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 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 manually or automatically. Manual
70 balancing is done by the commands to move over balanced expressions
71 (@pxref{Lists}). Automatic balancing is done by blinking or
72 highlighting the parenthesis that matches one just inserted
73 (@pxref{Matching,,Matching Parens}).
79 A base buffer is a buffer whose text is shared by an indirect buffer
83 To bind a key sequence means to give it a binding (q.v.@:).
87 A key sequence gets its meaning in Emacs by having a binding, which is a
88 command (q.v.@:), a Lisp function that is run when the user types that
89 sequence. @xref{Commands,Binding}. Customization often involves
90 rebinding a character to a different command function. The bindings of
91 all key sequences are recorded in the keymaps (q.v.@:). @xref{Keymaps}.
94 Blank lines are lines that contain only whitespace. Emacs has several
95 commands for operating on the blank lines in the buffer.
98 Bookmarks are akin to registers (q.v.@:) in that they record positions
99 in buffers to which you can return later. Unlike registers, bookmarks
100 persist between Emacs sessions.
103 The buffer is the basic editing unit; one buffer corresponds to one text
104 being edited. You can have several buffers, but at any time you are
105 editing only one, the `current buffer,' though several can be visible
106 when you are using multiple windows (q.v.@:). Most buffers are visiting
107 (q.v.@:) some file. @xref{Buffers}.
109 @item Buffer Selection History
110 Emacs keeps a buffer selection history which records how recently each
111 Emacs buffer has been selected. This is used for choosing a buffer to
112 select. @xref{Buffers}.
115 A bug is an incorrect or unreasonable behavior of a program, or
116 inaccurate or confusing documentation. Emacs developers treat bug
117 reports, both in Emacs code and its documentation, very seriously and
118 ask you to report any bugs you find. @xref{Bugs}.
120 @item Button Down Event
121 A button down event is the kind of input event generated right away when
122 you press a mouse button. @xref{Mouse Buttons}.
128 @kbd{C-} in the name of a character is an abbreviation for Control.
129 @xref{User Input,C-}.
132 @kbd{C-M-} in the name of a character is an abbreviation for
133 Control-Meta. @xref{User Input,C-M-}.
135 @item Case Conversion
136 Case conversion means changing text from upper case to lower case or
137 vice versa. @xref{Case}, for the commands for case conversion.
140 Characters form the contents of an Emacs buffer; see @ref{Text
141 Characters}. Also, key sequences (q.v.@:) are usually made up of
142 characters (though they may include other input events as well).
146 Emacs supports a number of character sets, each of which represents a
147 particular alphabet or script. @xref{International}.
149 @item Character Terminal
150 See `text-only terminal.'
153 A click event is the kind of input event generated when you press a
154 mouse button and release it without moving the mouse. @xref{Mouse Buttons}.
157 A clipboard is a buffer provided by the window system for transferring
158 text between applications. On the X Window system, the clipboard is
159 provided in addition to the primary selection (q.v.@:); on MS-Windows,
160 the clipboard is used @emph{instead} of the primary selection.
164 A coding system is an encoding for representing text characters in a
165 file or in a stream of information. Emacs has the ability to convert
166 text to or from a variety of coding systems when reading or writing it.
167 @xref{Coding Systems}.
170 A command is a Lisp function specially defined to be able to serve as a
171 key binding in Emacs. When you type a key sequence (q.v.@:), its
172 binding (q.v.@:) is looked up in the relevant keymaps (q.v.@:) to find
173 the command to run. @xref{Commands}.
175 @item Command History
176 See `minibuffer history.'
179 A command name is the name of a Lisp symbol which is a command
180 (@pxref{Commands}). You can invoke any command by its name using
181 @kbd{M-x} (@pxref{M-x,M-x,Running Commands by Name}).
184 A comment is text in a program which is intended only for humans reading
185 the program, and which is marked specially so that it will be ignored
186 when the program is loaded or compiled. Emacs offers special commands
187 for creating, aligning and killing comments. @xref{Comments}.
190 Common Lisp is a dialect of Lisp (q.v.@:) much larger and more powerful
191 than Emacs Lisp. Emacs provides a subset of Common Lisp in the CL
192 package. @xref{Common Lisp,,, cl, Common Lisp Extensions}.
195 Compilation is the process of creating an executable program from source
196 code. Emacs has commands for compiling files of Emacs Lisp code
197 (@pxref{Byte Compilation,,, elisp, the Emacs Lisp
198 Reference Manual}) and programs in C and other languages
199 (@pxref{Compilation}).
202 A complete key is a key sequence which fully specifies one action to be
203 performed by Emacs. For example, @kbd{X} and @kbd{C-f} and @kbd{C-x m}
204 are complete keys. Complete keys derive their meanings from being bound
205 (q.v.@:) to commands (q.v.@:). Thus, @kbd{X} is conventionally bound to
206 a command to insert @samp{X} in the buffer; @kbd{C-x m} is
207 conventionally bound to a command to begin composing a mail message.
211 Completion is what Emacs does when it automatically fills out an
212 abbreviation for a name into the entire name. Completion is done for
213 minibuffer (q.v.@:) arguments when the set of possible valid inputs
214 is known; for example, on command names, buffer names, and
215 file names. Completion occurs when @key{TAB}, @key{SPC} or @key{RET}
216 is typed. @xref{Completion}.@refill
218 @item Continuation Line
219 When a line of text is longer than the width of the window, it
220 takes up more than one screen line when displayed. We say that the
221 text line is continued, and all screen lines used for it after the
222 first are called continuation lines. @xref{Basic,Continuation,Basic
223 Editing}. A related Emacs feature is `filling' (q.v.@:).
225 @item Control Character
226 A control character is a character that you type by holding down the
227 @key{CTRL} key. Some control characters also have their own keys, so
228 that you can type them without using @key{CTRL}. For example,
229 @key{RET}, @key{TAB}, @key{ESC} and @key{DEL} are all control
230 characters. @xref{User Input}.
233 A copyleft is a notice giving the public legal permission to
234 redistribute a program or other work of art. Copylefts are used by
235 left-wing programmers to promote freedom and cooperation, just as
236 copyrights are used by right-wing programmers to gain power over other
239 The particular form of copyleft used by the GNU project is called the
240 GNU General Public License. @xref{Copying}.
243 The current buffer in Emacs is the Emacs buffer on which most editing
244 commands operate. You can select any Emacs buffer as the current one.
248 The current line is a line point is on (@pxref{Point}).
250 @item Current Paragraph
251 The current paragraph is the paragraph that point is in. If point is
252 between paragraphs, the current paragraph is the one that follows point.
256 The current defun is a defun (q.v.@:) that point is in. If point is
257 between defuns, the current defun is the one that follows point.
261 The cursor is the rectangle on the screen which indicates the position
262 called point (q.v.@:) at which insertion and deletion takes place.
263 The cursor is on or under the character that follows point. Often
264 people speak of `the cursor' when, strictly speaking, they mean
265 `point.' @xref{Basic,Cursor,Basic Editing}.
268 Customization is making minor changes in the way Emacs works. It is
269 often done by setting variables (@pxref{Variables}) or by rebinding
270 key sequences (@pxref{Keymaps}).
273 See `killing' and `yanking.'
275 @item Default Argument
276 The default for an argument is the value that will be assumed if you
277 do not specify one. When the minibuffer is used to read an argument,
278 the default argument is used if you just type @key{RET}.
282 A default is the value that is used for a certain purpose if and when
283 you do not specify a value to use.
285 @item Default Directory
286 When you specify a file name that does not start with @samp{/} or @samp{~},
287 it is interpreted relative to the current buffer's default directory.
288 (On MS-Windows and MS-DOS, file names which start with a drive letter
289 @samp{@var{x}:} are treated as absolute, not relative.)
290 @xref{Minibuffer File,Default Directory}.
293 A defun is a list at the top level of parenthesis or bracket structure
294 in a program. It is so named because most such lists in Lisp programs
295 are calls to the Lisp function @code{defun}. @xref{Defuns}.
298 @key{DEL} is a character that runs the command to delete one character of
299 text. @xref{Basic,DEL,Basic Editing}.
302 Deletion means erasing text without copying it into the kill ring
303 (q.v.@:). The alternative is killing (q.v.@:). @xref{Killing,Deletion}.
305 @item Deletion of Files
306 Deleting a file means erasing it from the file system.
307 @xref{Misc File Ops,Misc File Ops,Miscellaneous File Operations}.
309 @item Deletion of Messages
310 Deleting a message means flagging it to be eliminated from your mail
311 file. Until you expunge (q.v.@:) the Rmail file, you can still undelete
312 the messages you have deleted. @xref{Rmail Deletion}.
314 @item Deletion of Windows
315 Deleting a window means eliminating it from the screen. Other windows
316 expand to use up the space. The deleted window can never come back,
317 but no actual text is thereby lost. @xref{Windows}.
320 File directories are named collections in the file system, within which
321 you can place individual files or subdirectories. @xref{Directories}.
324 Dired is the Emacs facility that displays the contents of a file
325 directory and allows you to ``edit the directory,'' performing
326 operations on the files in the directory. @xref{Dired}.
328 @item Disabled Command
329 A disabled command is one that you may not run without special
330 confirmation. The usual reason for disabling a command is that it is
331 confusing for beginning users. @xref{Disabling}.
334 Short for `button down event' (q.v.@:).
337 A drag event is the kind of input event generated when you press a mouse
338 button, move the mouse, and then release the button. @xref{Mouse
342 A dribble file is a file into which Emacs writes all the characters that
343 the user types on the keyboard. Dribble files are used to make a record
344 for debugging Emacs bugs. Emacs does not make a dribble file unless you
345 tell it to. @xref{Bugs}.
348 The echo area is the bottom line of the screen, used for echoing the
349 arguments to commands, for asking questions, and printing brief messages
350 (including error messages). The messages are stored in the buffer
351 @samp{*Messages*} so you can review them later. @xref{Echo Area}.
354 Echoing is acknowledging the receipt of commands by displaying them (in
355 the echo area). Emacs never echoes single-character key sequences;
356 longer key sequences echo only if you pause while typing them.
359 We say that a character is electric if it is normally self-inserting
360 (q.v.@:), but the current major mode (q.v.@:) redefines it to do something
361 else as well. For example, some programming language major modes define
362 particular delimiter characters to reindent the line or insert one or
363 more newlines in addition to self-insertion.
366 End of line is a character or characters which signal an end of a text
367 line. On GNU and Unix systems, this is a newline (q.v.@:), but other
368 systems have other conventions. @xref{Coding Systems,end-of-line}.
369 Emacs can recognize several end-of-line conventions in files and convert
372 @item Environment Variable
373 An environment variable is one of a collection of variables stored by
374 the operating system, each one having a name and a value. Emacs can
375 access environment variables set by its parent shell, and it can set
376 variables in the environment it passes to programs it invokes.
383 An error occurs when an Emacs command cannot execute in the current
384 circumstances. When an error occurs, execution of the command stops
385 (unless the command has been programmed to do otherwise) and Emacs
386 reports the error by printing an error message (q.v.@:). Type-ahead
387 is discarded. Then Emacs is ready to read another editing command.
390 An error message is a single line of output displayed by Emacs when the
391 user asks for something impossible to do (such as, killing text
392 forward when point is at the end of the buffer). They appear in the
393 echo area, accompanied by a beep.
396 @key{ESC} is a character used as a prefix for typing Meta characters on
397 keyboards lacking a @key{META} key. Unlike the @key{META} key (which,
398 like the @key{SHIFT} key, is held down while another character is
399 typed), you press the @key{ESC} key as you would press a letter key, and
400 it applies to the next character you type.
403 Expunging an Rmail file or Dired buffer or a Gnus newsgroup buffer is an
404 operation that truly discards the messages or files you have previously
405 flagged for deletion.
408 A face is a style of displaying characters. It specifies attributes
409 such as font family and size, foreground and background colors,
410 underline and strike-through, background stipple, etc. Emacs provides
411 features to associate specific faces with portions of buffer text, in
412 order to display that text as specified by the face attributes.
415 Emacs uses file locking to notice when two different users
416 start to edit one file at the same time. @xref{Interlocking}.
419 A file name is a name that refers to a file. File names may be relative
420 or absolute; the meaning of a relative file name depends on the current
421 directory, but an absolute file name refers to the same file regardless
422 of which directory is current. On GNU and Unix systems, an absolute
423 file name starts with a slash (the root directory) or with @samp{~/} or
424 @samp{~@var{user}/} (a home directory). On MS-Windows/MS-DOS, and
425 absolute file name can also start with a drive letter and a colon
428 Some people use the term ``pathname'' for file names, but we do not;
429 we use the word ``path'' only in the term ``search path'' (q.v.@:).
431 @item File-Name Component
432 A file-name component names a file directly within a particular
433 directory. On GNU and Unix systems, a file name is a sequence of
434 file-name components, separated by slashes. For example, @file{foo/bar}
435 is a file name containing two components, @samp{foo} and @samp{bar}; it
436 refers to the file named @samp{bar} in the directory named @samp{foo} in
437 the current directory. MS-DOS/MS-Windows file names can also use
438 backslashes to separate components, as in @file{foo\bar}.
441 The fill prefix is a string that should be expected at the beginning
442 of each line when filling is done. It is not regarded as part of the
443 text to be filled. @xref{Filling}.
446 Filling text means shifting text between consecutive lines so that all
447 the lines are approximately the same length. @xref{Filling}. Some
448 other editors call this feature `line wrapping.'
451 Font Lock is a mode that highlights parts of buffer text according to
452 its syntax. @xref{Font Lock}.
455 A fontset is a named collection of fonts. A fontset specification lists
456 character sets and which font to use to display each of them. Fontsets
457 make it easy to change several fonts at once by specifying the name of a
458 fontset, rather than changing each font separately. @xref{Fontsets}.
461 Formatted text is text that displays with formatting information while
462 you edit. Formatting information includes fonts, colors, and specified
463 margins. @xref{Formatted Text}.
465 @item Formfeed Character
469 A frame is a rectangular cluster of Emacs windows. Emacs starts out
470 with one frame, but you can create more. You can subdivide each frame
471 into Emacs windows (q.v.@:). When you are using a windowing system, all
472 the frames can be visible at the same time. @xref{Frames}. Some
473 other editors use the term ``window'' for this, but in Emacs a window
474 means something else.
477 On windowed displays, there's a narrow portion of the frame (q.v.@:)
478 between the text area and the window's border. Emacs displays the
479 fringe using a special face (q.v.@:) called @code{fringe}.
483 FTP is an acronym for File Transfer Protocol. Emacs uses an FTP client
484 program to provide access to remote files (q.v.@:).
487 A function key is a key on the keyboard that sends input but does not
488 correspond to any character. @xref{Function Keys}.
491 Global means ``independent of the current environment; in effect
492 throughout Emacs.'' It is the opposite of local (q.v.@:). Particular
493 examples of the use of `global' appear below.
496 A global definition of an abbrev (q.v.@:) is effective in all major
497 modes that do not have local (q.v.@:) definitions for the same abbrev.
501 The global keymap (q.v.@:) contains key bindings that are in effect
502 except when overridden by local key bindings in a major mode's local
503 keymap (q.v.@:). @xref{Keymaps}.
505 @item Global Mark Ring
506 The global mark ring records the series of buffers you have recently
507 set a mark (q.v.@:) in. In many cases you can use this to backtrack
508 through buffers you have been editing in, or in which you have found
509 tags (see `tags table'). @xref{Global Mark Ring}.
511 @item Global Substitution
512 Global substitution means replacing each occurrence of one string by
513 another string through a large amount of text. @xref{Replace}.
515 @item Global Variable
516 The global value of a variable (q.v.@:) takes effect in all buffers
517 that do not have their own local (q.v.@:) values for the variable.
520 @item Graphic Character
521 Graphic characters are those assigned pictorial images rather than
522 just names. All the non-Meta (q.v.@:) characters except for the
523 Control (q.v.@:) characters are graphic characters. These include
524 letters, digits, punctuation, and spaces; they do not include
525 @key{RET} or @key{ESC}. In Emacs, typing a graphic character inserts
526 that character (in ordinary editing modes). @xref{Basic,,Basic Editing}.
529 Highlighting text means displaying it with a different foreground and/or
530 background color to make it stand out from the rest of the text in the
534 Hardcopy means printed output. Emacs has commands for making printed
535 listings of text in Emacs buffers. @xref{Hardcopy}.
538 @key{HELP} is the Emacs name for @kbd{C-h} or @key{F1}. You can type
539 @key{HELP} at any time to ask what options you have, or to ask what any
540 command does. @xref{Help}.
543 Help echo is a short message printed in the echo area when the mouse
544 pointer is located on portions of display that require some
545 explanations. Emacs displays help echo for menu items, parts of the
546 mode line, tool-bar buttons, etc. On graphics displays, the messages
547 can be displayed as tooltips (q.v.@:). @xref{Tooltips}.
550 A hook is a list of functions to be called on specific occasions, such
551 as saving a buffer in a file, major mode activation, etc. By
552 customizing the various hooks, you can modify Emacs's behavior without
553 changing any of its code. @xref{Hooks}.
556 Hyper is the name of a modifier bit which a keyboard input character may
557 have. To make a character Hyper, type it while holding down the
558 @key{HYPER} key. Such characters are given names that start with
559 @kbd{Hyper-} (usually written @kbd{H-} for short). @xref{User Input,
563 An inbox is a file in which mail is delivered by the operating system.
564 Rmail transfers mail from inboxes to Rmail files (q.v.@:) in which the
565 mail is then stored permanently or until explicitly deleted.
568 @item Incremental Search
569 Emacs provides an incremental search facility, whereby Emacs searches
570 for the string as you type it. @xref{Incremental Search}.
573 Indentation means blank space at the beginning of a line. Most
574 programming languages have conventions for using indentation to
575 illuminate the structure of the program, and Emacs has special
576 commands to adjust indentation.
579 @item Indirect Buffer
580 An indirect buffer is a buffer that shares the text of another buffer,
581 called its base buffer (q.v.@:). @xref{Indirect Buffers}.
584 Info is the hypertext format used by the GNU project for writing
588 An input event represents, within Emacs, one action taken by the user on
589 the terminal. Input events include typing characters, typing function
590 keys, pressing or releasing mouse buttons, and switching between Emacs
591 frames. @xref{User Input}.
594 An input method is a system for entering non-ASCII text characters by
595 typing sequences of ASCII characters (q.v.@:). @xref{Input Methods}.
598 Insertion means copying text into the buffer, either from the keyboard
599 or from some other place in Emacs.
602 Interlocking is a feature for warning when you start to alter a file
603 that someone else is already editing.
604 @xref{Interlocking,Interlocking,Simultaneous Editing}.
607 See `incremental search.'
610 Justification means adding extra spaces to lines of text to make them
611 come exactly to a specified width. @xref{Filling,Justification}.
614 Keyboard macros are a way of defining new Emacs commands from
615 sequences of existing ones, with no need to write a Lisp program.
616 @xref{Keyboard Macros}.
618 @cindex keyboard shortcuts
619 @item Keyboard Shortcut
620 A keyboard shortcut is a key sequence (q.v.@:) which invokes a
621 command. What other programs call ``assign a keyboard shortcut''
622 Emacs calls ``bind a key sequence''. See `binding.'
625 A key sequence (key, for short) is a sequence of input events (q.v.@:)
626 that are meaningful as a single unit. If the key sequence is enough to
627 specify one action, it is a complete key (q.v.@:); if it is not enough,
628 it is a prefix key (q.v.@:). @xref{Keys}.
631 The keymap is the data structure that records the bindings (q.v.@:) of
632 key sequences to the commands that they run. For example, the global
633 keymap binds the character @kbd{C-n} to the command function
634 @code{next-line}. @xref{Keymaps}.
636 @item Keyboard Translation Table
637 The keyboard translation table is an array that translates the character
638 codes that come from the terminal into the character codes that make up
639 key sequences. @xref{Keyboard Translations}.
642 The kill ring is where all text you have killed recently is saved.
643 You can reinsert any of the killed text still in the ring; this is
644 called yanking (q.v.@:). @xref{Yanking}.
647 Killing means erasing text and saving it on the kill ring so it can be
648 yanked (q.v.@:) later. Some other systems call this ``cutting.''
649 Most Emacs commands to erase text do killing, as opposed to deletion
650 (q.v.@:). @xref{Killing}.
653 Killing a job (such as, an invocation of Emacs) means making it cease
654 to exist. Any data within it, if not saved in a file, is lost.
657 @item Language Environment
658 Your choice of language environment specifies defaults for the input
659 method (q.v.@:) and coding system (q.v.@:). @xref{Language
660 Environments}. These defaults are relevant if you edit non-ASCII text
661 (@pxref{International}).
667 Lisp is a programming language. Most of Emacs is written in a dialect
668 of Lisp, called Emacs Lisp, that is extended with special features which
669 make it especially suitable for text editing tasks.
672 A list is, approximately, a text string beginning with an open
673 parenthesis and ending with the matching close parenthesis. In C mode
674 and other non-Lisp modes, groupings surrounded by other kinds of matched
675 delimiters appropriate to the language, such as braces, are also
676 considered lists. Emacs has special commands for many operations on
680 Local means ``in effect only in a particular context''; the relevant
681 kind of context is a particular function execution, a particular
682 buffer, or a particular major mode. It is the opposite of `global'
683 (q.v.@:). Specific uses of `local' in Emacs terminology appear below.
686 A local abbrev definition is effective only if a particular major mode
687 is selected. In that major mode, it overrides any global definition
688 for the same abbrev. @xref{Abbrevs}.
691 A local keymap is used in a particular major mode; the key bindings
692 (q.v.@:) in the current local keymap override global bindings of the
693 same key sequences. @xref{Keymaps}.
696 A local value of a variable (q.v.@:) applies to only one buffer.
700 @kbd{M-} in the name of a character is an abbreviation for @key{META},
701 one of the modifier keys that can accompany any character.
705 @kbd{M-C-} in the name of a character is an abbreviation for
706 Control-Meta; it means the same thing as @kbd{C-M-}. If your
707 terminal lacks a real @key{META} key, you type a Control-Meta character by
708 typing @key{ESC} and then typing the corresponding Control character.
709 @xref{User Input,C-M-}.
712 @kbd{M-x} is the key sequence which is used to call an Emacs command by
713 name. This is how you run commands that are not bound to key sequences.
714 @xref{M-x,M-x,Running Commands by Name}.
717 Mail means messages sent from one user to another through the computer
718 system, to be read at the recipient's convenience. Emacs has commands for
719 composing and sending mail, and for reading and editing the mail you have
720 received. @xref{Sending Mail}. @xref{Rmail}, for how to read mail.
722 @item Mail Composition Method
723 A mail composition method is a program runnable within Emacs for editing
724 and sending a mail message. Emacs lets you select from several
725 alternative mail composition methods. @xref{Mail Methods}.
728 The Emacs major modes are a mutually exclusive set of options, each of
729 which configures Emacs for editing a certain sort of text. Ideally,
730 each programming language has its own major mode. @xref{Major Modes}.
733 The mark points to a position in the text. It specifies one end of the
734 region (q.v.@:), point being the other end. Many commands operate on
735 all the text from point to the mark. Each buffer has its own mark.
739 The mark ring is used to hold several recent previous locations of the
740 mark, just in case you want to move back to them. Each buffer has its
741 own mark ring; in addition, there is a single global mark ring (q.v.@:).
745 The menu bar is the line at the top of an Emacs frame. It contains
746 words you can click on with the mouse to bring up menus, or you can use
747 a keyboard interface to navigate it. @xref{Menu Bars}.
753 Meta is the name of a modifier bit which a command character may have.
754 It is present in a character if the character is typed with the
755 @key{META} key held down. Such characters are given names that start
756 with @kbd{Meta-} (usually written @kbd{M-} for short). For example,
757 @kbd{M-<} is typed by holding down @key{META} and at the same time
758 typing @kbd{<} (which itself is done, on most terminals, by holding
759 down @key{SHIFT} and typing @kbd{,}). @xref{User Input,Meta}.
762 A Meta character is one whose character code includes the Meta bit.
765 The minibuffer is the window that appears when necessary inside the
766 echo area (q.v.@:), used for reading arguments to commands.
769 @item Minibuffer History
770 The minibuffer history records the text you have specified in the past
771 for minibuffer arguments, so you can conveniently use the same text
772 again. @xref{Minibuffer History}.
775 A minor mode is an optional feature of Emacs which can be switched on
776 or off independently of all other features. Each minor mode has a
777 command to turn it on or off. @xref{Minor Modes}.
779 @item Minor Mode Keymap
780 A minor mode keymap is a keymap that belongs to a minor mode and is
781 active when that mode is enabled. Minor mode keymaps take precedence
782 over the buffer's local keymap, just as the local keymap takes
783 precedence over the global keymap. @xref{Keymaps}.
786 The mode line is the line at the bottom of each window (q.v.@:), giving
787 status information on the buffer displayed in that window. @xref{Mode
790 @item Modified Buffer
791 A buffer (q.v.@:) is modified if its text has been changed since the
792 last time the buffer was saved (or since when it was created, if it
793 has never been saved). @xref{Saving}.
796 Moving text means erasing it from one place and inserting it in
797 another. The usual way to move text by killing (q.v.@:) and then
798 yanking (q.v.@:). @xref{Killing}.
801 MULE refers to the Emacs features for editing multilingual non-ASCII text
802 using multibyte characters (q.v.@:). @xref{International}.
804 @item Multibyte Character
805 A multibyte character is a character that takes up several bytes in a
806 buffer. Emacs uses multibyte characters to represent non-ASCII text,
807 since the number of non-ASCII characters is much more than 256.
808 @xref{International Chars, International Characters}.
811 A named mark is a register (q.v.@:) in its role of recording a
812 location in text so that you can move point to that location.
816 Narrowing means creating a restriction (q.v.@:) that limits editing in
817 the current buffer to only a part of the text in the buffer. Text
818 outside that part is inaccessible to the user until the boundaries are
819 widened again, but it is still there, and saving the file saves it
820 all. @xref{Narrowing}.
823 Control-J characters in the buffer terminate lines of text and are
824 therefore also called newlines. @xref{Text Characters,Newline}.
829 @code{nil} is a value usually interpreted as a logical ``false.'' Its
830 opposite is @code{t}, interpreted as ``true.''
832 @item Numeric Argument
833 A numeric argument is a number, specified before a command, to change
834 the effect of the command. Often the numeric argument serves as a
835 repeat count. @xref{Arguments}.
838 Overwrite mode is a minor mode. When it is enabled, ordinary text
839 characters replace the existing text after point rather than pushing
840 it to the right. @xref{Minor Modes}.
843 A page is a unit of text, delimited by formfeed characters (ASCII
844 control-L, code 014) coming at the beginning of a line. Some Emacs
845 commands are provided for moving over and operating on pages.
849 Paragraphs are the medium-size unit of human-language text. There are
850 special Emacs commands for moving over and operating on paragraphs.
854 We say that certain Emacs commands parse words or expressions in the
855 text being edited. Really, all they know how to do is find the other
856 end of a word or expression. @xref{Syntax}.
859 Point is the place in the buffer at which insertion and deletion
860 occur. Point is considered to be between two characters, not at one
861 character. The terminal's cursor (q.v.@:) indicates the location of
862 point. @xref{Basic,Point,Basic Editing}.
864 @item Prefix Argument
865 See `numeric argument.'
868 A prefix key is a key sequence (q.v.@:) whose sole function is to
869 introduce a set of longer key sequences. @kbd{C-x} is an example of
870 prefix key; any two-character sequence starting with @kbd{C-x} is
871 therefore a legitimate key sequence. @xref{Keys}.
873 @item Primary Rmail File
874 Your primary Rmail file is the file named @samp{RMAIL} in your home
875 directory. That's where Rmail stores your incoming mail, unless you
876 specify a different file name. @xref{Rmail}.
878 @item Primary Selection
879 The primary selection is one particular X selection (q.v.@:); it is the
880 selection that most X applications use for transferring text to and from
883 The Emacs kill commands set the primary selection and the yank command
884 uses the primary selection when appropriate. @xref{Killing}.
887 A prompt is text printed to ask the user for input. Displaying a prompt
888 is called prompting. Emacs prompts always appear in the echo area
889 (q.v.@:). One kind of prompting happens when the minibuffer is used to
890 read an argument (@pxref{Minibuffer}); the echoing which happens when
891 you pause in the middle of typing a multi-character key sequence is also
892 a kind of prompting (@pxref{Echo Area}).
895 Query-replace is an interactive string replacement feature provided by
896 Emacs. @xref{Query Replace}.
899 Quitting means canceling a partially typed command or a running
900 command, using @kbd{C-g} (or @kbd{C-@key{BREAK}} on MS-DOS). @xref{Quitting}.
903 Quoting means depriving a character of its usual special significance.
904 The most common kind of quoting in Emacs is with @kbd{C-q}. What
905 constitutes special significance depends on the context and on
906 convention. For example, an ``ordinary'' character as an Emacs command
907 inserts itself; so in this context, a special character is any character
908 that does not normally insert itself (such as @key{DEL}, for example),
909 and quoting it makes it insert itself as if it were not special. Not
910 all contexts allow quoting. @xref{Basic,Quoting,Basic Editing}.
912 @item Quoting File Names
913 Quoting a file name turns off the special significance of constructs
914 such as @samp{$}, @samp{~} and @samp{:}. @xref{Quoted File Names}.
916 @item Read-Only Buffer
917 A read-only buffer is one whose text you are not allowed to change.
918 Normally Emacs makes buffers read-only when they contain text which
919 has a special significance to Emacs; for example, Dired buffers.
920 Visiting a file that is write-protected also makes a read-only buffer.
924 A rectangle consists of the text in a given range of columns on a given
925 range of lines. Normally you specify a rectangle by putting point at
926 one corner and putting the mark at the opposite corner.
929 @item Recursive Editing Level
930 A recursive editing level is a state in which part of the execution of
931 a command involves asking the user to edit some text. This text may
932 or may not be the same as the text to which the command was applied.
933 The mode line indicates recursive editing levels with square brackets
934 (@samp{[} and @samp{]}). @xref{Recursive Edit}.
937 Redisplay is the process of correcting the image on the screen to
938 correspond to changes that have been made in the text being edited.
939 @xref{Screen,Redisplay}.
942 See `regular expression.'
945 The region is the text between point (q.v.@:) and the mark (q.v.@:).
946 Many commands operate on the text of the region. @xref{Mark,Region}.
949 Registers are named slots in which text or buffer positions or
950 rectangles can be saved for later use. @xref{Registers}. A related
951 Emacs feature is `bookmarks' (q.v.@:).
953 @item Regular Expression
954 A regular expression is a pattern that can match various text strings;
955 for example, @samp{a[0-9]+} matches @samp{a} followed by one or more
956 digits. @xref{Regexps}.
959 A remote file is a file that is stored on a system other than your own.
960 Emacs can access files on other computers provided that they are
961 connected to the same network as your machine. @xref{Remote Files}.
964 See `numeric argument.'
967 See `global substitution.'
970 A buffer's restriction is the amount of text, at the beginning or the
971 end of the buffer, that is temporarily inaccessible. Giving a buffer a
972 nonzero amount of restriction is called narrowing (q.v.@:); removing
973 a restriction is called widening (q.v.@:). @xref{Narrowing}.
976 @key{RET} is a character that in Emacs runs the command to insert a
977 newline into the text. It is also used to terminate most arguments
978 read in the minibuffer (q.v.@:). @xref{User Input,Return}.
981 Reverting means returning to the original state. Emacs lets you
982 revert a buffer by re-reading its file from disk. @xref{Reverting}.
985 An Rmail file is a file containing text in a special format used by
986 Rmail for storing mail. @xref{Rmail}.
989 Saving a buffer means copying its text into the file that was visited
990 (q.v.@:) in that buffer. This is the way text in files actually gets
991 changed by your Emacs editing. @xref{Saving}.
994 A scroll bar is a tall thin hollow box that appears at the side of a
995 window. You can use mouse commands in the scroll bar to scroll the
996 window. The scroll bar feature is supported only under windowing
997 systems. @xref{Scroll Bars}.
1000 Scrolling means shifting the text in the Emacs window so as to see a
1001 different part of the buffer. @xref{Display,Scrolling}.
1004 Searching means moving point to the next occurrence of a specified
1005 string or the next match for a specified regular expression.
1009 A search path is a list of directory names, to be used for searching for
1010 files for certain purposes. For example, the variable @code{load-path}
1011 holds a search path for finding Lisp library files. @xref{Lisp Libraries}.
1013 @item Secondary Selection
1014 The secondary selection is one particular X selection; some X
1015 applications can use it for transferring text to and from other
1016 applications. Emacs has special mouse commands for transferring text
1017 using the secondary selection. @xref{Secondary Selection}.
1020 Selecting a buffer means making it the current (q.v.@:) buffer.
1021 @xref{Buffers,Selecting}.
1024 Windowing systems allow an application program to specify
1025 selections whose values are text. A program can also read the
1026 selections that other programs have set up. This is the principal way
1027 of transferring text between window applications. Emacs has commands to
1028 work with the primary (q.v.@:) selection and the secondary (q.v.@:)
1029 selection, and also with the clipboard (q.v.@:).
1031 @item Self-Documentation
1032 Self-documentation is the feature of Emacs which can tell you what any
1033 command does, or give you a list of all commands related to a topic
1034 you specify. You ask for self-documentation with the help character,
1035 @kbd{C-h}. @xref{Help}.
1037 @item Self-Inserting Character
1038 A character is self-inserting if typing that character inserts that
1039 character in the buffer. Ordinary printing and whitespace characters
1040 are self-inserting in Emacs, except in certain special major modes.
1043 Emacs has commands for moving by or killing by sentences.
1047 A sexp (short for ``s-expression'') is the basic syntactic unit of Lisp
1048 in its textual form: either a list, or Lisp atom. Many Emacs commands
1049 operate on sexps. The term `sexp' is generalized to languages other
1050 than Lisp, to mean a syntactically recognizable expression, such as a
1051 block or a parenthesized expression in C. @xref{Lists,Sexps}.
1053 @item Simultaneous Editing
1054 Simultaneous editing means two users modifying the same file at once.
1055 Simultaneous editing if not detected can cause one user to lose his
1056 work. Emacs detects all cases of simultaneous editing and warns one
1057 of the users to investigate.
1058 @xref{Interlocking,Interlocking,Simultaneous Editing}.
1061 Speedbar is a special tall frame that provides fast access to Emacs
1062 buffers, functions within those buffers, Info nodes, and other
1063 interesting parts of text within Emacs. @xref{Speedbar}.
1065 @item Spell Checking
1066 Spell checking means checking correctness of the written form of each
1067 one of the words in a text. Emacs uses the Ispell spelling-checker
1068 program to check the spelling of parts of a buffer via a convenient user
1069 interface. @xref{Spelling}.
1072 A string is a kind of Lisp data object which contains a sequence of
1073 characters. Many Emacs variables are intended to have strings as
1074 values. The Lisp syntax for a string consists of the characters in the
1075 string with a @samp{"} before and another @samp{"} after. A @samp{"}
1076 that is part of the string must be written as @samp{\"} and a @samp{\}
1077 that is part of the string must be written as @samp{\\}. All other
1078 characters, including newline, can be included just by writing them
1079 inside the string; however, backslash sequences as in C, such as
1080 @samp{\n} for newline or @samp{\241} using an octal character code, are
1083 @item String Substitution
1084 See `global substitution'.
1086 @item Syntax Highlighting
1090 The syntax table tells Emacs which characters are part of a word,
1091 which characters balance each other like parentheses, etc.
1095 Super is the name of a modifier bit which a keyboard input character may
1096 have. To make a character Super, type it while holding down the
1097 @key{SUPER} key. Such characters are given names that start with
1098 @kbd{Super-} (usually written @kbd{s-} for short). @xref{User Input,
1102 Suspending Emacs means stopping it temporarily and returning control
1103 to its parent process, which is usually a shell. Unlike killing a job
1104 (q.v.@:), you can later resume the suspended Emacs job without losing
1105 your buffers, unsaved edits, undo history, etc. @xref{Exiting}.
1108 A tags table is a file that serves as an index to the function
1109 definitions in one or more other files. @xref{Tags}.
1111 @item Termscript File
1112 A termscript file contains a record of all characters sent by Emacs to
1113 the terminal. It is used for tracking down bugs in Emacs redisplay.
1114 Emacs does not make a termscript file unless you tell it to.
1118 Two meanings (@pxref{Text}):
1122 Data consisting of a sequence of characters, as opposed to binary
1123 numbers, executable programs, and the like. The basic contents of an
1124 Emacs buffer (aside from the text properties, q.v.@:) are always text
1127 Data consisting of written human language, as opposed to programs,
1128 or following the stylistic conventions of human language.
1131 @item Text-only Terminal
1132 A text-only terminal is a display that is limited to displaying text in
1133 character units. Such a terminal cannot control individual pixels it
1134 displays. Emacs supports a subset of display features on text-only
1137 @item Text Properties
1138 Text properties are annotations recorded for particular characters in
1139 the buffer. Images in the buffer are recorded as text properties;
1140 they also specify formatting information. @xref{Editing Format Info}.
1143 The tool bar is a line (sometimes multiple lines) of icons at the top
1144 of an Emacs frame. Clicking on one of these icons executes a command.
1145 You can think of this as a graphical relative of the menu bar (q.v.@:).
1149 Tooltips are small windows displaying a help echo (q.v.@:) text that
1150 explains parts of the display, lists useful options available via mouse
1151 clicks, etc. @xref{Tooltips}.
1154 Top level is the normal state of Emacs, in which you are editing the
1155 text of the file you have visited. You are at top level whenever you
1156 are not in a recursive editing level (q.v.@:) or the minibuffer
1157 (q.v.@:), and not in the middle of a command. You can get back to top
1158 level by aborting (q.v.@:) and quitting (q.v.@:). @xref{Quitting}.
1161 Transposing two units of text means putting each one into the place
1162 formerly occupied by the other. There are Emacs commands to transpose
1163 two adjacent characters, words, sexps (q.v.@:) or lines
1164 (@pxref{Transpose}).
1167 Truncating text lines in the display means leaving out any text on a
1168 line that does not fit within the right margin of the window
1169 displaying it. See also `continuation line.'
1170 @xref{Basic,Truncation,Basic Editing}.
1173 See `text-only terminal.'
1176 Undoing means making your previous editing go in reverse, bringing
1177 back the text that existed earlier in the editing session.
1181 A user option is a variable (q.v.@:) that exists so that you can customize
1182 Emacs by setting it to a new value. @xref{Variables}.
1185 A variable is an object in Lisp that can store an arbitrary value.
1186 Emacs uses some variables for internal purposes, and has others (known
1187 as `user options' (q.v.@:)) just so that you can set their values to
1188 control the behavior of Emacs. The variables used in Emacs that you
1189 are likely to be interested in are listed in the Variables Index in
1190 this manual (@pxref{Variable Index}). @xref{Variables}, for
1191 information on variables.
1193 @item Version Control
1194 Version control systems keep track of multiple versions of a source file.
1195 They provide a more powerful alternative to keeping backup files (q.v.@:).
1196 @xref{Version Control}.
1199 Visiting a file means loading its contents into a buffer (q.v.@:)
1200 where they can be edited. @xref{Visiting}.
1203 Whitespace is any run of consecutive formatting characters (space,
1204 tab, newline, and backspace).
1207 Widening is removing any restriction (q.v.@:) on the current buffer;
1208 it is the opposite of narrowing (q.v.@:). @xref{Narrowing}.
1211 Emacs divides a frame (q.v.@:) into one or more windows, each of which
1212 can display the contents of one buffer (q.v.@:) at any time.
1213 @xref{Screen}, for basic information on how Emacs uses the screen.
1214 @xref{Windows}, for commands to control the use of windows. Some
1215 other editors use the term ``window'' for what we call a `frame'
1222 Word search is searching for a sequence of words, considering the
1223 punctuation between them as insignificant. @xref{Word Search}.
1226 WYSIWYG stands for ``What you see is what you get.'' Emacs generally
1227 provides WYSIWYG editing for files of characters; in Enriched mode
1228 (@pxref{Formatted Text}), it provides WYSIWYG editing for files that
1229 include text formatting information.
1232 Yanking means reinserting text previously killed. It can be used to
1233 undo a mistaken kill, or for copying or moving text. Some other
1234 systems call this ``pasting.'' @xref{Yanking}.