.

@item Full
This justifies the text, aligning both edges of each line.  Justified
text looks very nice in a printed book, where the spaces can all be
adjusted equally, but it does not look as nice with a fixed-width font
on the screen.  Perhaps a future version of Emacs will be able to adjust
the width of spaces in a line to achieve elegant justification.

@item Center
This centers every line between the current margins.

@item Unfilled
This turns off filling entirely.  Each line will remain as you wrote it;
the fill and auto-fill functions will have no effect on text which has
this setting.  You can, however, still indent the left margin.  In
unfilled regions, all newlines are treated as hard newlines (@pxref{Hard
and Soft Newlines}) .
@end table

  In Enriched mode, you can also specify justification from the keyboard
using the @kbd{M-j} prefix character:

@table @kbd
@kindex M-j l @r{(Enriched mode)}
@findex set-justification-left
@item M-j l
Make the region left-filled (@code{set-justification-left}).
@kindex M-j r @r{(Enriched mode)}
@findex set-justification-right
@item M-j r
Make the region right-filled (@code{set-justification-right}).
@kindex M-j b @r{(Enriched mode)}
@findex set-justification-full
@item M-j b
Make the region fully justified (@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
Make the region centered (@code{set-justification-center}).
@kindex M-j u @r{(Enriched mode)}
@findex set-justification-none
@item M-j u
Make the region unfilled (@code{set-justification-none}).
@end table

  Justification styles apply to entire paragraphs.  All the
justification-changing commands operate on the paragraph containing
point, or, if the region is active, on all paragraphs which overlap the
region.

@vindex default-justification
  The default justification style is specified by the variable
@code{default-justification}.  Its value should be one of the symbols
@code{left}, @code{right}, @code{full}, @code{center}, or @code{none}.
This is a per-buffer variable.  Setting the variable directly affects
only the current buffer.  However, customizing it in a Custom buffer
sets (as always) the default value for buffers that do not override it.
@xref{Locals}, and @ref{Easy Customization}.

@node Format Properties
@subsection Setting Other Text Properties

  The Special Properties submenu of Text Properties can add or remove
three other useful text properties: @code{read-only}, @code{invisible}
and @code{intangible}.  The @code{intangible} property disallows
moving point within the text, the @code{invisible} text property hides
text from display, and the @code{read-only} property disallows
alteration of the text.

  Each of these special properties has a menu item to add it to the
region.  The last menu item, @samp{Remove Special}, removes all of these
special properties from the text in the region.

  Currently, the @code{invisible} and @code{intangible} properties are
@emph{not} saved in the text/enriched format.  The @code{read-only}
property is saved, but it is not a standard part of the text/enriched
format, so other editors may not respect it.

@node Forcing Enriched Mode
@subsection Forcing Enriched Mode

  Normally, Emacs knows when you are editing formatted text because it
recognizes the special annotations used in the file that you visited.
However, sometimes you must take special actions to convert file
contents or turn on Enriched mode:

@itemize @bullet
@item
When you visit a file that was created with some other editor, Emacs may
not recognize the file as being in the text/enriched format.  In this
case, when you visit the file you will see the formatting commands
rather than the formatted text.  Type @kbd{M-x format-decode-buffer} to
translate it.  This also automatically turns on Enriched mode.

@item
When you @emph{insert} a file into a buffer, rather than visiting it,
Emacs does the necessary conversions on the text which you insert, but
it does not enable Enriched mode.  If you wish to do that, type @kbd{M-x
enriched-mode}.
@end itemize

  The command @code{format-decode-buffer} translates text in various
formats into Emacs's internal format.  It asks you to specify the format
to translate from; however, normally you can type just @key{RET}, which
tells Emacs to guess the format.

@findex format-find-file
  If you wish to look at a text/enriched file in its raw form, as a
sequence of characters rather than as formatted text, use the @kbd{M-x
find-file-literally} command.  This visits a file, like
@code{find-file}, but does not do format conversion.  It also inhibits
character code conversion (@pxref{Coding Systems}) and automatic
uncompression (@pxref{Compressed Files}).  To disable format conversion
but allow character code conversion and/or automatic uncompression if
appropriate, use @code{format-find-file} with suitable arguments.

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

  Table mode provides an easy and intuitive way to create and edit WYSIWYG
text-based tables.  Here is an example of such a table:

@smallexample
@group
+-----------------+--------------------------------+-----------------+
|     Command     |          Description           |   Key Binding   |
+-----------------+--------------------------------+-----------------+
|  forward-char   |Move point right N characters   |       C-f       |
|                 |(left if N is negative).        |                 |
|                 |                                |                 |
|                 |On reaching end of buffer, stop |                 |
|                 |and signal error.               |                 |
+-----------------+--------------------------------+-----------------+
|  backward-char  |Move point left N characters    |       C-b       |
|                 |(right if N is negative).       |                 |
|                 |                                |                 |
|                 |On attempt to pass beginning or |                 |
|                 |end of buffer, stop and signal  |                 |
|                 |error.                          |                 |
+-----------------+--------------------------------+-----------------+
@end group
@end smallexample

  Table mode allows the contents of the table such as this one to be
easily manipulated by inserting or deleting characters inside a cell.
A cell is effectively a localized rectangular edit region and edits to
a cell do not affect the contents of the surrounding cells.  If the
contents do not fit into a cell, then the cell is automatically
expanded in the vertical and/or horizontal directions and the rest of
the table is restructured and reformatted in accordance with the
growth of the cell.

@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.
* Row Commands::              Manipulating rows of table cell.
* Column Commands::           Manipulating columns of table cell.
* Fixed Width Mode::          Fixing cell width.
* Table Conversion::          Converting between plain text and tables.
* Measuring Tables::          Analyzing table dimension.
* Table Misc::                Table miscellany.
@end menu

@node Table Definition
@subsection What is a Text-based Table?

  Keep the following examples of valid tables in mind as a reference
while you read this section:

@example
              +--+----+---+     +-+     +--+-----+
              |  |    |   |     | |     |  |     |
              +--+----+---+     +-+     |  +--+--+
              |  |    |   |             |  |  |  |
              +--+----+---+             +--+--+  |
                                        |     |  |
                                        +-----+--+
@end example

  A table consists of a rectangular frame whose inside is divided into
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 multiple rectangular cells, but cells cannot overlap.

  The table frame and cell border lines are made of three special
characters.  These variables specify those characters:

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

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

@vindex table-cell-intersection-char
@item table-cell-intersection-char
Holds the character used at where horizontal line and vertical line
meet.  The default value is @samp{+}.
@end table

@noindent
Based on this definition, the following five tables are examples of invalid
tables:

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

From left to right:

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

@node Table Creation
@subsection How to Create a Table?
@cindex create a text-based table
@cindex table creation

@findex table-insert
  The command to create a table is @code{table-insert}.  When called
interactively, it asks for the number of columns, number of rows, cell
width and cell height.  The number of columns is the number of cells
horizontally side by side.  The number of rows is the number of cells
vertically within the table's height.  The cell width is a number of
characters that each cell holds, left to right.  The cell height is a
number of lines each cell holds.  The cell width and the cell height
can be either an integer (when the value is constant across the table)
or a series of integer, separated by spaces or commas, where each
number corresponds to the next cell within a row from left to right,
or the next cell within a column from top to bottom.

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

@findex table-recognize
@findex table-unrecognize
  Table mode maintains special text properties in the buffer to allow
editing in a convenient fashion.  When a buffer with tables is saved
to its file, these text properties are lost, so when you visit this
file again later, Emacs does not see a table, but just formatted text.
To resurrect the table text properties, issue the @kbd{M-x
table-recognize} command.  It scans the current buffer, recognizes
valid table cells, and attaches appropriate text properties to allow
for table editing.  The converse command, @code{table-unrecognize}, is
used to remove the special text properties and convert the buffer back
to plain text.

  Special commands exist to enable or disable tables within a region,
enable or disable individual tables, and enable/disable individual
cells.  These commands are:

@table @kbd
@findex table-recognize-region
@item M-x table-recognize-region
Recognize tables within the current region and activate them.
@findex table-unrecognize-region
@item M-x table-unrecognize-region
Deactivate tables within the current region.
@findex table-recognize-table
@item M-x table-recognize-table
Recognize the table under point and activate it.
@findex table-unrecognize-table
@item M-x table-unrecognize-table
Deactivate the table under point.
@findex table-recognize-cell
@item M-x table-recognize-cell
Recognize the cell under point and activate it.
@findex table-unrecognize-cell
@item M-x table-unrecognize-cell
Deactivate the cell under point.
@end table

  For another way of converting text into tables, see @ref{Table
Conversion}.

@node Cell Commands
@subsection Commands for Table Cells

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

@findex table-span-cell
  The command @code{table-span-cell} merges the current cell with the
adjacent cell in a specified direction---right, left, above or below.
You specify the direction with the minibuffer.  It does not allow
merges which don't result in a legitimate cell layout.

@findex table-split-cell
@cindex text-based tables, split a cell
@cindex split table cell
  The command @code{table-split-cell} splits the current cell
vertically or horizontally.  This command is a wrapper to the
direction specific commands @code{table-split-cell-vertically} and
@code{table-split-cell-horizontally}.  You specify the direction with
a minibuffer argument.

@findex table-split-cell-vertically
  The command @code{table-split-cell-vertically} splits the current
cell vertically and creates a pair of cells above and below where
point is located.  The content in the original cell is split as well.

@findex table-split-cell-horizontally
  The command @code{table-split-cell-horizontally} splits the current
cell horizontally and creates a pair of cells right and left of where
point is located.  If the cell being split is not empty, this asks you
how to handle the cell contents.  The three options are: @code{split},
@code{left}, or @code{right}.  @code{split} splits the contents at
point literally, while the @code{left} and @code{right} options move
the entire contents into the left or right cell respectively.

@cindex enlarge a table cell
@cindex shrink a table cell
  The next four commands enlarge or shrink a cell.  They use numeric
arguments (@pxref{Arguments}) to specify how many columns or rows to
enlarge or shrink a particular table.

@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 cell text justification

  You can specify text justification for each cell.  The justification
is remembered independently for each cell and the subsequent editing
of cell contents is subject to the specified justification.

@findex table-justify
  The command @code{table-justify} ask you to specify what to justify:
a cell, a column, or a row.  If you select cell justification, this
command sets the justification only for the current cell.  Selecting
column or row justification sets the justification for all the cells
within a column or row respectively.  The command then ask you which
kind of justification to apply: @code{left}, @code{center},
@code{right}, @code{top}, @code{middle}, @code{bottom}, or
@code{none}.  Horizontal justification and vertical justification are
specified independently.  The options @code{left}, @code{center}, and
@code{right} specify horizontal justification while the options
@code{top}, @code{middle}, @code{bottom}, and @code{none} specify
vertical justification.  The vertical justification @code{none}
effectively removes vertical justification.  Horizontal justification
must be one of @code{left}, @code{center}, or @code{right}.

@vindex table-detect-cell-alignment
  Justification information is stored in the buffer as a part of text
property.  Therefore, this information is ephemeral and does not
survive through the loss of the buffer (closing the buffer and
revisiting the buffer erase any previous text properties).  To
countermand for this, the command @code{table-recognize} and other
recognition commands (@pxref{Table Recognition}) are equipped with a
convenience feature (turned on by default).  During table recognition,
the contents of a cell are examined to determine which justification
was originally applied to the cell and then applies this justification
to the cell.  This is a speculative algorithm and is therefore not
perfect, however, the justification is deduced correctly most of the
time.  To disable this feature, customize the variable
@code{table-detect-cell-alignment} and set it to @code{nil}.

@node Row Commands
@subsection Commands for Table Rows
@cindex table row commands

@cindex insert row in table
@findex table-insert-row
  The command @code{table-insert-row} inserts a row of cells before
the current row in a table.  The current row where point is located is
pushed down after the newly inserted row.  A numeric prefix argument
specifies the number of rows to insert.  Note that in order to insert
rows @emph{after} the last row at the bottom of a table, you must
place point below the table---that is, outside the table---prior to
invoking this command.

@cindex delete row in table
@findex table-delete-row
  The command @code{table-delete-row} deletes a row of cells at point.
A numeric prefix argument specifies the number of rows to delete.

@node Column Commands
@subsection Commands for Table Columns
@cindex table column commands

@cindex insert column in table
@findex table-insert-column
  The command @code{table-insert-column} inserts a column of cells to
the left of the current row in a table.  This pushes the current
column to the right.  To insert a column to the right side of the
rightmost column, place point to the right of the rightmost column,
which is outside of the table, prior to invoking this command.  A
numeric prefix argument specifies the number of columns to insert.

@cindex delete column in table
  A command @code{table-delete-column} deletes a column of cells at
point.  A numeric prefix argument specifies the number of columns to
delete.

@node Fixed Width Mode
@subsection Fix Width of Cells
@cindex fix width of table cells

@findex table-fixed-width-mode
  The command @code{table-fixed-width-mode} toggles fixed width mode
on and off.  When fixed width mode is turned on, editing inside a
cell never changes the cell width; when it is off, the cell width
expands automatically in order to prevent a word from being folded
into multiple lines.  By default, fixed width mode is disabled.

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

@findex table-capture
  The command @code{table-capture} captures plain text in a region and
turns it into a table.  Unlike @code{table-recognize} (@pxref{Table
Recognition}), the original text does not have a table appearance but
may hold a logical table structure.  For example, some elements
separated by known patterns form a two dimensional structure which can
be turned into a table.

  Here's an example of data that @code{table-capture} can operate on.
The numbers are horizontally separated by a comma and vertically
separated by a newline character.

@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

@noindent
The conversion uses @samp{,} for the column delimiter and newline for
a row delimiter, cells are left justified, and minimum cell width is
5.

@findex table-release
  The command @code{table-release} does the opposite of
@code{table-capture}.  It releases a table by removing the table frame
and cell borders.  This leaves the table contents as plain text.  One
of the useful applications of @code{table-capture} and
@code{table-release} is to edit a text in layout.  Look at the
following three paragraphs (the latter two are indented with header
lines):

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

Parse Cell Items  By using column delimiter regular
                  expression and raw delimiter regular
                  expression, it parses the specified text
                  area and extracts cell items from
                  non-table text and then forms a table out
                  of them.

Capture Text Area When no delimiters are specified it
                  creates a single cell table.  The text in
                  the specified region is placed in that
                  cell.
@end example

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

@c The first line's right-hand frame in the following two examples
@c sticks out to accommodate for the removal of @samp in the
@c produced output!!
@smallexample
@group
+-------------------------------------------------------------+
|table-capture is a powerful command.                         |
|Here are some things it can do:                              |
|                                                             |
|Parse Cell Items  By using column delimiter regular          |
|                  expression and raw delimiter regular       |
|                  expression, it parses the specified text   |
|                  area and extracts cell items from          |
|                  non-table text and then forms a table out  |
|                  of them.                                   |
|                                                             |
|Capture Text Area When no delimiters are specified it        |
|                  creates a single cell table.  The text in  |
|                  the specified region is placed in that     |
|                  cell.                                      |
+-------------------------------------------------------------+
@end group
@end smallexample

@noindent
By splitting the cell appropriately we now have a table consisting of
paragraphs occupying its own cell.  Each cell can now be edited
independently without affecting the layout of other cells.

@smallexample
+--------------------------------------------------------------+
|table-capture is a powerful command.                          |
|Here are some things it can do:                               |
+------------------+-------------------------------------------+
|Parse Cell Items  |By using column delimiter regular          |
|                  |expression and raw delimiter regular       |
|                  |expression, it parses the specified text   |
|                  |area and extracts cell items from          |
|                  |non-table text and then forms a table out  |
|                  |of them.                                   |
+------------------+-------------------------------------------+
|Capture Text Area |When no delimiters are specified it        |
|                  |creates a single cell table.  The text in  |
|                  |the specified region is placed in that     |
|                  |cell.                                      |
+------------------+-------------------------------------------+
@end smallexample

@noindent
By applying @code{table-release}, which does the opposite process, the
contents become once again plain text.  @code{table-release} works as
a companion command to @code{table-capture}.

@node Measuring Tables
@subsection Analyzing Table Dimensions
@cindex table dimensions

@findex table-query-dimension
  The command @code{table-query-dimension} analyzes a table structure
and reports information regarding its dimensions.  In case of the
above example table, the @code{table-query-dimension} command displays
in echo area:

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

@noindent
This indicates that the current cell is 21 character wide and 6 lines
high, the entire table is 67 characters wide and 16 lines high.  The
table has 2 columns and 3 rows.  It has a total of 5 cells, since the
first row has a spanned cell.

@node Table Misc
@subsection Table Miscellany

@cindex insert string into table cells
@findex table-insert-sequence
  The command @code{table-insert-sequence} inserts a string into each
cell.  Each string is a part of a sequence i.e.@: a series of
increasing integer numbers.

@cindex table in language format
@cindex table for HTML and LaTeX
@findex table-generate-source
  The command @code{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}, or @code{cals}), a destination
buffer where to put the result, and the table caption (a string), and
then inserts the generated table in the proper syntax into the
destination buffer.  The default destination buffer is
@code{table.@var{lang}}, where @var{lang} is the language you
specified.

@ignore
   arch-tag: 8db54ed8-2036-49ca-b0df-23811d03dc70
@end ignore