1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985,86,87,93,94,95,1997,2001 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 a given maximum width.
48 Auto saving is the practice of saving the contents of an Emacs buffer in
49 a specially-named file, so that the information will not be lost if the
50 buffer is lost due to a system error or user error. @xref{Auto Save}.
53 Emacs automatically loads Lisp libraries when a Lisp program requests a
54 function or a variable from those libraries. This is called
55 `autoloading'. @xref{Lisp Libraries}.
58 A backtrace is a trace of a series of function calls showing how a
59 program arrived to a certain point. It is used mainly for finding and
60 correcting bugs (q.v.@:). Emacs can display a backtrace when it signals
61 an error or when you type @kbd{C-g} (see `quitting'). @xref{Checklist}.
64 A backup file records the contents that a file had before the current
65 editing session. Emacs makes backup files automatically to help you
66 track down or cancel changes you later regret making. @xref{Backup}.
68 @item Balance Parentheses
69 Emacs can balance parentheses (or other matching delimiters) either
70 manually or automatically. You do manual balancing with the commands
71 to move over parenthetical groupings (@pxref{Moving by Parens}).
72 Automatic balancing works by blinking or highlighting the delimiter
73 that matches the one you just inserted (@pxref{Matching,,Matching
76 @item Balanced Expressions
77 A balanced expression is a syntactically recognizable expression, such
78 as a symbol, number, string constant, block, or parenthesized expression
79 in C. @xref{Expressions,Balanced Expressions}.
85 A base buffer is a buffer whose text is shared by an indirect buffer
89 To bind a key sequence means to give it a binding (q.v.@:).
93 A key sequence gets its meaning in Emacs by having a binding, which is a
94 command (q.v.@:), a Lisp function that is run when the user types that
95 sequence. @xref{Commands,Binding}. Customization often involves
96 rebinding a character to a different command function. The bindings of
97 all key sequences are recorded in the keymaps (q.v.@:). @xref{Keymaps}.
100 Blank lines are lines that contain only whitespace. Emacs has several
101 commands for operating on the blank lines in the buffer.
104 Bookmarks are akin to registers (q.v.@:) in that they record positions
105 in buffers to which you can return later. Unlike registers, bookmarks
106 persist between Emacs sessions.
109 The buffer is the basic editing unit; one buffer corresponds to one text
110 being edited. You can have several buffers, but at any time you are
111 editing only one, the `current buffer,' though several can be visible
112 when you are using multiple windows (q.v.@:). Most buffers are visiting
113 (q.v.@:) some file. @xref{Buffers}.
115 @item Buffer Selection History
116 Emacs keeps a buffer selection history which records how recently each
117 Emacs buffer has been selected. This is used for choosing a buffer to
118 select. @xref{Buffers}.
121 A bug is an incorrect or unreasonable behavior of a program, or
122 inaccurate or confusing documentation. Emacs developers treat bug
123 reports, both in Emacs code and its documentation, very seriously and
124 ask you to report any bugs you find. @xref{Bugs}.
126 @item Button Down Event
127 A button down event is the kind of input event generated right away when
128 you press down on a mouse button. @xref{Mouse Buttons}.
134 @kbd{C-} in the name of a character is an abbreviation for Control.
135 @xref{User Input,C-}.
138 @kbd{C-M-} in the name of a character is an abbreviation for
139 Control-Meta. @xref{User Input,C-M-}.
141 @item Case Conversion
142 Case conversion means changing text from upper case to lower case or
143 vice versa. @xref{Case}, for the commands for case conversion.
146 Characters form the contents of an Emacs buffer; see @ref{Text
147 Characters}. Also, key sequences (q.v.@:) are usually made up of
148 characters (though they may include other input events as well).
152 Emacs supports a number of character sets, each of which represents a
153 particular alphabet or script. @xref{International}.
155 @item Character Terminal
156 See `text-only terminal.'
159 A click event is the kind of input event generated when you press a
160 mouse button and release it without moving the mouse. @xref{Mouse Buttons}.
163 A clipboard is a buffer provided by the window system for transferring
164 text between applications. On the X Window system, the clipboard is
165 provided in addition to the primary selection (q.v.@:); on MS-Windows,
166 the clipboard is used @emph{instead} of the primary selection.
170 A coding system is an encoding for representing text characters in a
171 file or in a stream of information. Emacs has the ability to convert
172 text to or from a variety of coding systems when reading or writing it.
173 @xref{Coding Systems}.
176 A command is a Lisp function specially defined to be able to serve as a
177 key binding in Emacs. When you type a key sequence (q.v.@:), its
178 binding (q.v.@:) is looked up in the relevant keymaps (q.v.@:) to find
179 the command to run. @xref{Commands}.
181 @item Command History
182 See `minibuffer history.'
185 A command name is the name of a Lisp symbol which is a command
186 (@pxref{Commands}). You can invoke any command by its name using
187 @kbd{M-x} (@pxref{M-x,M-x,Running Commands by Name}).
190 A comment is text in a program which is intended only for humans reading
191 the program, and which is marked specially so that it will be ignored
192 when the program is loaded or compiled. Emacs offers special commands
193 for creating, aligning and killing comments. @xref{Comments}.
196 Common Lisp is a dialect of Lisp (q.v.@:) much larger and more powerful
197 than Emacs Lisp. Emacs provides a subset of Common Lisp in the CL
198 package. @xref{Common Lisp,,, cl, Common Lisp Extensions}.
201 Compilation is the process of creating an executable program from source
202 code. Emacs has commands for compiling files of Emacs Lisp code
203 (@pxref{Byte Compilation,,, elisp, the Emacs Lisp
204 Reference Manual}) and programs in C and other languages
205 (@pxref{Compilation}).
208 A complete key is a key sequence which fully specifies one action to be
209 performed by Emacs. For example, @kbd{X} and @kbd{C-f} and @kbd{C-x m}
210 are complete keys. Complete keys derive their meanings from being bound
211 (q.v.@:) to commands (q.v.@:). Thus, @kbd{X} is conventionally bound to
212 a command to insert @samp{X} in the buffer; @kbd{C-x m} is
213 conventionally bound to a command to begin composing a mail message.
217 Completion is what Emacs does when it automatically fills out an
218 abbreviation for a name into the entire name. Completion is done for
219 minibuffer (q.v.@:) arguments when the set of possible valid inputs
220 is known; for example, on command names, buffer names, and
221 file names. Completion occurs when @key{TAB}, @key{SPC} or @key{RET}
222 is typed. @xref{Completion}.@refill
224 @item Continuation Line
225 When a line of text is longer than the width of the window, it
226 takes up more than one screen line when displayed. We say that the
227 text line is continued, and all screen lines used for it after the
228 first are called continuation lines. @xref{Basic,Continuation,Basic
229 Editing}. A related Emacs feature is `filling' (q.v.@:).
231 @item Control Character
232 A control character is a character that you type by holding down the
233 @key{CTRL} key. Some control characters also have their own keys, so
234 that you can type them without using @key{CTRL}. For example,
235 @key{RET}, @key{TAB}, @key{ESC} and @key{DEL} are all control
236 characters. @xref{User Input}.
239 A copyleft is a notice giving the public legal permission to
240 redistribute a program or other work of art. Copylefts are used by
241 left-wing programmers to promote freedom and cooperation, just as
242 copyrights are used by right-wing programmers to gain power over other
245 The particular form of copyleft used by the GNU project is called the
246 GNU General Public License. @xref{Copying}.
249 The current buffer in Emacs is the Emacs buffer on which most editing
250 commands operate. You can select any Emacs buffer as the current one.
254 The current line is a line point is on (@pxref{Point}).
256 @item Current Paragraph
257 The current paragraph is the paragraph that point is in. If point is
258 between two paragraphs, the current paragraph is the one that follows
259 point. @xref{Paragraphs}.
262 The current defun is the defun (q.v.@:) that point is in. If point is
263 between defuns, the current defun is the one that follows point.
267 The cursor is the rectangle on the screen which indicates the position
268 called point (q.v.@:) at which insertion and deletion takes place.
269 The cursor is on or under the character that follows point. Often
270 people speak of `the cursor' when, strictly speaking, they mean
271 `point.' @xref{Basic,Cursor,Basic Editing}.
274 Customization is making minor changes in the way Emacs works. It is
275 often done by setting variables (@pxref{Variables}) or by rebinding
276 key sequences (@pxref{Keymaps}).
278 @cindex cut and paste
280 See `killing' and `yanking.'
282 @item Default Argument
283 The default for an argument is the value that will be assumed if you
284 do not specify one. When the minibuffer is used to read an argument,
285 the default argument is used if you just type @key{RET}.
289 A default is the value that is used for a certain purpose if and when
290 you do not specify a value to use.
292 @item Default Directory
293 When you specify a file name that does not start with @samp{/} or @samp{~},
294 it is interpreted relative to the current buffer's default directory.
295 (On MS-Windows and MS-DOS, file names which start with a drive letter
296 @samp{@var{x}:} are treated as absolute, not relative.)
297 @xref{Minibuffer File,Default Directory}.
300 A defun is a major definition at the top level in a program. The name
301 `defun' comes from Lisp, where most such definitions use the construct
302 @code{defun}. @xref{Defuns}.
305 @key{DEL} is a character that runs the command to delete one character of
306 text. @xref{Basic,DEL,Basic Editing}.
309 Deletion means erasing text without copying it into the kill ring
310 (q.v.@:). The alternative is killing (q.v.@:). @xref{Killing,Deletion}.
312 @item Deletion of Files
313 Deleting a file means erasing it from the file system.
314 @xref{Misc File Ops,Misc File Ops,Miscellaneous File Operations}.
316 @item Deletion of Messages
317 Deleting a message means flagging it to be eliminated from your mail
318 file. Until you expunge (q.v.@:) the Rmail file, you can still undelete
319 the messages you have deleted. @xref{Rmail Deletion}.
321 @item Deletion of Windows
322 Deleting a window means eliminating it from the screen. Other windows
323 expand to use up the space. The deleted window can never come back,
324 but no actual text is thereby lost. @xref{Windows}.
327 File directories are named collections in the file system, within which
328 you can place individual files or subdirectories. @xref{Directories}.
331 Dired is the Emacs facility that displays the contents of a file
332 directory and allows you to ``edit the directory,'' performing
333 operations on the files in the directory. @xref{Dired}.
335 @item Disabled Command
336 A disabled command is one that you may not run without special
337 confirmation. The usual reason for disabling a command is that it is
338 confusing for beginning users. @xref{Disabling}.
341 Short for `button down event' (q.v.@:).
344 A drag event is the kind of input event generated when you press a mouse
345 button, move the mouse, and then release the button. @xref{Mouse
349 A dribble file is a file into which Emacs writes all the characters that
350 the user types on the keyboard. Dribble files are used to make a record
351 for debugging Emacs bugs. Emacs does not make a dribble file unless you
352 tell it to. @xref{Bugs}.
355 The echo area is the bottom line of the screen, used for echoing the
356 arguments to commands, for asking questions, and showing brief messages
357 (including error messages). The messages are stored in the buffer
358 @samp{*Messages*} so you can review them later. @xref{Echo Area}.
361 Echoing is acknowledging the receipt of commands by displaying them (in
362 the echo area). Emacs never echoes single-character key sequences;
363 longer key sequences echo only if you pause while typing them.
366 We say that a character is electric if it is normally self-inserting
367 (q.v.@:), but the current major mode (q.v.@:) redefines it to do something
368 else as well. For example, some programming language major modes define
369 particular delimiter characters to reindent the line or insert one or
370 more newlines in addition to self-insertion.
373 End of line is a character or a sequence of characters that indicate
374 the end of a text line. On GNU and Unix systems, this is a newline
375 (q.v.@:), but other systems have other conventions. @xref{Coding
376 Systems,end-of-line}. Emacs can recognize several end-of-line
377 conventions in files and convert between them.
379 @item Environment Variable
380 An environment variable is one of a collection of variables stored by
381 the operating system, each one having a name and a value. Emacs can
382 access environment variables set by its parent shell, and it can set
383 variables in the environment it passes to programs it invokes.
390 An error occurs when an Emacs command cannot execute in the current
391 circumstances. When an error occurs, execution of the command stops
392 (unless the command has been programmed to do otherwise) and Emacs
393 reports the error by displaying an error message (q.v.@:). Type-ahead
394 is discarded. Then Emacs is ready to read another editing command.
397 An error message is a single line of output displayed by Emacs when the
398 user asks for something impossible to do (such as, killing text
399 forward when point is at the end of the buffer). They appear in the
400 echo area, accompanied by a beep.
403 @key{ESC} is a character used as a prefix for typing Meta characters on
404 keyboards lacking a @key{META} key. Unlike the @key{META} key (which,
405 like the @key{SHIFT} key, is held down while another character is
406 typed), you press the @key{ESC} key as you would press a letter key, and
407 it applies to the next character you type.
410 See `balanced expression.'
413 Expunging an Rmail file or Dired buffer or a Gnus newsgroup buffer is an
414 operation that truly discards the messages or files you have previously
415 flagged for deletion.
418 A face is a style of displaying characters. It specifies attributes
419 such as font family and size, foreground and background colors,
420 underline and strike-through, background stipple, etc. Emacs provides
421 features to associate specific faces with portions of buffer text, in
422 order to display that text as specified by the face attributes.
425 Emacs uses file locking to notice when two different users
426 start to edit one file at the same time. @xref{Interlocking}.
429 A file name is a name that refers to a file. File names may be relative
430 or absolute; the meaning of a relative file name depends on the current
431 directory, but an absolute file name refers to the same file regardless
432 of which directory is current. On GNU and Unix systems, an absolute
433 file name starts with a slash (the root directory) or with @samp{~/} or
434 @samp{~@var{user}/} (a home directory). On MS-Windows/MS-DOS, and
435 absolute file name can also start with a drive letter and a colon
438 Some people use the term ``pathname'' for file names, but we do not;
439 we use the word ``path'' only in the term ``search path'' (q.v.@:).
441 @item File-Name Component
442 A file-name component names a file directly within a particular
443 directory. On GNU and Unix systems, a file name is a sequence of
444 file-name components, separated by slashes. For example, @file{foo/bar}
445 is a file name containing two components, @samp{foo} and @samp{bar}; it
446 refers to the file named @samp{bar} in the directory named @samp{foo} in
447 the current directory. MS-DOS/MS-Windows file names can also use
448 backslashes to separate components, as in @file{foo\bar}.
451 The fill prefix is a string that should be expected at the beginning
452 of each line when filling is done. It is not regarded as part of the
453 text to be filled. @xref{Filling}.
456 Filling text means shifting text between consecutive lines so that all
457 the lines are approximately the same length. @xref{Filling}. Some
458 other editors call this feature `line wrapping.'
461 Font Lock is a mode that highlights parts of buffer text according to
462 its syntax. @xref{Font Lock}.
465 A fontset is a named collection of fonts. A fontset specification lists
466 character sets and which font to use to display each of them. Fontsets
467 make it easy to change several fonts at once by specifying the name of a
468 fontset, rather than changing each font separately. @xref{Fontsets}.
471 Formatted text is text that displays with formatting information while
472 you edit. Formatting information includes fonts, colors, and specified
473 margins. @xref{Formatted Text}.
475 @item Formfeed Character
479 A frame is a rectangular cluster of Emacs windows. Emacs starts out
480 with one frame, but you can create more. You can subdivide each frame
481 into Emacs windows (q.v.@:). When you are using a windowing system, all
482 the frames can be visible at the same time. @xref{Frames}. Some
483 other editors use the term ``window'' for this, but in Emacs a window
484 means something else.
487 On windowed displays, there's a narrow portion of the frame (q.v.@:)
488 between the text area and the window's border. Emacs displays the
489 fringe using a special face (q.v.@:) called @code{fringe}.
493 FTP is an acronym for File Transfer Protocol. Emacs uses an FTP client
494 program to provide access to remote files (q.v.@:).
497 A function key is a key on the keyboard that sends input but does not
498 correspond to any character. @xref{Function Keys}.
501 Global means ``independent of the current environment; in effect
502 throughout Emacs.'' It is the opposite of local (q.v.@:). Particular
503 examples of the use of `global' appear below.
506 A global definition of an abbrev (q.v.@:) is effective in all major
507 modes that do not have local (q.v.@:) definitions for the same abbrev.
511 The global keymap (q.v.@:) contains key bindings that are in effect
512 except when overridden by local key bindings in a major mode's local
513 keymap (q.v.@:). @xref{Keymaps}.
515 @item Global Mark Ring
516 The global mark ring records the series of buffers you have recently
517 set a mark (q.v.@:) in. In many cases you can use this to backtrack
518 through buffers you have been editing in, or in which you have found
519 tags (see `tags table'). @xref{Global Mark Ring}.
521 @item Global Substitution
522 Global substitution means replacing each occurrence of one string by
523 another string throughout a large amount of text. @xref{Replace}.
525 @item Global Variable
526 The global value of a variable (q.v.@:) takes effect in all buffers
527 that do not have their own local (q.v.@:) values for the variable.
530 @item Graphic Character
531 Graphic characters are those assigned pictorial images rather than
532 just names. All the non-Meta (q.v.@:) characters except for the
533 Control (q.v.@:) characters are graphic characters. These include
534 letters, digits, punctuation, and spaces; they do not include
535 @key{RET} or @key{ESC}. In Emacs, typing a graphic character inserts
536 that character (in ordinary editing modes). @xref{Basic,,Basic Editing}.
539 Highlighting text means displaying it with a different foreground and/or
540 background color to make it stand out from the rest of the text in the
544 Hardcopy means printed output. Emacs has commands for making printed
545 listings of text in Emacs buffers. @xref{Hardcopy}.
548 @key{HELP} is the Emacs name for @kbd{C-h} or @key{F1}. You can type
549 @key{HELP} at any time to ask what options you have, or to ask what any
550 command does. @xref{Help}.
553 Help echo is a short message displayed in the echo area when the mouse
554 pointer is located on portions of display that require some
555 explanations. Emacs displays help echo for menu items, parts of the
556 mode line, tool-bar buttons, etc. On graphics displays, the messages
557 can be displayed as tooltips (q.v.@:). @xref{Tooltips}.
560 A hook is a list of functions to be called on specific occasions, such
561 as saving a buffer in a file, major mode activation, etc. By
562 customizing the various hooks, you can modify Emacs's behavior without
563 changing any of its code. @xref{Hooks}.
566 Hyper is the name of a modifier bit which a keyboard input character may
567 have. To make a character Hyper, type it while holding down the
568 @key{HYPER} key. Such characters are given names that start with
569 @kbd{Hyper-} (usually written @kbd{H-} for short). @xref{User Input,
573 An inbox is a file in which mail is delivered by the operating system.
574 Rmail transfers mail from inboxes to Rmail files (q.v.@:) in which the
575 mail is then stored permanently or until explicitly deleted.
578 @item Incremental Search
579 Emacs provides an incremental search facility, whereby Emacs searches
580 for the string as you type it. @xref{Incremental Search}.
583 Indentation means blank space at the beginning of a line. Most
584 programming languages have conventions for using indentation to
585 illuminate the structure of the program, and Emacs has special
586 commands to adjust indentation.
589 @item Indirect Buffer
590 An indirect buffer is a buffer that shares the text of another buffer,
591 called its base buffer (q.v.@:). @xref{Indirect Buffers}.
594 Info is the hypertext format used by the GNU project for writing
598 An input event represents, within Emacs, one action taken by the user on
599 the terminal. Input events include typing characters, typing function
600 keys, pressing or releasing mouse buttons, and switching between Emacs
601 frames. @xref{User Input}.
604 An input method is a system for entering non-ASCII text characters by
605 typing sequences of ASCII characters (q.v.@:). @xref{Input Methods}.
608 Insertion means copying text into the buffer, either from the keyboard
609 or from some other place in Emacs.
612 Interlocking is a feature for warning when you start to alter a file
613 that someone else is already editing.
614 @xref{Interlocking,Interlocking,Simultaneous Editing}.
617 See `incremental search.'
620 Justification means adding extra spaces within lines of text to make
621 them extend exactly to a specified width.
622 @xref{Filling,Justification}.
625 Keyboard macros are a way of defining new Emacs commands from
626 sequences of existing ones, with no need to write a Lisp program.
627 @xref{Keyboard Macros}.
629 @cindex keyboard shortcuts
630 @item Keyboard Shortcut
631 A keyboard shortcut is a key sequence (q.v.@:) which invokes a
632 command. What other programs call ``assign a keyboard shortcut''
633 Emacs calls ``bind a key sequence''. See `binding.'
636 A key sequence (key, for short) is a sequence of input events (q.v.@:)
637 that are meaningful as a single unit. If the key sequence is enough to
638 specify one action, it is a complete key (q.v.@:); if it is not enough,
639 it is a prefix key (q.v.@:). @xref{Keys}.
642 The keymap is the data structure that records the bindings (q.v.@:) of
643 key sequences to the commands that they run. For example, the global
644 keymap binds the character @kbd{C-n} to the command function
645 @code{next-line}. @xref{Keymaps}.
647 @item Keyboard Translation Table
648 The keyboard translation table is an array that translates the character
649 codes that come from the terminal into the character codes that make up
650 key sequences. @xref{Keyboard Translations}.
653 The kill ring is where all text you have killed recently is saved.
654 You can reinsert any of the killed text still in the ring; this is
655 called yanking (q.v.@:). @xref{Yanking}.
658 Killing means erasing text and saving it on the kill ring so it can be
659 yanked (q.v.@:) later. Some other systems call this ``cutting.''
660 Most Emacs commands that erase text perform killing, as opposed to
661 deletion (q.v.@:). @xref{Killing}.
664 Killing a job (such as, an invocation of Emacs) means making it cease
665 to exist. Any data within it, if not saved in a file, is lost.
668 @item Language Environment
669 Your choice of language environment specifies defaults for the input
670 method (q.v.@:) and coding system (q.v.@:). @xref{Language
671 Environments}. These defaults are relevant if you edit non-ASCII text
672 (@pxref{International}).
678 Lisp is a programming language. Most of Emacs is written in a dialect
679 of Lisp, called Emacs Lisp, that is extended with special features which
680 make it especially suitable for text editing tasks.
683 A list is, approximately, a text string beginning with an open
684 parenthesis and ending with the matching close parenthesis. In C mode
685 and other non-Lisp modes, groupings surrounded by other kinds of matched
686 delimiters appropriate to the language, such as braces, are also
687 considered lists. Emacs has special commands for many operations on
688 lists. @xref{Moving by Parens}.
691 Local means ``in effect only in a particular context''; the relevant
692 kind of context is a particular function execution, a particular
693 buffer, or a particular major mode. It is the opposite of `global'
694 (q.v.@:). Specific uses of `local' in Emacs terminology appear below.
697 A local abbrev definition is effective only if a particular major mode
698 is selected. In that major mode, it overrides any global definition
699 for the same abbrev. @xref{Abbrevs}.
702 A local keymap is used in a particular major mode; the key bindings
703 (q.v.@:) in the current local keymap override global bindings of the
704 same key sequences. @xref{Keymaps}.
707 A local value of a variable (q.v.@:) applies to only one buffer.
711 @kbd{M-} in the name of a character is an abbreviation for @key{META},
712 one of the modifier keys that can accompany any character.
716 @kbd{M-C-} in the name of a character is an abbreviation for
717 Control-Meta; it means the same thing as @kbd{C-M-}. If your
718 terminal lacks a real @key{META} key, you type a Control-Meta character by
719 typing @key{ESC} and then typing the corresponding Control character.
720 @xref{User Input,C-M-}.
723 @kbd{M-x} is the key sequence which is used to call an Emacs command by
724 name. This is how you run commands that are not bound to key sequences.
725 @xref{M-x,M-x,Running Commands by Name}.
728 Mail means messages sent from one user to another through the computer
729 system, to be read at the recipient's convenience. Emacs has commands for
730 composing and sending mail, and for reading and editing the mail you have
731 received. @xref{Sending Mail}. @xref{Rmail}, for how to read mail.
733 @item Mail Composition Method
734 A mail composition method is a program runnable within Emacs for editing
735 and sending a mail message. Emacs lets you select from several
736 alternative mail composition methods. @xref{Mail Methods}.
739 The Emacs major modes are a mutually exclusive set of options, each of
740 which configures Emacs for editing a certain sort of text. Ideally,
741 each programming language has its own major mode. @xref{Major Modes}.
744 The mark points to a position in the text. It specifies one end of the
745 region (q.v.@:), point being the other end. Many commands operate on
746 all the text from point to the mark. Each buffer has its own mark.
750 The mark ring is used to hold several recent previous locations of the
751 mark, just in case you want to move back to them. Each buffer has its
752 own mark ring; in addition, there is a single global mark ring (q.v.@:).
756 The menu bar is the line at the top of an Emacs frame. It contains
757 words you can click on with the mouse to bring up menus, or you can use
758 a keyboard interface to navigate it. @xref{Menu Bars}.
764 Meta is the name of a modifier bit which a command character may have.
765 It is present in a character if the character is typed with the
766 @key{META} key held down. Such characters are given names that start
767 with @kbd{Meta-} (usually written @kbd{M-} for short). For example,
768 @kbd{M-<} is typed by holding down @key{META} and at the same time
769 typing @kbd{<} (which itself is done, on most terminals, by holding
770 down @key{SHIFT} and typing @kbd{,}). @xref{User Input,Meta}.
773 A Meta character is one whose character code includes the Meta bit.
776 The minibuffer is the window that appears when necessary inside the
777 echo area (q.v.@:), used for reading arguments to commands.
780 @item Minibuffer History
781 The minibuffer history records the text you have specified in the past
782 for minibuffer arguments, so you can conveniently use the same text
783 again. @xref{Minibuffer History}.
786 A minor mode is an optional feature of Emacs which can be switched on
787 or off independently of all other features. Each minor mode has a
788 command to turn it on or off. @xref{Minor Modes}.
790 @item Minor Mode Keymap
791 A minor mode keymap is a keymap that belongs to a minor mode and is
792 active when that mode is enabled. Minor mode keymaps take precedence
793 over the buffer's local keymap, just as the local keymap takes
794 precedence over the global keymap. @xref{Keymaps}.
797 The mode line is the line at the bottom of each window (q.v.@:), giving
798 status information on the buffer displayed in that window. @xref{Mode
801 @item Modified Buffer
802 A buffer (q.v.@:) is modified if its text has been changed since the
803 last time the buffer was saved (or since when it was created, if it
804 has never been saved). @xref{Saving}.
807 Moving text means erasing it from one place and inserting it in
808 another. The usual way to move text by killing (q.v.@:) and then
809 yanking (q.v.@:). @xref{Killing}.
812 MULE refers to the Emacs features for editing multilingual non-ASCII text
813 using multibyte characters (q.v.@:). @xref{International}.
815 @item Multibyte Character
816 A multibyte character is a character that takes up several bytes in a
817 buffer. Emacs uses multibyte characters to represent non-ASCII text,
818 since the number of non-ASCII characters is much more than 256.
819 @xref{International Chars, International Characters}.
822 A named mark is a register (q.v.@:) in its role of recording a
823 location in text so that you can move point to that location.
827 Narrowing means creating a restriction (q.v.@:) that limits editing in
828 the current buffer to only a part of the text in the buffer. Text
829 outside that part is inaccessible to the user until the boundaries are
830 widened again, but it is still there, and saving the file saves it
831 all. @xref{Narrowing}.
834 Control-J characters in the buffer terminate lines of text and are
835 therefore also called newlines. @xref{Text Characters,Newline}.
840 @code{nil} is a value usually interpreted as a logical ``false.'' Its
841 opposite is @code{t}, interpreted as ``true.''
843 @item Numeric Argument
844 A numeric argument is a number, specified before a command, to change
845 the effect of the command. Often the numeric argument serves as a
846 repeat count. @xref{Arguments}.
849 Overwrite mode is a minor mode. When it is enabled, ordinary text
850 characters replace the existing text after point rather than pushing
851 it to the right. @xref{Minor Modes}.
854 A page is a unit of text, delimited by formfeed characters (ASCII
855 control-L, code 014) coming at the beginning of a line. Some Emacs
856 commands are provided for moving over and operating on pages.
860 Paragraphs are the medium-size unit of human-language text. There are
861 special Emacs commands for moving over and operating on paragraphs.
865 We say that certain Emacs commands parse words or expressions in the
866 text being edited. Really, all they know how to do is find the other
867 end of a word or expression. @xref{Syntax}.
870 Point is the place in the buffer at which insertion and deletion
871 occur. Point is considered to be between two characters, not at one
872 character. The terminal's cursor (q.v.@:) indicates the location of
873 point. @xref{Basic,Point,Basic Editing}.
875 @item Prefix Argument
876 See `numeric argument.'
879 A prefix key is a key sequence (q.v.@:) whose sole function is to
880 introduce a set of longer key sequences. @kbd{C-x} is an example of
881 prefix key; any two-character sequence starting with @kbd{C-x} is
882 therefore a legitimate key sequence. @xref{Keys}.
884 @item Primary Rmail File
885 Your primary Rmail file is the file named @samp{RMAIL} in your home
886 directory. That's where Rmail stores your incoming mail, unless you
887 specify a different file name. @xref{Rmail}.
889 @item Primary Selection
890 The primary selection is one particular X selection (q.v.@:); it is the
891 selection that most X applications use for transferring text to and from
894 The Emacs kill commands set the primary selection and the yank command
895 uses the primary selection when appropriate. @xref{Killing}.
898 A prompt is text used to ask the user for input. Displaying a prompt
899 is called prompting. Emacs prompts always appear in the echo area
900 (q.v.@:). One kind of prompting happens when the minibuffer is used to
901 read an argument (@pxref{Minibuffer}); the echoing which happens when
902 you pause in the middle of typing a multi-character key sequence is also
903 a kind of prompting (@pxref{Echo Area}).
906 Query-replace is an interactive string replacement feature provided by
907 Emacs. @xref{Query Replace}.
910 Quitting means canceling a partially typed command or a running
911 command, using @kbd{C-g} (or @kbd{C-@key{BREAK}} on MS-DOS). @xref{Quitting}.
914 Quoting means depriving a character of its usual special significance.
915 The most common kind of quoting in Emacs is with @kbd{C-q}. What
916 constitutes special significance depends on the context and on
917 convention. For example, an ``ordinary'' character as an Emacs command
918 inserts itself; so in this context, a special character is any character
919 that does not normally insert itself (such as @key{DEL}, for example),
920 and quoting it makes it insert itself as if it were not special. Not
921 all contexts allow quoting. @xref{Basic,Quoting,Basic Editing}.
923 @item Quoting File Names
924 Quoting a file name turns off the special significance of constructs
925 such as @samp{$}, @samp{~} and @samp{:}. @xref{Quoted File Names}.
927 @item Read-Only Buffer
928 A read-only buffer is one whose text you are not allowed to change.
929 Normally Emacs makes buffers read-only when they contain text which
930 has a special significance to Emacs; for example, Dired buffers.
931 Visiting a file that is write-protected also makes a read-only buffer.
935 A rectangle consists of the text in a given range of columns on a given
936 range of lines. Normally you specify a rectangle by putting point at
937 one corner and putting the mark at the diagonally opposite corner.
940 @item Recursive Editing Level
941 A recursive editing level is a state in which part of the execution of
942 a command involves asking the user to edit some text. This text may
943 or may not be the same as the text to which the command was applied.
944 The mode line indicates recursive editing levels with square brackets
945 (@samp{[} and @samp{]}). @xref{Recursive Edit}.
948 Redisplay is the process of correcting the image on the screen to
949 correspond to changes that have been made in the text being edited.
950 @xref{Screen,Redisplay}.
953 See `regular expression.'
956 The region is the text between point (q.v.@:) and the mark (q.v.@:).
957 Many commands operate on the text of the region. @xref{Mark,Region}.
960 Registers are named slots in which text or buffer positions or
961 rectangles can be saved for later use. @xref{Registers}. A related
962 Emacs feature is `bookmarks' (q.v.@:).
964 @item Regular Expression
965 A regular expression is a pattern that can match various text strings;
966 for example, @samp{a[0-9]+} matches @samp{a} followed by one or more
967 digits. @xref{Regexps}.
970 A remote file is a file that is stored on a system other than your own.
971 Emacs can access files on other computers provided that they are
972 connected to the same network as your machine, and (obviously) that
973 you have a supported method to gain access to those files.
977 See `numeric argument.'
980 See `global substitution.'
983 A buffer's restriction is the amount of text, at the beginning or the
984 end of the buffer, that is temporarily inaccessible. Giving a buffer a
985 nonzero amount of restriction is called narrowing (q.v.@:); removing
986 a restriction is called widening (q.v.@:). @xref{Narrowing}.
989 @key{RET} is a character that in Emacs runs the command to insert a
990 newline into the text. It is also used to terminate most arguments
991 read in the minibuffer (q.v.@:). @xref{User Input,Return}.
994 Reverting means returning to the original state. Emacs lets you
995 revert a buffer by re-reading its file from disk. @xref{Reverting}.
998 An Rmail file is a file containing text in a special format used by
999 Rmail for storing mail. @xref{Rmail}.
1002 Saving a buffer means copying its text into the file that was visited
1003 (q.v.@:) in that buffer. This is the way text in files actually gets
1004 changed by your Emacs editing. @xref{Saving}.
1007 A scroll bar is a tall thin hollow box that appears at the side of a
1008 window. You can use mouse commands in the scroll bar to scroll the
1009 window. The scroll bar feature is supported only under windowing
1010 systems. @xref{Scroll Bars}.
1013 Scrolling means shifting the text in the Emacs window so as to see a
1014 different part of the buffer. @xref{Display,Scrolling}.
1017 Searching means moving point to the next occurrence of a specified
1018 string or the next match for a specified regular expression.
1022 A search path is a list of directory names, to be used for searching for
1023 files for certain purposes. For example, the variable @code{load-path}
1024 holds a search path for finding Lisp library files. @xref{Lisp Libraries}.
1026 @item Secondary Selection
1027 The secondary selection is one particular X selection; some X
1028 applications can use it for transferring text to and from other
1029 applications. Emacs has special mouse commands for transferring text
1030 using the secondary selection. @xref{Secondary Selection}.
1033 Selecting a buffer means making it the current (q.v.@:) buffer.
1034 @xref{Buffers,Selecting}.
1037 Windowing systems allow an application program to specify
1038 selections whose values are text. A program can also read the
1039 selections that other programs have set up. This is the principal way
1040 of transferring text between window applications. Emacs has commands to
1041 work with the primary (q.v.@:) selection and the secondary (q.v.@:)
1042 selection, and also with the clipboard (q.v.@:).
1044 @item Self-Documentation
1045 Self-documentation is the feature of Emacs which can tell you what any
1046 command does, or give you a list of all commands related to a topic
1047 you specify. You ask for self-documentation with the help character,
1048 @kbd{C-h}. @xref{Help}.
1050 @item Self-Inserting Character
1051 A character is self-inserting if typing that character inserts that
1052 character in the buffer. Ordinary printing and whitespace characters
1053 are self-inserting in Emacs, except in certain special major modes.
1056 Emacs has commands for moving by or killing by sentences.
1060 A sexp (short for ``s-expression'') is the basic syntactic unit of
1061 Lisp in its textual form: either a list, or Lisp atom. Sexps are also
1062 the balanced expressions (q.v.@:) of the Lisp language; this is why
1063 the commands for editing balanced expressions have `sexp' in their
1064 name. @xref{Expressions,Sexps}.
1066 @item Simultaneous Editing
1067 Simultaneous editing means two users modifying the same file at once.
1068 Simultaneous editing, if not detected, can cause one user to lose his
1069 or her work. Emacs detects all cases of simultaneous editing, and
1070 warns one of the users to investigate.
1071 @xref{Interlocking,Interlocking,Simultaneous Editing}.
1074 Speedbar is a special tall frame that provides fast access to Emacs
1075 buffers, functions within those buffers, Info nodes, and other
1076 interesting parts of text within Emacs. @xref{Speedbar}.
1078 @item Spell Checking
1079 Spell checking means checking correctness of the written form of each
1080 one of the words in a text. Emacs uses the Ispell spelling-checker
1081 program to check the spelling of parts of a buffer via a convenient user
1082 interface. @xref{Spelling}.
1085 A string is a kind of Lisp data object which contains a sequence of
1086 characters. Many Emacs variables are intended to have strings as
1087 values. The Lisp syntax for a string consists of the characters in the
1088 string with a @samp{"} before and another @samp{"} after. A @samp{"}
1089 that is part of the string must be written as @samp{\"} and a @samp{\}
1090 that is part of the string must be written as @samp{\\}. All other
1091 characters, including newline, can be included just by writing them
1092 inside the string; however, backslash sequences as in C, such as
1093 @samp{\n} for newline or @samp{\241} using an octal character code, are
1096 @item String Substitution
1097 See `global substitution'.
1099 @item Syntax Highlighting
1103 The syntax table tells Emacs which characters are part of a word,
1104 which characters balance each other like parentheses, etc.
1108 Super is the name of a modifier bit which a keyboard input character may
1109 have. To make a character Super, type it while holding down the
1110 @key{SUPER} key. Such characters are given names that start with
1111 @kbd{Super-} (usually written @kbd{s-} for short). @xref{User Input,
1115 Suspending Emacs means stopping it temporarily and returning control
1116 to its parent process, which is usually a shell. Unlike killing a job
1117 (q.v.@:), you can later resume the suspended Emacs job without losing
1118 your buffers, unsaved edits, undo history, etc. @xref{Exiting}.
1121 A tags table is a file that serves as an index to the function
1122 definitions in one or more other files. @xref{Tags}.
1124 @item Termscript File
1125 A termscript file contains a record of all characters sent by Emacs to
1126 the terminal. It is used for tracking down bugs in Emacs redisplay.
1127 Emacs does not make a termscript file unless you tell it to.
1131 `Text' has two meanings (@pxref{Text}):
1135 Data consisting of a sequence of characters, as opposed to binary
1136 numbers, executable programs, and the like. The basic contents of an
1137 Emacs buffer (aside from the text properties, q.v.@:) are always text
1140 Data consisting of written human language, as opposed to programs,
1141 or following the stylistic conventions of human language.
1144 @item Text-only Terminal
1145 A text-only terminal is a display that is limited to displaying text in
1146 character units. Such a terminal cannot control individual pixels it
1147 displays. Emacs supports a subset of display features on text-only
1150 @item Text Properties
1151 Text properties are annotations recorded for particular characters in
1152 the buffer. Images in the buffer are recorded as text properties;
1153 they also specify formatting information. @xref{Editing Format Info}.
1156 The tool bar is a line (sometimes multiple lines) of icons at the top
1157 of an Emacs frame. Clicking on one of these icons executes a command.
1158 You can think of this as a graphical relative of the menu bar (q.v.@:).
1162 Tooltips are small windows displaying a help echo (q.v.@:) text that
1163 explains parts of the display, lists useful options available via mouse
1164 clicks, etc. @xref{Tooltips}.
1167 Top level is the normal state of Emacs, in which you are editing the
1168 text of the file you have visited. You are at top level whenever you
1169 are not in a recursive editing level (q.v.@:) or the minibuffer
1170 (q.v.@:), and not in the middle of a command. You can get back to top
1171 level by aborting (q.v.@:) and quitting (q.v.@:). @xref{Quitting}.
1174 Transposing two units of text means putting each one into the place
1175 formerly occupied by the other. There are Emacs commands to transpose
1176 two adjacent characters, words, balanced expressions (q.v.@:) or lines
1177 (@pxref{Transpose}).
1180 Truncating text lines in the display means leaving out any text on a
1181 line that does not fit within the right margin of the window
1182 displaying it. See also `continuation line.'
1183 @xref{Basic,Truncation,Basic Editing}.
1186 See `text-only terminal.'
1189 Undoing means making your previous editing go in reverse, bringing
1190 back the text that existed earlier in the editing session.
1194 A user option is a variable (q.v.@:) that exists so that you can customize
1195 Emacs by setting it to a new value. @xref{Variables}.
1198 A variable is an object in Lisp that can store an arbitrary value.
1199 Emacs uses some variables for internal purposes, and has others (known
1200 as `user options' (q.v.@:)) just so that you can set their values to
1201 control the behavior of Emacs. The variables used in Emacs that you
1202 are likely to be interested in are listed in the Variables Index in
1203 this manual (@pxref{Variable Index}). @xref{Variables}, for
1204 information on variables.
1206 @item Version Control
1207 Version control systems keep track of multiple versions of a source file.
1208 They provide a more powerful alternative to keeping backup files (q.v.@:).
1209 @xref{Version Control}.
1212 Visiting a file means loading its contents into a buffer (q.v.@:)
1213 where they can be edited. @xref{Visiting}.
1216 Whitespace is any run of consecutive formatting characters (space,
1217 tab, newline, and backspace).
1220 Widening is removing any restriction (q.v.@:) on the current buffer;
1221 it is the opposite of narrowing (q.v.@:). @xref{Narrowing}.
1224 Emacs divides a frame (q.v.@:) into one or more windows, each of which
1225 can display the contents of one buffer (q.v.@:) at any time.
1226 @xref{Screen}, for basic information on how Emacs uses the screen.
1227 @xref{Windows}, for commands to control the use of windows. Some
1228 other editors use the term ``window'' for what we call a `frame'
1235 Word search is searching for a sequence of words, considering the
1236 punctuation between them as insignificant. @xref{Word Search}.
1239 WYSIWYG stands for ``What you see is what you get.'' Emacs generally
1240 provides WYSIWYG editing for files of characters; in Enriched mode
1241 (@pxref{Formatted Text}), it provides WYSIWYG editing for files that
1242 include text formatting information.
1245 Yanking means reinserting text previously killed. It can be used to
1246 undo a mistaken kill, or for copying or moving text. Some other
1247 systems call this ``pasting.'' @xref{Yanking}.