1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
3 @c See file emacs.texi for copying conditions.
4 @node Glossary, Key Index, Intro, Top
9 An abbrev is a text string which expands into a different text string
10 when present in the buffer. For example, you might define a few letters
11 as an abbrev for a long phrase that you want to insert frequently.
15 Aborting means getting out of a recursive edit (q.v.@:). The
16 commands @kbd{C-]} and @kbd{M-x top-level} are used for this.
20 Alt is the name of a modifier bit which a keyboard input character may
21 have. To make a character Alt, type it while holding down the @key{ALT}
22 key. Such characters are given names that start with @kbd{Alt-}
23 (usually written @kbd{A-} for short). (Note that many terminals have a
24 key labeled @key{ALT} which is really a @key{META} key.) @xref{User
28 See `numeric argument.'
31 An ASCII character is either an ASCII control character or an ASCII
32 printing character. @xref{User Input}.
34 @item ASCII control character
35 An ASCII control character is the Control version of an upper-case
36 letter, or the Control version of one of the characters @samp{@@[\]^_?}.
38 @item ASCII printing character
39 ASCII printing characters include letters, digits, space, and these
40 punctuation characters: @samp{!@@#$%^& *()_-+=|\~` @{@}[]:;"' <>,.?/}.
43 Auto Fill mode is a minor mode in which text that you insert is
44 automatically broken into lines of fixed width. @xref{Filling}.
47 Auto saving is the practice of saving the contents of an Emacs buffer in
48 a specially-named file, so that the information will not be lost if the
49 buffer is lost due to a system error or user error. @xref{Auto Save}.
52 Emacs automatically loads Lisp libraries when a Lisp program requests a
53 function or a variable from those libraries. This is called
54 `autoloading'. @xref{Lisp Libraries}.
57 A backtrace is a trace of a series of function calls showing how a
58 program arrived to a certain point. It is used mainly for finding and
59 correcting bugs (q.v.@:). Emacs can display a backtrace when it signals
60 an error or when you type @kbd{C-g} (see `quitting'). @xref{Checklist}.
63 A backup file records the contents that a file had before the current
64 editing session. Emacs makes backup files automatically to help you
65 track down or cancel changes you later regret making. @xref{Backup}.
67 @item Balance Parentheses
68 Emacs can balance parentheses manually or automatically. Manual
69 balancing is done by the commands to move over balanced expressions
70 (@pxref{Lists}). Automatic balancing is done by blinking or
71 highlighting the parenthesis that matches one just inserted
72 (@pxref{Matching,,Matching Parens}).
78 A base buffer is a buffer whose text is shared by an indirect buffer
82 To bind a key sequence means to give it a binding (q.v.@:).
86 A key sequence gets its meaning in Emacs by having a binding, which is a
87 command (q.v.@:), a Lisp function that is run when the user types that
88 sequence. @xref{Commands,Binding}. Customization often involves
89 rebinding a character to a different command function. The bindings of
90 all key sequences are recorded in the keymaps (q.v.@:). @xref{Keymaps}.
93 Blank lines are lines that contain only whitespace. Emacs has several
94 commands for operating on the blank lines in the buffer.
97 Bookmarks are akin to registers (q.v.@:) in that they record positions
98 in buffers to which you can return later. Unlike registers, bookmarks
99 persist between Emacs sessions.
102 The buffer is the basic editing unit; one buffer corresponds to one text
103 being edited. You can have several buffers, but at any time you are
104 editing only one, the `current buffer,' though several can be visible
105 when you are using multiple windows (q.v.@:). Most buffers are visiting
106 (q.v.@:) some file. @xref{Buffers}.
108 @item Buffer Selection History
109 Emacs keeps a buffer selection history which records how recently each
110 Emacs buffer has been selected. This is used for choosing a buffer to
111 select. @xref{Buffers}.
114 A bug is an incorrect or unreasonable behavior of a program, or
115 inaccurate or confusing documentation. Emacs developers treat bug
116 reports, both in Emacs code and its documentation, very seriously and
117 ask you to report any bugs you find. @xref{Bugs}.
119 @item Button Down Event
120 A button down event is the kind of input event generated right away when
121 you press a mouse button. @xref{Mouse Buttons}.
127 @kbd{C-} in the name of a character is an abbreviation for Control.
128 @xref{User Input,C-}.
131 @kbd{C-M-} in the name of a character is an abbreviation for
132 Control-Meta. @xref{User Input,C-M-}.
134 @item Case Conversion
135 Case conversion means changing text from upper case to lower case or
136 vice versa. @xref{Case}, for the commands for case conversion.
139 Characters form the contents of an Emacs buffer; see @ref{Text
140 Characters}. Also, key sequences (q.v.@:) are usually made up of
141 characters (though they may include other input events as well).
145 Emacs supports a number of character sets, each of which represents a
146 particular alphabet or script. @xref{International}.
148 @item Character Terminal
149 See `text-only terminal.'
152 A click event is the kind of input event generated when you press a
153 mouse button and release it without moving the mouse. @xref{Mouse Buttons}.
156 A clipboard is a buffer provided by the window system for transferring
157 text between applications. On the X Window system, the clipboard is
158 provided in addition to the primary selection (q.v.@:); on MS-Windows,
159 the clipboard is used @emph{instead} of the primary selection.
163 A coding system is an encoding for representing text characters in a
164 file or in a stream of information. Emacs has the ability to convert
165 text to or from a variety of coding systems when reading or writing it.
166 @xref{Coding Systems}.
169 A command is a Lisp function specially defined to be able to serve as a
170 key binding in Emacs. When you type a key sequence (q.v.@:), its
171 binding (q.v.@:) is looked up in the relevant keymaps (q.v.@:) to find
172 the command to run. @xref{Commands}.
174 @item Command History
175 See `minibuffer history.'
178 A command name is the name of a Lisp symbol which is a command
179 (@pxref{Commands}). You can invoke any command by its name using
180 @kbd{M-x} (@pxref{M-x}).
183 A comment is text in a program which is intended only for humans reading
184 the program, and which is marked specially so that it will be ignored
185 when the program is loaded or compiled. Emacs offers special commands
186 for creating, aligning and killing comments. @xref{Comments}.
189 Common Lisp is a dialect of Lisp (q.v.@:) much larger and more powerful
190 than Emacs Lisp. Emacs provides a subset of Common Lisp in the CL
191 package. @xref{, Common Lisp, , cl, Common Lisp Extensions}.
194 Compilation is the process of creating an executable program from source
195 code. Emacs has commands for compiling files of Emacs Lisp code
196 (@pxref{Byte Compilation,, Byte Compilation, elisp, the Emacs Lisp
197 Reference Manual}) and programs in C and other languages
198 (@pxref{Compilation}).
201 A complete key is a key sequence which fully specifies one action to be
202 performed by Emacs. For example, @kbd{X} and @kbd{C-f} and @kbd{C-x m}
203 are complete keys. Complete keys derive their meanings from being bound
204 (q.v.@:) to commands (q.v.@:). Thus, @kbd{X} is conventionally bound to
205 a command to insert @samp{X} in the buffer; @kbd{C-x m} is
206 conventionally bound to a command to begin composing a mail message.
210 Completion is what Emacs does when it automatically fills out an
211 abbreviation for a name into the entire name. Completion is done for
212 minibuffer (q.v.@:) arguments when the set of possible valid inputs
213 is known; for example, on command names, buffer names, and
214 file names. Completion occurs when @key{TAB}, @key{SPC} or @key{RET}
215 is typed. @xref{Completion}.@refill
217 @item Continuation Line
218 When a line of text is longer than the width of the window, it
219 takes up more than one screen line when displayed. We say that the
220 text line is continued, and all screen lines used for it after the
221 first are called continuation lines. @xref{Basic,Continuation,Basic
222 Editing}. A related Emacs feature is `filling' (q.v.@:).
224 @item Control Character
225 A control character is a character that you type by holding down the
226 @key{CTRL} key. Some control characters also have their own keys, so
227 that you can type them without using @key{CTRL}. For example,
228 @key{RET}, @key{TAB}, @key{ESC} and @key{DEL} are all control
229 characters. @xref{User Input}.
232 A copyleft is a notice giving the public legal permission to
233 redistribute a program or other work of art. Copylefts are used by
234 left-wing programmers to promote freedom and cooperation, just as
235 copyrights are used by right-wing programmers to gain power over other
238 The particular form of copyleft used by the GNU project is called the
239 GNU General Public License. @xref{Copying}.
242 The current buffer in Emacs is the Emacs buffer on which most editing
243 commands operate. You can select any Emacs buffer as the current one.
247 The current line is a line point is on (@pxref{Point}).
249 @item Current Paragraph
250 The current paragraph is the paragraph that point is in. If point is
251 between paragraphs, the current paragraph is the one that follows point.
255 The current defun is a defun (q.v.@:) that point is in. If point is
256 between defuns, the current defun is the one that follows point.
260 The cursor is the rectangle on the screen which indicates the position
261 called point (q.v.@:) at which insertion and deletion takes place.
262 The cursor is on or under the character that follows point. Often
263 people speak of `the cursor' when, strictly speaking, they mean
264 `point.' @xref{Basic,Cursor,Basic Editing}.
267 Customization is making minor changes in the way Emacs works. It is
268 often done by setting variables (@pxref{Variables}) or by rebinding
269 key sequences (@pxref{Keymaps}).
272 See `killing' and `yanking.'
274 @item Default Argument
275 The default for an argument is the value that will be assumed if you
276 do not specify one. When the minibuffer is used to read an argument,
277 the default argument is used if you just type @key{RET}.
281 A default is the value that is used for a certain purpose if and when
282 you do not specify a value to use.
284 @item Default Directory
285 When you specify a file name that does not start with @samp{/} or @samp{~},
286 it is interpreted relative to the current buffer's default directory.
287 (On MS-Windows and MS-DOS, file names which start with a drive letter
288 @samp{@var{x}:} are treated as absolute, not relative.)
289 @xref{Minibuffer File,Default Directory}.
292 A defun is a list at the top level of parenthesis or bracket structure
293 in a program. It is so named because most such lists in Lisp programs
294 are calls to the Lisp function @code{defun}. @xref{Defuns}.
297 @key{DEL} is a character that runs the command to delete one character of
298 text. @xref{Basic,DEL,Basic Editing}.
301 Deletion means erasing text without copying it into the kill ring
302 (q.v.@:). The alternative is killing (q.v.@:). @xref{Killing,Deletion}.
304 @item Deletion of Files
305 Deleting a file means erasing it from the file system.
306 @xref{Misc File Ops}.
308 @item Deletion of Messages
309 Deleting a message means flagging it to be eliminated from your mail
310 file. Until you expunge (q.v.@:) the Rmail file, you can still undelete
311 the messages you have deleted. @xref{Rmail Deletion}.
313 @item Deletion of Windows
314 Deleting a window means eliminating it from the screen. Other windows
315 expand to use up the space. The deleted window can never come back,
316 but no actual text is thereby lost. @xref{Windows}.
319 File directories are named collections in the file system, within which
320 you can place individual files or subdirectories. @xref{Directories}.
323 Dired is the Emacs facility that displays the contents of a file
324 directory and allows you to ``edit the directory,'' performing
325 operations on the files in the directory. @xref{Dired}.
327 @item Disabled Command
328 A disabled command is one that you may not run without special
329 confirmation. The usual reason for disabling a command is that it is
330 confusing for beginning users. @xref{Disabling}.
333 Short for `button down event' (q.v.@:).
336 A drag event is the kind of input event generated when you press a mouse
337 button, move the mouse, and then release the button. @xref{Mouse
341 A dribble file is a file into which Emacs writes all the characters that
342 the user types on the keyboard. Dribble files are used to make a record
343 for debugging Emacs bugs. Emacs does not make a dribble file unless you
344 tell it to. @xref{Bugs}.
347 The echo area is the bottom line of the screen, used for echoing the
348 arguments to commands, for asking questions, and printing brief messages
349 (including error messages). The messages are stored in the buffer
350 @samp{*Messages*} so you can review them later. @xref{Echo Area}.
353 Echoing is acknowledging the receipt of commands by displaying them (in
354 the echo area). Emacs never echoes single-character key sequences;
355 longer key sequences echo only if you pause while typing them.
358 We say that a character is electric if it is normally self-inserting
359 (q.v.@:), but the current major mode (q.v.@:) redefines it to do something
360 else as well. For example, some programming language major modes define
361 particular delimiter characters to reindent the line or insert one or
362 more newlines in addition to self-insertion.
365 End of line is a character or characters which signal an end of a text
366 line. On GNU and Unix systems, this is a newline (.q.v.@:), but other
367 systems have other conventions. @xref{Coding Systems,end-of-line}.
368 Emacs can recognize several end-of-line conventions in files and convert
371 @item Environment Variable
372 An environment variable is one of a collection of variables stored by
373 the operating system, each one having a name and a value. Emacs can
374 access environment variables set by its parent shell, and it can set
375 variables in the environment it passes to programs it invokes.
382 An error occurs when an Emacs command cannot execute in the current
383 circumstances. When an error occurs, execution of the command stops
384 (unless the command has been programmed to do otherwise) and Emacs
385 reports the error by printing an error message (q.v.@:). Type-ahead
386 is discarded. Then Emacs is ready to read another editing command.
389 An error message is a single line of output displayed by Emacs when the
390 user asks for something impossible to do (such as, killing text
391 forward when point is at the end of the buffer). They appear in the
392 echo area, accompanied by a beep.
395 @key{ESC} is a character used as a prefix for typing Meta characters on
396 keyboards lacking a @key{META} key. Unlike the @key{META} key (which,
397 like the @key{SHIFT} key, is held down while another character is
398 typed), you press the @key{ESC} key as you would press a letter key, and
399 it applies to the next character you type.
402 Expunging an Rmail file or Dired buffer or a Gnus newsgroup buffer is an
403 operation that truly discards the messages or files you have previously
404 flagged for deletion.
407 A face is a style of displaying characters. It specifies attributes
408 such as font family and size, foreground and background colors,
409 underline and strike-through, background stipple, etc. Emacs provides
410 features to associate specific faces with portions of buffer text, in
411 order to display that text as specified by the face attributes.
414 Emacs used file locking to notice when two different users
415 start to edit one file at the same time. @xref{Interlocking}.
418 A file name is a name that refers to a file. File names may be relative
419 or absolute; the meaning of a relative file name depends on the current
420 directory, but an absolute file name refers to the same file regardless
421 of which directory is current. On GNU and Unix systems, an absolute
422 file name starts with a slash (the root directory) or with @samp{~/} or
423 @samp{~@var{user}/} (a home directory). On MS-Windows/MS-DOS, and
424 absolute file name can also start with a drive letter and a colon
427 Some people use the term ``pathname'' for file names, but we do not;
428 we use the word ``path'' only in the term ``search path'' (q.v.@:).
430 @item File-Name Component
431 A file-name component names a file directly within a particular
432 directory. On GNU and Unix systems, a file name is a sequence of
433 file-name components, separated by slashes. For example, @file{foo/bar}
434 is a file name containing two components, @samp{foo} and @samp{bar}; it
435 refers to the file named @samp{bar} in the directory named @samp{foo} in
436 the current directory. MS-DOS/MS-Windows file names can also use
437 backslashes to separate components, as in @file{foo\bar}.
440 The fill prefix is a string that should be expected at the beginning
441 of each line when filling is done. It is not regarded as part of the
442 text to be filled. @xref{Filling}.
445 Filling text means shifting text between consecutive lines so that all
446 the lines are approximately the same length. @xref{Filling}. Some
447 other editors call this feature `line wrapping.'
450 Font Lock is a mode that highlights parts of buffer text according to
451 its syntax. @xref{Font Lock}.
454 A fontset is a named collection of fonts. A fontset specification lists
455 character sets and which font to use to display each of them. Fontsets
456 make it easy to change several fonts at once by specifying the name of a
457 fontset, rather than changing each font separately. @xref{Fontsets}.
460 Formatted text is text that displays with formatting information while
461 you edit. Formatting information includes fonts, colors, and specified
462 margins. @xref{Formatted Text}.
464 @item Formfeed Character
468 A frame is a rectangular cluster of Emacs windows. Emacs starts out
469 with one frame, but you can create more. You can subdivide each frame
470 into Emacs windows (q.v.@:). When you are using a windowing system, all
471 the frames can be visible at the same time. @xref{Frames}. Some
472 other editors use the term ``window'' for this, but in Emacs a window
473 means something else.
476 On windowed displays, there's a narrow portion of the frame (q.v.@:)
477 between the text area and the window's border. Emacs displays the
478 fringe using a special face (q.v.@:) called @code{fringe}.
482 FTP is an acronym for File Transfer Protocol. Emacs uses an FTP client
483 program to provide access to remote files (q.v.@:).
486 A function key is a key on the keyboard that sends input but does not
487 correspond to any character. @xref{Function Keys}.
490 Global means ``independent of the current environment; in effect
491 throughout Emacs.'' It is the opposite of local (q.v.@:). Particular
492 examples of the use of `global' appear below.
495 A global definition of an abbrev (q.v.@:) is effective in all major
496 modes that do not have local (q.v.@:) definitions for the same abbrev.
500 The global keymap (q.v.@:) contains key bindings that are in effect
501 except when overridden by local key bindings in a major mode's local
502 keymap (q.v.@:). @xref{Keymaps}.
504 @item Global Mark Ring
505 The global mark ring records the series of buffers you have recently
506 set a mark (q.v.@:) in. In many cases you can use this to backtrack
507 through buffers you have been editing in, or in which you have found
508 tags (see `tags table'). @xref{Global Mark Ring}.
510 @item Global Substitution
511 Global substitution means replacing each occurrence of one string by
512 another string through a large amount of text. @xref{Replace}.
514 @item Global Variable
515 The global value of a variable (q.v.@:) takes effect in all buffers
516 that do not have their own local (q.v.@:) values for the variable.
519 @item Graphic Character
520 Graphic characters are those assigned pictorial images rather than
521 just names. All the non-Meta (q.v.@:) characters except for the
522 Control (q.v.@:) characters are graphic characters. These include
523 letters, digits, punctuation, and spaces; they do not include
524 @key{RET} or @key{ESC}. In Emacs, typing a graphic character inserts
525 that character (in ordinary editing modes). @xref{Basic,,Basic Editing}.
528 Highlighting text means displaying it with a different foreground and/or
529 background color to make it stand out from the rest of the text in the
533 Hardcopy means printed output. Emacs has commands for making printed
534 listings of text in Emacs buffers. @xref{Hardcopy}.
537 @key{HELP} is the Emacs name for @kbd{C-h} or @key{F1}. You can type
538 @key{HELP} at any time to ask what options you have, or to ask what any
539 command does. @xref{Help}.
542 Help echo is a short message printed in the echo area when the mouse
543 pointer is located on portions of display that require some
544 explanations. Emacs displays help echo for menu items, parts of the
545 mode line, tool-bar buttons, etc. On graphics displays, the messages
546 can be displayed as tooltips (q.v.@:). @xref{Tooltips}.
549 A hook is a list of functions to be called on specific occasions, such
550 as saving a buffer in a file, major mode activation, etc. By
551 customizing the various hooks, you can modify Emacs's behavior without
552 changing any of its code. @xref{Hooks}.
555 Hyper is the name of a modifier bit which a keyboard input character may
556 have. To make a character Hyper, type it while holding down the
557 @key{HYPER} key. Such characters are given names that start with
558 @kbd{Hyper-} (usually written @kbd{H-} for short). @xref{User Input,
562 An inbox is a file in which mail is delivered by the operating system.
563 Rmail transfers mail from inboxes to Rmail files (q.v.@:) in which the
564 mail is then stored permanently or until explicitly deleted.
567 @item Incremental Search
568 Emacs provides an incremental search facility, whereby Emacs searches
569 for the string as you type it. @xref{Incremental Search}.
572 Indentation means blank space at the beginning of a line. Most
573 programming languages have conventions for using indentation to
574 illuminate the structure of the program, and Emacs has special
575 commands to adjust indentation.
578 @item Indirect Buffer
579 An indirect buffer is a buffer that shares the text of another buffer,
580 called its base buffer (q.v.@:). @xref{Indirect Buffers}.
583 Info is the hypertext format used by the GNU project for writing
587 An input event represents, within Emacs, one action taken by the user on
588 the terminal. Input events include typing characters, typing function
589 keys, pressing or releasing mouse buttons, and switching between Emacs
590 frames. @xref{User Input}.
593 An input method is a system for entering non-ASCII text characters by
594 typing sequences of ASCII characters (q.v.@:). @xref{Input Methods}.
597 Insertion means copying text into the buffer, either from the keyboard
598 or from some other place in Emacs.
601 Interlocking is a feature for warning when you start to alter a file
602 that someone else is already editing. @xref{Interlocking,,Simultaneous
606 See `incremental search.'
609 Justification means adding extra spaces to lines of text to make them
610 come exactly to a specified width. @xref{Filling,Justification}.
613 Keyboard macros are a way of defining new Emacs commands from
614 sequences of existing ones, with no need to write a Lisp program.
615 @xref{Keyboard Macros}.
618 A key sequence (key, for short) is a sequence of input events (q.v.@:)
619 that are meaningful as a single unit. If the key sequence is enough to
620 specify one action, it is a complete key (q.v.@:); if it is not enough,
621 it is a prefix key (q.v.@:). @xref{Keys}.
624 The keymap is the data structure that records the bindings (q.v.@:) of
625 key sequences to the commands that they run. For example, the global
626 keymap binds the character @kbd{C-n} to the command function
627 @code{next-line}. @xref{Keymaps}.
629 @item Keyboard Translation Table
630 The keyboard translation table is an array that translates the character
631 codes that come from the terminal into the character codes that make up
632 key sequences. @xref{Keyboard Translations}.
635 The kill ring is where all text you have killed recently is saved.
636 You can reinsert any of the killed text still in the ring; this is
637 called yanking (q.v.@:). @xref{Yanking}.
640 Killing means erasing text and saving it on the kill ring so it can be
641 yanked (q.v.@:) later. Some other systems call this ``cutting.''
642 Most Emacs commands to erase text do killing, as opposed to deletion
643 (q.v.@:). @xref{Killing}.
646 Killing a job (such as, an invocation of Emacs) means making it cease
647 to exist. Any data within it, if not saved in a file, is lost.
650 @item Language Environment
651 Your choice of language environment specifies defaults for the input
652 method (q.v.@:) and coding system (q.v.@:). @xref{Language
653 Environments}. These defaults are relevant if you edit non-ASCII text
654 (@pxref{International}).
660 Lisp is a programming language. Most of Emacs is written in a dialect
661 of Lisp, called Emacs Lisp, that is extended with special features which
662 make it especially suitable for text editing tasks.
665 A list is, approximately, a text string beginning with an open
666 parenthesis and ending with the matching close parenthesis. In C mode
667 and other non-Lisp modes, groupings surrounded by other kinds of matched
668 delimiters appropriate to the language, such as braces, are also
669 considered lists. Emacs has special commands for many operations on
673 Local means ``in effect only in a particular context''; the relevant
674 kind of context is a particular function execution, a particular
675 buffer, or a particular major mode. It is the opposite of `global'
676 (q.v.@:). Specific uses of `local' in Emacs terminology appear below.
679 A local abbrev definition is effective only if a particular major mode
680 is selected. In that major mode, it overrides any global definition
681 for the same abbrev. @xref{Abbrevs}.
684 A local keymap is used in a particular major mode; the key bindings
685 (q.v.@:) in the current local keymap override global bindings of the
686 same key sequences. @xref{Keymaps}.
689 A local value of a variable (q.v.@:) applies to only one buffer.
693 @kbd{M-} in the name of a character is an abbreviation for @key{META},
694 one of the modifier keys that can accompany any character.
698 @kbd{M-C-} in the name of a character is an abbreviation for
699 Control-Meta; it means the same thing as @kbd{C-M-}. If your
700 terminal lacks a real @key{META} key, you type a Control-Meta character by
701 typing @key{ESC} and then typing the corresponding Control character.
702 @xref{User Input,C-M-}.
705 @kbd{M-x} is the key sequence which is used to call an Emacs command by
706 name. This is how you run commands that are not bound to key sequences.
710 Mail means messages sent from one user to another through the computer
711 system, to be read at the recipient's convenience. Emacs has commands for
712 composing and sending mail, and for reading and editing the mail you have
713 received. @xref{Sending Mail}. @xref{Rmail}, for how to read mail.
715 @item Mail Composition Method
716 A mail composition method is a program runnable within Emacs for editing
717 and sending a mail message. Emacs lets you select from several
718 alternative mail composition methods. @xref{Mail Methods}.
721 The Emacs major modes are a mutually exclusive set of options, each of
722 which configures Emacs for editing a certain sort of text. Ideally,
723 each programming language has its own major mode. @xref{Major Modes}.
726 The mark points to a position in the text. It specifies one end of the
727 region (q.v.@:), point being the other end. Many commands operate on
728 all the text from point to the mark. Each buffer has its own mark.
732 The mark ring is used to hold several recent previous locations of the
733 mark, just in case you want to move back to them. Each buffer has its
734 own mark ring; in addition, there is a single global mark ring (q.v.@:).
738 The menu bar is the line at the top of an Emacs frame. It contains
739 words you can click on with the mouse to bring up menus, or you can use
740 a keyboard interface to navigate it. @xref{Menu Bars}.
746 Meta is the name of a modifier bit which a command character may have.
747 It is present in a character if the character is typed with the
748 @key{META} key held down. Such characters are given names that start
749 with @kbd{Meta-} (usually written @kbd{M-} for short). For example,
750 @kbd{M-<} is typed by holding down @key{META} and at the same time
751 typing @kbd{<} (which itself is done, on most terminals, by holding
752 down @key{SHIFT} and typing @kbd{,}). @xref{User Input,Meta}.
755 A Meta character is one whose character code includes the Meta bit.
758 The minibuffer is the window that appears when necessary inside the
759 echo area (q.v.@:), used for reading arguments to commands.
762 @item Minibuffer History
763 The minibuffer history records the text you have specified in the past
764 for minibuffer arguments, so you can conveniently use the same text
765 again. @xref{Minibuffer History}.
768 A minor mode is an optional feature of Emacs which can be switched on
769 or off independently of all other features. Each minor mode has a
770 command to turn it on or off. @xref{Minor Modes}.
772 @item Minor Mode Keymap
773 A minor mode keymap is a keymap that belongs to a minor mode and is
774 active when that mode is enabled. Minor mode keymaps take precedence
775 over the buffer's local keymap, just as the local keymap takes
776 precedence over the global keymap. @xref{Keymaps}.
779 The mode line is the line at the bottom of each window (q.v.@:), giving
780 status information on the buffer displayed in that window. @xref{Mode
783 @item Modified Buffer
784 A buffer (q.v.@:) is modified if its text has been changed since the
785 last time the buffer was saved (or since when it was created, if it
786 has never been saved). @xref{Saving}.
789 Moving text means erasing it from one place and inserting it in
790 another. The usual way to move text by killing (q.v.@:) and then
791 yanking (q.v.@:). @xref{Killing}.
794 MULE refers to the Emacs features for editing multilingual non-ASCII text
795 using multibyte characters (q.v.@:). @xref{International}.
797 @item Multibyte Character
798 A multibyte character is a character that takes up several bytes in a
799 buffer. Emacs uses multibyte characters to represent non-ASCII text,
800 since the number of non-ASCII characters is much more than 256.
801 @xref{International Intro}.
804 A named mark is a register (q.v.@:) in its role of recording a
805 location in text so that you can move point to that location.
809 Narrowing means creating a restriction (q.v.@:) that limits editing in
810 the current buffer to only a part of the text in the buffer. Text
811 outside that part is inaccessible to the user until the boundaries are
812 widened again, but it is still there, and saving the file saves it
813 all. @xref{Narrowing}.
816 Control-J characters in the buffer terminate lines of text and are
817 therefore also called newlines. @xref{Text Characters,Newline}.
822 @code{nil} is a value usually interpreted as a logical ``false.'' Its
823 opposite is @code{t}, interpreted as ``true.''
825 @item Numeric Argument
826 A numeric argument is a number, specified before a command, to change
827 the effect of the command. Often the numeric argument serves as a
828 repeat count. @xref{Arguments}.
831 Overwrite mode is a minor mode. When it is enabled, ordinary text
832 characters replace the existing text after point rather than pushing
833 it to the right. @xref{Minor Modes}.
836 A page is a unit of text, delimited by formfeed characters (ASCII
837 control-L, code 014) coming at the beginning of a line. Some Emacs
838 commands are provided for moving over and operating on pages.
842 Paragraphs are the medium-size unit of human-language text. There are
843 special Emacs commands for moving over and operating on paragraphs.
847 We say that certain Emacs commands parse words or expressions in the
848 text being edited. Really, all they know how to do is find the other
849 end of a word or expression. @xref{Syntax}.
852 Point is the place in the buffer at which insertion and deletion
853 occur. Point is considered to be between two characters, not at one
854 character. The terminal's cursor (q.v.@:) indicates the location of
855 point. @xref{Basic,Point}.
857 @item Prefix Argument
858 See `numeric argument.'
861 A prefix key is a key sequence (q.v.@:) whose sole function is to
862 introduce a set of longer key sequences. @kbd{C-x} is an example of
863 prefix key; any two-character sequence starting with @kbd{C-x} is
864 therefore a legitimate key sequence. @xref{Keys}.
866 @item Primary Rmail File
867 Your primary Rmail file is the file named @samp{RMAIL} in your home
868 directory. That's where Rmail stores your incoming mail, unless you
869 specify a different file name. @xref{Rmail}.
871 @item Primary Selection
872 The primary selection is one particular X selection (q.v.@:); it is the
873 selection that most X applications use for transferring text to and from
876 The Emacs kill commands set the primary selection and the yank command
877 uses the primary selection when appropriate. @xref{Killing}.
880 A prompt is text printed to ask the user for input. Displaying a prompt
881 is called prompting. Emacs prompts always appear in the echo area
882 (q.v.@:). One kind of prompting happens when the minibuffer is used to
883 read an argument (@pxref{Minibuffer}); the echoing which happens when
884 you pause in the middle of typing a multi-character key sequence is also
885 a kind of prompting (@pxref{Echo Area}).
888 Query-replace is an interactive string replacement feature provided by
889 Emacs. @xref{Query Replace}.
892 Quitting means canceling a partially typed command or a running
893 command, using @kbd{C-g} (or @kbd{C-@key{BREAK}} on MS-DOS). @xref{Quitting}.
896 Quoting means depriving a character of its usual special significance.
897 The most common kind of quoting in Emacs is with @kbd{C-q}. What
898 constitutes special significance depends on the context and on
899 convention. For example, an ``ordinary'' character as an Emacs command
900 inserts itself; so in this context, a special character is any character
901 that does not normally insert itself (such as @key{DEL}, for example),
902 and quoting it makes it insert itself as if it were not special. Not
903 all contexts allow quoting. @xref{Basic,Quoting,Basic Editing}.
905 @item Quoting File Names
906 Quoting a file name turns off the special significance of constructs
907 such as @samp{$}, @samp{~} and @samp{:}. @xref{Quoted File Names}.
909 @item Read-Only Buffer
910 A read-only buffer is one whose text you are not allowed to change.
911 Normally Emacs makes buffers read-only when they contain text which
912 has a special significance to Emacs; for example, Dired buffers.
913 Visiting a file that is write-protected also makes a read-only buffer.
917 A rectangle consists of the text in a given range of columns on a given
918 range of lines. Normally you specify a rectangle by putting point at
919 one corner and putting the mark at the opposite corner.
922 @item Recursive Editing Level
923 A recursive editing level is a state in which part of the execution of
924 a command involves asking the user to edit some text. This text may
925 or may not be the same as the text to which the command was applied.
926 The mode line indicates recursive editing levels with square brackets
927 (@samp{[} and @samp{]}). @xref{Recursive Edit}.
930 Redisplay is the process of correcting the image on the screen to
931 correspond to changes that have been made in the text being edited.
932 @xref{Screen,Redisplay}.
935 See `regular expression.'
938 The region is the text between point (q.v.@:) and the mark (q.v.@:).
939 Many commands operate on the text of the region. @xref{Mark,Region}.
942 Registers are named slots in which text or buffer positions or
943 rectangles can be saved for later use. @xref{Registers}. A related
944 Emacs feature is `bookmarks' (q.v.@:).
946 @item Regular Expression
947 A regular expression is a pattern that can match various text strings;
948 for example, @samp{a[0-9]+} matches @samp{a} followed by one or more
949 digits. @xref{Regexps}.
952 A remote file is a file that is stored on a system other than your own.
953 Emacs can access files on other computers provided that they are
954 connected to the same network as your machine. @xref{Remote Files}.
957 See `numeric argument.'
960 See `global substitution.'
963 A buffer's restriction is the amount of text, at the beginning or the
964 end of the buffer, that is temporarily inaccessible. Giving a buffer a
965 nonzero amount of restriction is called narrowing (q.v.@:); removing
966 a restriction is called widening (q.v.@:). @xref{Narrowing}.
969 @key{RET} is a character that in Emacs runs the command to insert a
970 newline into the text. It is also used to terminate most arguments
971 read in the minibuffer (q.v.@:). @xref{User Input,Return}.
974 Reverting means returning to the original state. Emacs lets you
975 revert a buffer by re-reading its file from disk. @xref{Reverting}.
978 An Rmail file is a file containing text in a special format used by
979 Rmail for storing mail. @xref{Rmail}.
982 Saving a buffer means copying its text into the file that was visited
983 (q.v.@:) in that buffer. This is the way text in files actually gets
984 changed by your Emacs editing. @xref{Saving}.
987 A scroll bar is a tall thin hollow box that appears at the side of a
988 window. You can use mouse commands in the scroll bar to scroll the
989 window. The scroll bar feature is supported only under windowing
990 systems. @xref{Scroll Bars}.
993 Scrolling means shifting the text in the Emacs window so as to see a
994 different part of the buffer. @xref{Display,Scrolling}.
997 Searching means moving point to the next occurrence of a specified
998 string or the next match for a specified regular expression.
1002 A search path is a list of directory names, to be used for searching for
1003 files for certain purposes. For example, the variable @code{load-path}
1004 holds a search path for finding Lisp library files. @xref{Lisp Libraries}.
1006 @item Secondary Selection
1007 The secondary selection is one particular X selection; some X
1008 applications can use it for transferring text to and from other
1009 applications. Emacs has special mouse commands for transferring text
1010 using the secondary selection. @xref{Secondary Selection}.
1013 Selecting a buffer means making it the current (q.v.@:) buffer.
1014 @xref{Buffers,Selecting}.
1017 Windowing systems allow an application program to specify
1018 selections whose values are text. A program can also read the
1019 selections that other programs have set up. This is the principal way
1020 of transferring text between window applications. Emacs has commands to
1021 work with the primary (q.v.@:) selection and the secondary (q.v.@:)
1022 selection, and also with the clipboard (q.v.@:).
1024 @item Self-Documentation
1025 Self-documentation is the feature of Emacs which can tell you what any
1026 command does, or give you a list of all commands related to a topic
1027 you specify. You ask for self-documentation with the help character,
1028 @kbd{C-h}. @xref{Help}.
1030 @item Self-Inserting Character
1031 A character is self-inserting if typing that character inserts that
1032 character in the buffer. Ordinary printing and whitespace characters
1033 are self-inserting in Emacs, except in certain special major modes.
1036 Emacs has commands for moving by or killing by sentences.
1040 A sexp (short for ``s-expression'') is the basic syntactic unit of Lisp
1041 in its textual form: either a list, or Lisp atom. Many Emacs commands
1042 operate on sexps. The term `sexp' is generalized to languages other
1043 than Lisp, to mean a syntactically recognizable expression, such as a
1044 block or a parenthesized expression in C. @xref{Lists,Sexps}.
1046 @item Simultaneous Editing
1047 Simultaneous editing means two users modifying the same file at once.
1048 Simultaneous editing if not detected can cause one user to lose his
1049 work. Emacs detects all cases of simultaneous editing and warns one of
1050 the users to investigate. @xref{Interlocking,,Simultaneous Editing}.
1053 Speedbar is a special tall frame that provides fast access to Emacs
1054 buffers, functions within those buffers, Info nodes, and other
1055 interesting parts of text within Emacs. @xref{Speedbar}.
1057 @item Spell Checking
1058 Spell checking means checking correctness of the written form of each
1059 one of the words in a text. Emacs uses the Ispell spelling-checker
1060 program to check the spelling of parts of a buffer via a convenient user
1061 interface. @xref{Spelling}.
1064 A string is a kind of Lisp data object which contains a sequence of
1065 characters. Many Emacs variables are intended to have strings as
1066 values. The Lisp syntax for a string consists of the characters in the
1067 string with a @samp{"} before and another @samp{"} after. A @samp{"}
1068 that is part of the string must be written as @samp{\"} and a @samp{\}
1069 that is part of the string must be written as @samp{\\}. All other
1070 characters, including newline, can be included just by writing them
1071 inside the string; however, backslash sequences as in C, such as
1072 @samp{\n} for newline or @samp{\241} using an octal character code, are
1075 @item String Substitution
1076 See `global substitution'.
1078 @item Syntax Highlighting
1082 The syntax table tells Emacs which characters are part of a word,
1083 which characters balance each other like parentheses, etc.
1087 Super is the name of a modifier bit which a keyboard input character may
1088 have. To make a character Super, type it while holding down the
1089 @key{SUPER} key. Such characters are given names that start with
1090 @kbd{Super-} (usually written @kbd{s-} for short). @xref{User Input,
1094 Suspending Emacs means stopping it temporarily and returning control
1095 to its parent process, which is usually a shell. Unlike killing a job
1096 (q.v.@:), you can later resume the suspended Emacs job without losing
1097 your buffers, unsaved edits, undo history, etc. @xref{Exiting}.
1100 A tags table is a file that serves as an index to the function
1101 definitions in one or more other files. @xref{Tags}.
1103 @item Termscript File
1104 A termscript file contains a record of all characters sent by Emacs to
1105 the terminal. It is used for tracking down bugs in Emacs redisplay.
1106 Emacs does not make a termscript file unless you tell it to.
1110 Two meanings (@pxref{Text}):
1114 Data consisting of a sequence of characters, as opposed to binary
1115 numbers, images, graphics commands, executable programs, and the like.
1116 The contents of an Emacs buffer are always text in this sense.
1118 Data consisting of written human language, as opposed to programs,
1119 or following the stylistic conventions of human language.
1122 @item Text-only Terminal
1123 A text-only terminal is a display that is limited to displaying text in
1124 character units. Such a terminal cannot control individual pixels it
1125 displays. Emacs supports a subset of display features on text-only
1129 The tool bar is a line (sometimes multiple lines) of icons at the top
1130 of an Emacs frame. Clicking on one of these icons executes a command.
1131 You can think of this as a graphical relative of the menu bar (q.v.@:).
1135 Tooltips are small windows displaying a help echo (q.v.@:) text that
1136 explains parts of the display, lists useful options available via mouse
1137 clicks, etc. @xref{Tooltips}.
1140 Top level is the normal state of Emacs, in which you are editing the
1141 text of the file you have visited. You are at top level whenever you
1142 are not in a recursive editing level (q.v.@:) or the minibuffer
1143 (q.v.@:), and not in the middle of a command. You can get back to top
1144 level by aborting (q.v.@:) and quitting (q.v.@:). @xref{Quitting}.
1147 Transposing two units of text means putting each one into the place
1148 formerly occupied by the other. There are Emacs commands to transpose
1149 two adjacent characters, words, sexps (q.v.@:) or lines
1150 (@pxref{Transpose}).
1153 Truncating text lines in the display means leaving out any text on a
1154 line that does not fit within the right margin of the window
1155 displaying it. See also `continuation line.'
1156 @xref{Basic,Truncation,Basic Editing}.
1159 See `text-only terminal.'
1162 Undoing means making your previous editing go in reverse, bringing
1163 back the text that existed earlier in the editing session.
1167 A user option is a variable (q.v.@:) that exists so that you can customize
1168 Emacs by setting it to a new value. @xref{Variables}.
1171 A variable is an object in Lisp that can store an arbitrary value.
1172 Emacs uses some variables for internal purposes, and has others (known
1173 as `user options' (q.v.@:)) just so that you can set their values to
1174 control the behavior of Emacs. The variables used in Emacs that you
1175 are likely to be interested in are listed in the Variables Index in
1176 this manual. @xref{Variables}, for information on variables.
1178 @item Version Control
1179 Version control systems keep track of multiple versions of a source file.
1180 They provide a more powerful alternative to keeping backup files (q.v.@:).
1181 @xref{Version Control}.
1184 Visiting a file means loading its contents into a buffer (q.v.@:)
1185 where they can be edited. @xref{Visiting}.
1188 Whitespace is any run of consecutive formatting characters (space,
1189 tab, newline, and backspace).
1192 Widening is removing any restriction (q.v.@:) on the current buffer;
1193 it is the opposite of narrowing (q.v.@:). @xref{Narrowing}.
1196 Emacs divides a frame (q.v.@:) into one or more windows, each of which
1197 can display the contents of one buffer (q.v.@:) at any time.
1198 @xref{Screen}, for basic information on how Emacs uses the screen.
1199 @xref{Windows}, for commands to control the use of windows. Some
1200 other editors use the term ``window'' for what we call a `frame'
1207 Word search is searching for a sequence of words, considering the
1208 punctuation between them as insignificant. @xref{Word Search}.
1211 WYSIWYG stands for ``What you see is what you get.'' Emacs generally
1212 provides WYSIWYG editing for files of characters; in Enriched mode
1213 (@pxref{Formatted Text}), it provides WYSIWYG editing for files that
1214 include text formatting information.
1217 Yanking means reinserting text previously killed. It can be used to
1218 undo a mistaken kill, or for copying or moving text. Some other
1219 systems call this ``pasting.'' @xref{Yanking}.