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[gnu-emacs] / man / help.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 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Help, Mark, M-x, Top
@chapter Help
@kindex Help
@cindex help
@cindex self-documentation
@findex help-command
@kindex C-h
@kindex F1

  Emacs provides extensive help features accessible through a single
character, @kbd{C-h} (or @key{F1}).  @kbd{C-h} is a prefix key that is
used for commands that display documentation.  The characters that you
can type after @kbd{C-h} are called @dfn{help options}.  One help
option is @kbd{C-h}; that is how you ask for help about using
@kbd{C-h}.  To cancel, type @kbd{C-g}.  The function key @key{F1} is
equivalent to @kbd{C-h}.

@kindex C-h C-h
@findex help-for-help
  @kbd{C-h C-h} (@code{help-for-help}) displays a list of the possible
help options, each with a brief description.  You can look at the
list, using @key{SPC} and @key{DEL} to scroll through it, then type
the help option you want.  To cancel, type @kbd{C-g}.

  @kbd{C-h} or @key{F1} means ``help'' in various other contexts as
well.  After a prefix key, it displays a list of the alternatives that
can follow the prefix key.  (A few prefix keys don't support
@kbd{C-h}, because they define other meanings for it, but they all
support @key{F1}.)

  Most help buffers use a special major mode, Help mode, which lets you
scroll conveniently with @key{SPC} and @key{DEL}.  It also offers
hyperlinks to URLs and further help regarding cross-referenced names, Info
nodes, customization buffers and the like.  @xref{Help Mode}.

@cindex searching documentation efficiently
@cindex looking for a subject in documentation
  If you are looking for a certain feature, but don't know where
exactly it is documented, and aren't sure of the name of a
related command or variable, we recommend trying these methods.  Usually
it is best to start with an apropos command, then try searching the
manual index, then finally look in the FAQ and the package keywords.

@table @kbd
@item C-h a @var{topics} @key{RET}
This searches for commands whose names match @var{topics}, which
should be a keyword, a list of keywords, or a regular expression
(@pxref{Regexps}).  This command displays all the matches in a new
buffer.  @xref{Apropos}.

@item C-h i d m emacs @key{RET} i @var{topic} @key{RET}
This looks up @var{topic} in the indices of the Emacs on-line manual.
If there are several matches, Emacs displays the first one.  You can then
press @kbd{,} to move to other matches, until you find what you are
looking for.

@item C-h i d m emacs @key{RET} s @var{topic} @key{RET}
Similar, but searches for @var{topic} (which can be a regular
expression) in the @emph{text} of the manual rather than in its
indices.

@item C-h C-f
This brings up the Emacs FAQ.  You can use the Info commands
to browse it.

@item C-h p
Finally, you can try looking up a suitable package using keywords
pertinent to the feature you need.  @xref{Library Keywords}.
@end table

@menu
* Help Summary::        Brief list of all Help commands.
* Key Help::            Asking what a key does in Emacs.
* Name Help::           Asking about a command, variable or function name.
* Apropos::             Asking what pertains to a given topic.
* Library Keywords::    Finding Lisp libraries by keywords (topics).
* Language Help::       Help relating to international language support.
* Help Mode::           Special features of Help mode and Help buffers.
* Misc Help::           Other help commands.
* Help Files::          Commands to display pre-written help files.
* Help Echo::           Help on active text and tooltips (`balloon help')
@end menu

@iftex
@node Help Summary
@end iftex
@ifnottex
@node Help Summary
@section Help Summary
@end ifnottex

  Here is a summary of the Emacs interactive help commands.
@xref{Help Files}, for other help commands that just display a
pre-written file of information.  The character that follows
@kbd{C-h} is a ``help option.''

@table @kbd
@item C-h a @var{topics} @key{RET}
Display a list of commands whose names match @var{topics}
(@code{apropos-command}; @pxref{Apropos}).
@item C-h b
Display a table of all key bindings in effect now, in this order: minor
mode bindings, major mode bindings, and global bindings
(@code{describe-bindings}).
@item C-h c @var{key}
Show the name of the command that @var{key} runs
(@code{describe-key-briefly}).  Here @kbd{c} stands for ``character.''
For more extensive information on @var{key}, use @kbd{C-h k}.
@item C-h d @var{topics} @key{RET}
Display a list of commands and variables whose documentation matches
@var{topics} (@code{apropos-documentation}).
@item C-h e
Display the @code{*Messages*} buffer
(@code{view-echo-area-messages}).
@item C-h f @var{function} @key{RET}
Display documentation on the Lisp function named @var{function}
(@code{describe-function}).  Since commands are Lisp functions,
a command name may be used.
@item C-h h
Display the @file{HELLO} file, which shows examples of various character
sets.
@item C-h i
Run Info, the program for browsing documentation files (@code{info}).
The complete Emacs manual is available on-line in Info.
@item C-h k @var{key}
Display the name and documentation of the command that @var{key} runs
(@code{describe-key}).
@item C-h l
Display a description of the last 100 characters you typed
(@code{view-lossage}).
@item C-h m
Display documentation of the current major mode (@code{describe-mode}).
@item C-h p
Find packages by topic keyword (@code{finder-by-keyword}).
@item C-h s
Display the current contents of the syntax table, plus an explanation of
what they mean (@code{describe-syntax}).  @xref{Syntax}.
@item C-h t
Enter the Emacs interactive tutorial (@code{help-with-tutorial}).
@item C-h v @var{var} @key{RET}
Display the documentation of the Lisp variable @var{var}
(@code{describe-variable}).
@item C-h w @var{command} @key{RET}
Show which keys run the command named @var{command} (@code{where-is}).
@item C-h C @var{coding} @key{RET}
Describe coding system @var{coding}
(@code{describe-coding-system}).
@item C-h C @key{RET}
Describe the coding systems currently in use.
@item C-h I @var{method} @key{RET}
Describe an input method (@code{describe-input-method}).
@item C-h L @var{language-env} @key{RET}
Display information on the character sets, coding systems, and input
methods used for language environment @var{language-env}
(@code{describe-language-environment}).
@item C-h F @var{function} @key{RET}
Enter Info and go to the node documenting the Emacs function @var{function}
(@code{Info-goto-emacs-command-node}).
@item C-h K @var{key}
Enter Info and go to the node where the key sequence @var{key} is
documented (@code{Info-goto-emacs-key-command-node}).
@item C-h S @var{symbol} @key{RET}
Display the Info documentation on symbol @var{symbol} according to the
programming language you are editing (@code{info-lookup-symbol}).
@item C-h .
Display a help message associated with special text areas, such as
links in @samp{*Help*} buffers (@code{display-local-help}).
@end table

@node Key Help
@section Documentation for a Key

@kindex C-h c
@findex describe-key-briefly
  The most basic @kbd{C-h} commands are @kbd{C-h c}
(@code{describe-key-briefly}) and @w{@kbd{C-h k}} (@code{describe-key}).
@kbd{C-h c @var{key}} displays in the echo area the name of the command
that @var{key} is bound to.  For example, @kbd{C-h c C-f} displays
@samp{forward-char}.  Since command names are chosen to describe what
the commands do, this is a good way to get a very brief description of
what @var{key} does.

@kindex C-h k
@findex describe-key
  @kbd{C-h k @var{key}} is similar but gives more information: it
displays the documentation string of the command as well as its name.
This is too big for the echo area, so a window is used for the display.

@kindex C-h K
@findex Info-goto-emacs-key-command-node
  To find the documentation of a key sequence, type @kbd{C-h K} and
then enter that key sequence.  This looks up the description of the
command invoked by the key in whichever manual describes it (this need
not be the Emacs manual).  @kbd{C-h K} runs the command
@code{Info-goto-emacs-key-command-node}.

  @kbd{C-h c}, @kbd{C-h k} and @kbd{C-h K} work for any sort of key
sequences, including function keys, menus, and mouse events.  For
instance, you can type @kbd{C-h k} and then select a menu item from
the menu bar, to show the documentation string of the command that
menu item runs.

@kindex C-h w
@findex where-is
  @kbd{C-h w @var{command} @key{RET}} tells you what keys are bound to
@var{command}.  It displays a list of the keys in the echo area.  If it
says the command is not on any key, you must use @kbd{M-x} to run it.
@kbd{C-h w} runs the command @code{where-is}.

@node Name Help
@section Help by Command or Variable Name

@kindex C-h f
@findex describe-function
  @kbd{C-h f} (@code{describe-function}) reads the name of a Lisp function
using the minibuffer, then displays that function's documentation string
in a window.  Since commands are Lisp functions, you can use this to get
the documentation of a command that you know by name.  For example,

@example
C-h f auto-fill-mode @key{RET}
@end example

@noindent
displays the documentation of @code{auto-fill-mode}.  This is the only
way to get the documentation of a command that is not bound to any key
(one which you would normally run using @kbd{M-x}).

  @kbd{C-h f} is also useful for Lisp functions that you are planning
to use in a Lisp program.  For example, if you have just written the
expression @code{(make-vector len)} and want to check that you are
using @code{make-vector} properly, type @kbd{C-h f make-vector
@key{RET}}.  Because @kbd{C-h f} allows all function names, not just
command names, you may find that some of your favorite completion
abbreviations that work in @kbd{M-x} don't work in @kbd{C-h f}.  An
abbreviation may be unique among command names, yet fail to be unique
when other function names are allowed.

  The default function name for @kbd{C-h f} to describe, if you type
just @key{RET}, is the name of the function called by the innermost Lisp
expression in the buffer around point, @emph{provided} that is a valid,
defined Lisp function name.  For example, if point is located following
the text @samp{(make-vector (car x)}, the innermost list containing
point is the one that starts with @samp{(make-vector}, so the default is
to describe the function @code{make-vector}.

  @kbd{C-h f} is often useful just to verify that you have the right
spelling for the function name.  If @kbd{C-h f} mentions a name from the
buffer as the default, that name must be defined as a Lisp function.  If
that is all you want to know, just type @kbd{C-g} to cancel the @kbd{C-h
f} command, then go on editing.

  @kbd{C-h v} (@code{describe-variable}) is like @kbd{C-h f} but describes
Lisp variables instead of Lisp functions.  Its default is the Lisp symbol
around or before point, but only if that is the name of a known Lisp
variable.  @xref{Variables}.

  Help buffers describing Emacs variables and functions normally have
hyperlinks to the definition, if you have the source files installed.
(@xref{Hyperlinking}.)  If you know Lisp (or C), this provides the
ultimate documentation.  If you don't know Lisp, you should learn it.
(The Introduction to Emacs Lisp Programming, available from the FSF
through fsf.org, is a good way to get started.)  Emacs won't be happy
if it feels you are just @emph{using} Emacs, treating it as an object
program.  If you really love Emacs, show that you care by reading the
source code.

@kindex C-h F
@findex Info-goto-emacs-command-node
  To find a specific function's documentation in a manual, use
@kbd{C-h F} (@code{Info-goto-emacs-command-node}).  This knows
about various manuals, not just the Emacs manual, and finds the
right one.

@node Apropos
@section Apropos

  A more sophisticated sort of question to ask is, ``What are the
commands for working with files?''  The @dfn{apropos} commands ask
such questions---they look for things whose names match an
@dfn{apropos pattern}, which means either a word, a list of words, or
a regular expression.  Each apropos command displays a list of
matching items in a special buffer.

@table @kbd
@item C-h a @var{pattern} @key{RET}
Search for commands whose names match @var{pattern}.

@item M-x apropos @key{RET} @var{pattern} @key{RET}
Similar, but it searches for noninteractive functions and for
variables, as well as commands.

@item M-x apropos-variable @key{RET} @var{pattern} @key{RET}
Similar, but it searches for variables only.

@item M-x apropos-value @key{RET} @var{pattern} @key{RET}
Similar, but it searches for variables based on their values, or
functions based on their definitions.

@item C-h d @var{pattern} @key{RET}
Search the @emph{documentation strings} (the built-in short
descriptions) of all variables and functions (not their names) for a
match for @var{pattern}.
@end table

@kindex C-h a
@findex apropos-command
@cindex apropos
  To find the commands that work on files, type @kbd{C-h a file
@key{RET}}.  This displays a list of all command names that contain
@samp{file}, including @code{copy-file}, @code{find-file}, and so on.
With each command name appears a brief description of how to use the
command, and what keys you can currently invoke it with.  For example,
it would say that you can invoke @code{find-file} by typing @kbd{C-x
C-f}.  The @kbd{a} in @kbd{C-h a} stands for ``Apropos''; @kbd{C-h a}
runs the command @code{apropos-command}.  This command normally checks
only commands (interactive functions); if you specify a prefix
argument, it checks noninteractive functions as well.

  If you want more information about a function definition, variable or
symbol property listed in the Apropos buffer, you can click on it with
@kbd{Mouse-1} or @kbd{Mouse-2}, or move there and type @key{RET}.

  @kbd{C-h a} with a single word can find too many matches.  Don't
just give up; you can give Apropos a list of words to search for.
When you specify more than one word in the apropos pattern, a name
must contain at least two of the words in order to match.  Thus, if
you are looking for commands to kill a chunk of text before point, you
could try @kbd{C-h a kill back backward behind before @key{RET}}.

  For even greater flexibility, you can specify a regular expression
(@pxref{Regexps}).  An apropos pattern is interpreted as a regular
expression if it contains any of the regular expression special
characters, @samp{^$*+?.\[}.

  Here is a set of arguments to give to @kbd{C-h a} that covers many
classes of Emacs commands, since there are strong conventions for
naming the standard Emacs commands.  By giving you a feel for the
naming conventions, this set should also serve to aid you in
developing a technique for picking Apropos keywords.

@quotation
char, line, word, sentence, paragraph, region, page, sexp, list, defun,
rect, buffer, frame, window, face, file, dir, register, mode, beginning, end,
forward, backward, next, previous, up, down, search, goto, kill, delete,
mark, insert, yank, fill, indent, case, change, set, what, list, find,
view, describe, default.
@end quotation

@findex apropos
  To list all Lisp symbols that contain a match for an Apropos pattern,
not just the ones that are defined as commands, use the command
@kbd{M-x apropos} instead of @kbd{C-h a}.  This command does not check
key bindings by default; specify a numeric argument if you want it to
check them.

@findex apropos-variable
  To list user-customizable variables that match an apropos pattern,
use the command @kbd{M-x apropos-variable}.  If you specify a prefix
argument, it checks all variables.

@kindex C-h d
@findex apropos-documentation
  The @code{apropos-documentation} command is like @code{apropos}
except that it searches documentation strings instead of symbol names
for matches for the specified Apropos pattern.

@findex apropos-value
  The @code{apropos-value} command is like @code{apropos} except that
it searches variables' values for matches for the pattern.  With a
prefix argument, it also checks symbols' function definitions and
property lists.

@vindex apropos-do-all
  If the variable @code{apropos-do-all} is non-@code{nil}, the commands
above all behave as if they had been given a prefix argument.

@vindex apropos-sort-by-scores
@cindex apropos search results, order by score
  By default, Apropos lists the search results in alphabetical order.
If the variable @code{apropos-sort-by-scores} is non-@code{nil},
Apropos tries to guess the relevance of each result, and displays the
most relevant ones first.

@vindex apropos-documentation-sort-by-scores
  By default, Apropos lists the search results for
@code{apropos-documentation} in order of relevance of the match.  If
the variable @code{apropos-documentation-sort-by-scores} is
@code{nil}, Apropos lists the symbols found in alphabetical order.

@node Library Keywords
@section Keyword Search for Lisp Libraries

@kindex C-h p
@findex finder-by-keyword
The @kbd{C-h p} command lets you search the standard Emacs Lisp
libraries by topic keywords.  Here is a partial list of keywords you can
use:

@multitable {emulations} {aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa}
@item abbrev@tab abbreviation handling, typing shortcuts, macros.
@item bib@tab code related to the @code{bib} bibliography processor.
@item c@tab support for the C language and related languages.
@item calendar@tab calendar and time management support.
@item comm@tab communications, networking, remote access to files.
@item convenience@tab convenience features for faster editing.
@item data@tab support for editing files of data.
@item docs@tab support for Emacs documentation.
@item emulations@tab emulations of other editors.
@item extensions@tab Emacs Lisp language extensions.
@item faces@tab support for multiple fonts.
@item files@tab support for editing and manipulating files.
@item frames@tab support for Emacs frames and window systems.
@item games@tab games, jokes and amusements.
@item hardware@tab support for interfacing with exotic hardware.
@item help@tab support for on-line help systems.
@item hypermedia@tab support for links between text or other media types.
@item i18n@tab internationalization and alternate character-set support.
@item internal@tab code for Emacs internals, build process, defaults.
@item languages@tab specialized modes for editing programming languages.
@item lisp@tab Lisp support, including Emacs Lisp.
@item local@tab code local to your site.
@item maint@tab maintenance aids for the Emacs development group.
@item mail@tab modes for electronic-mail handling.
@item matching@tab various sorts of searching and matching.
@item mouse@tab mouse support.
@item multimedia@tab images and sound support.
@item news@tab support for netnews reading and posting.
@item oop@tab support for object-oriented programming.
@item outlines@tab support for hierarchical outlining.
@item processes@tab process, subshell, compilation, and job control support.
@item terminals@tab support for terminal types.
@item tex@tab supporting code for the @TeX{} formatter.
@item tools@tab programming tools.
@item unix@tab front-ends/assistants for, or emulators of, UNIX-like features.
@item wp@tab word processing.
@end multitable

@node Language Help
@section Help for International Language Support

  You can use the command @kbd{C-h L}
(@code{describe-language-environment}) to find out information about
the support for a specific language environment.  @xref{Language
Environments}.  This tells you which languages this language
environment is useful for, and lists the character sets, coding
systems, and input methods that it operates on.  It also shows some
sample text to illustrate scripts.

  The command @kbd{C-h h} (@code{view-hello-file}) displays the file
@file{etc/HELLO}, which shows how to say ``hello'' in many languages.

  The command @kbd{C-h I} (@code{describe-input-method}) describes
information about input methods---either a specified input method, or by
default the input method in use.  @xref{Input Methods}.

  The command @kbd{C-h C} (@code{describe-coding-system}) describes
information about coding systems---either a specified coding system, or
the ones currently in use.  @xref{Coding Systems}.

@node Help Mode
@section Help Mode Commands

  Help buffers provide the same commands as View mode (@pxref{Misc File
Ops}), plus a few special commands of their own.

@table @kbd
@item @key{SPC}
Scroll forward.
@item @key{DEL}
Scroll backward.
@item @key{RET}
Follow a cross reference at point.
@item @key{TAB}
Move point forward to the next cross reference.
@item S-@key{TAB}
Move point back to the previous cross reference.
@item Mouse-1
@itemx Mouse-2
Follow a cross reference that you click on.
@end table

  When a function name (@pxref{M-x,, Running Commands by Name}) or
variable name (@pxref{Variables}) appears in the documentation, it
normally appears inside paired single-quotes.  You can click on the
name with @kbd{Mouse-1} or @kbd{Mouse-2}, or move point there and type
@key{RET}, to view the documentation of that command or variable.  Use
@kbd{C-c C-b} to retrace your steps.

@cindex URL, viewing in help
@cindex help, viewing web pages
@cindex viewing web pages in help
@cindex web pages, viewing in help
@findex browse-url
  You can follow cross references to URLs (web pages) as well.  When
you follow a cross reference that is a URL, the @code{browse-url}
command is used to view the web page in a browser of your choosing.
@xref{Browse-URL}.

@kindex @key{TAB} @r{(Help mode)}
@findex help-next-ref
@kindex S-@key{TAB} @r{(Help mode)}
@findex help-previous-ref
  There are convenient commands for moving point to cross references in
the help text.  @key{TAB} (@code{help-next-ref}) moves point down to the
next cross reference.  Use @kbd{S-@key{TAB}} to move point up to the
previous cross reference (@code{help-previous-ref}).

@node Misc Help
@section Other Help Commands

@kindex C-h i
@findex info
@cindex Info
@cindex manuals, on-line
@cindex on-line manuals
  @kbd{C-h i} (@code{info}) runs the Info program, which is used for
browsing through structured documentation files.  The entire Emacs manual
is available within Info.  Eventually all the documentation of the GNU
system will be available.  Type @kbd{h} after entering Info to run
a tutorial on using Info.

@cindex find Info manual by its file name
  With a numeric argument, @kbd{C-h i} selects an Info buffer with the
number appended to the default @samp{*info*} buffer name
(e.g. @samp{*info*<2>}).  This is useful if you want to browse
multiple Info manuals simultaneously.  If you specify just @kbd{C-u}
as the prefix argument, @kbd{C-h i} prompts for the name of a
documentation file.  This way, you can browse a file which doesn't
have an entry in the top-level Info menu.  It is also handy when you
need to get to the documentation quickly, and you know the exact name
of the file.

  The help commands @kbd{C-h F @var{function} @key{RET}} and @kbd{C-h
K @var{key}}, described above, enter Info and go straight to the
documentation of @var{function} or @var{key}.

@kindex C-h S
@findex info-lookup-symbol
  When editing a program, if you have an Info version of the manual
for the programming language, you can use the command @kbd{C-h S}
(@code{info-lookup-symbol}) to refer to the manual documentation for a
symbol (keyword, function or variable).  The details of how this
command works depend on the major mode.

@kindex C-h l
@findex view-lossage
  If something surprising happens, and you are not sure what commands you
typed, use @kbd{C-h l} (@code{view-lossage}).  @kbd{C-h l} displays the last
100 command characters you typed in.  If you see commands that you don't
know, you can use @kbd{C-h c} to find out what they do.

@kindex C-h e
@findex view-echo-area-messages
  To review messages that recently appeared in the echo area, use
@kbd{C-h e} (@code{view-echo-area-messages}).  This displays the
buffer @code{*Messages*}, where those messages are kept.

@kindex C-h m
@findex describe-mode
  Emacs has numerous major modes, each of which redefines a few keys and
makes a few other changes in how editing works.  @kbd{C-h m}
(@code{describe-mode}) displays documentation on the current major mode,
which normally describes all the commands that are changed in this
mode.

@kindex C-h b
@findex describe-bindings
  @kbd{C-h b} (@code{describe-bindings}) and @kbd{C-h s}
(@code{describe-syntax}) present other information about the current
Emacs mode.  @kbd{C-h b} displays a list of all the key bindings now in
effect, showing the local bindings defined by the current minor modes first,
then the local bindings defined by the current major mode, and finally
the global bindings (@pxref{Key Bindings}).  @kbd{C-h s} displays the
contents of the syntax table, with explanations of each character's
syntax (@pxref{Syntax}).

  You can get a similar list for a particular prefix key by typing
@kbd{C-h} after the prefix key.  (There are a few prefix keys for which
this does not work---those that provide their own bindings for
@kbd{C-h}.  One of these is @key{ESC}, because @kbd{@key{ESC} C-h} is
actually @kbd{C-M-h}, which marks a defun.)

@node Help Files
@section Help Files

  The Emacs help commands described above display the state of data
bases within Emacs.  Emacs has a few other help commands that display
pre-written help files.  These commands all have the form @kbd{C-h
C-@var{char}}; that is, @kbd{C-h} followed by a control character.

@kindex C-h C-c
@findex describe-copying
@kindex C-h C-d
@findex describe-distribution
@kindex C-h C-e
@findex view-emacs-problems
@kindex C-h C-f
@findex view-emacs-FAQ
@kindex C-h C-n
@findex view-emacs-news
@kindex C-h C-p
@findex describe-project
@kindex C-h C-t
@findex view-emacs-todo
@kindex C-h C-w
@findex describe-no-warranty
  The other @kbd{C-h} options display various files containing useful
information.

@table @kbd
@item C-h C-c
Displays the Emacs copying conditions (@code{describe-copying}).
These are the rules under which you can copy and redistribute Emacs.
@item C-h C-d
Displays information on how to download or order the latest version of
Emacs and other GNU software (@code{describe-distribution}).
@item C-h C-e
Displays the list of known Emacs problems, sometimes with suggested
workarounds (@code{view-emacs-problems}).
@item C-h C-f
Displays the Emacs frequently-answered-questions list (@code{view-emacs-FAQ}).
@item C-h C-n
Displays the Emacs ``news'' file, which lists new Emacs features, most
recent first (@code{view-emacs-news}).
@item C-h C-p
Displays general information about the GNU Project
(@code{describe-project}).
@item C-h C-t
Displays the Emacs to-do list (@code{view-todo}).
@item C-h C-w
Displays the full details on the complete absence of warranty for GNU
Emacs (@code{describe-no-warranty}).
@end table

@node Help Echo
@section Help on Active Text and Tooltips

@cindex tooltips
@cindex balloon help
  When a region of text is ``active,'' so that you can select it with
the mouse or a key like @kbd{RET}, it often has associated help text.
Areas of the mode line are examples.  On most window systems, the help
text is displayed as a ``tooltip'' (sometimes known as ``balloon
help''), when you move the mouse over the active text.  @xref{Tooltips}.
On some systems, it is shown in the echo area.  On text-only
terminals, Emacs may not be able to follow the mouse and hence will
not show the help text on mouse-over.

@kindex C-h .
@findex display-local-help
@vindex help-at-pt-display-when-idle
  You can also access text region help info using the keyboard.  The
command @kbd{C-h .} (@code{display-local-help}) displays any help text
associated with the text at point, using the echo area.  If you want
help text to be displayed automatically whenever it is available at
point, set the variable @code{help-at-pt-display-when-idle} to
@code{t}.

@ignore
   arch-tag: 6f33ab62-bc75-4367-8057-fd67cc15c3a1
@end ignore