Aminet 1 (Walnut Creek)/Aminet - June 1993 [Walnut Creek].iso/aminet/util/gnu/emacs_src_18_58.lha/emacs-18.58/info/emacs-13

GNU Info File | 1992-02-21 | 32KB | 638 lines

This is Info file ../info/emacs, produced by Makeinfo-1.43 from the
input file emacs.tex.
   This file documents the GNU Emacs editor.
   Copyright (C) 1985, 1986, 1988 Richard M. Stallman.
   Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.
   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the sections entitled "The GNU Manifesto", "Distribution" and "GNU
General Public License" are included exactly as in the original, and
provided that the entire resulting derived work is distributed under
the terms of a permission notice identical to this one.
   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the sections entitled "The GNU Manifesto",
"Distribution" and "GNU General Public License" may be included in a
translation approved by the author instead of in the original English.
File: emacs,  Node: Glossary,  Next: Key Index,  Prev: Intro,  Up: Top
Glossary
********
Abbrev
     An abbrev is a text string which expands into a different text
     string when present in the buffer.  For example, you might define
     a short word as an abbrev for a long phrase that you want to
     insert frequently.  *Note Abbrevs::.
Aborting
     Aborting means getting out of a recursive edit (q.v.).  The
     commands `C-]' and `M-x top-level' are used for this.  *Note
     Quitting::.
Auto Fill mode
     Auto Fill mode is a minor mode in which text that you insert is
     automatically broken into lines of fixed width.  *Note Filling::.
Auto Saving
     Auto saving is when Emacs automatically stores the contents of an
     Emacs buffer in a specially-named file so that the information
     will not be lost if the buffer is lost due to a system error or
     user error.  *Note Auto Save::.
Backup File
     A backup file records the contents that a file had before the
     current editing session.  Emacs makes backup files automatically
     to help you track down or cancel changes you later regret making.
      *Note Backup::.
Balance Parentheses
     Emacs can balance parentheses manually or automatically.  Manual
     balancing is done by the commands to move over balanced
     expressions (*note Lists::.).  Automatic balancing is done by
     blinking the parenthesis that matches one just inserted (*note
     Matching Parens: Matching.).
     To bind a key is to change its binding (q.v.).  *Note Rebinding::.
Binding
     A key gets its meaning in Emacs by having a binding which is a
     command (q.v.), a Lisp function that is run when the key is typed.
     *Note Binding: Commands.  Customization often involves rebinding a
     character to a different command function.  The bindings of all
     keys are recorded in the keymaps (q.v.).  *Note Keymaps::.
Blank Lines
     Blank lines are lines that contain only whitespace.  Emacs has
     several commands for operating on the blank lines in the buffer.
Buffer
     The buffer is the basic editing unit; one buffer corresponds to
     one piece of text being edited.  You can have several buffers,
     but at any time you are editing only one, the `selected' buffer,
     though several can be visible when you are using multiple
     windows.  *Note Buffers::.
Buffer Selection History
     Emacs keeps a buffer selection history which records how recently
     each Emacs buffer has been selected.  This is used for choosing a
     buffer to select.  *Note Buffers::.
     `C' in the name of a character is an abbreviation for Control.
     *Note C-: Characters.
     `C-M-' in the name of a character is an abbreviation for
     Control-Meta.  *Note C-M-: Characters.
Case Conversion
     Case conversion means changing text from upper case to lower case
     or vice versa.  *Note Case::, for the commands for case
     conversion.
Characters
     Characters form the contents of an Emacs buffer; also, Emacs
     commands are invoked by keys (q.v.), which are sequences of one
     or more characters.  *Note Characters::.
Command
     A command is a Lisp function specially defined to be able to
     serve as a key binding in Emacs.  When you type a key (q.v.), its
     binding (q.v.) is looked up in the relevant keymaps (q.v.) to
     find the command to run.  *Note Commands::.
Command Name
     A command name is the name of a Lisp symbol which is a command
     (*note Commands::.).  You can invoke any command by its name using
     `M-x' (*note M-x::.).
Comments
     A comment is text in a program which is intended only for humans
     reading the program, and is marked specially so that it will be
     ignored when the program is loaded or compiled.  Emacs offers
     special commands for creating, aligning and killing comments.
     *Note Comments::.
Compilation
     Compilation is the process of creating an executable program from
     source code.  Emacs has commands for compiling files of Emacs Lisp
     code (*note Lisp Libraries::.) and programs in C and other
     languages (*note Compilation::.).
Complete Key
     A complete key is a character or sequence of characters which,
     when typed by the user, fully specifies one action to be
     performed by Emacs.  For example, `X' and `Control-f' and
     `Control-x m' are keys.  Keys derive their meanings from being
     bound (q.v.) to commands (q.v.).  Thus, `X' is conventionally
     bound to a command to insert `X' in the buffer; `C-x m' is
     conventionally bound to a command to begin composing a mail
     message. *Note Keys::.
Completion
     Completion is what Emacs does when it automatically fills out an
     abbreviation for a name into the entire name.  Completion is done
     for minibuffer (q.v.) arguments when the set of possible valid
     inputs is known; for example, on command names, buffer names, and
     file names.  Completion occurs when TAB, SPC or RET is typed.
     *Note Completion::.
Continuation Line
     When a line of text is longer than the width of the screen, it
     takes up more than one screen line when displayed.  We say that
     the text line is continued, and all screen lines used for it
     after the first are called continuation lines.  *Note
     Continuation: Basic.
Control-Character
     ASCII characters with octal codes 0 through 037, and also code
     0177, do not have graphic images assigned to them.  These are the
     control characters.  Any control character can be typed by
     holding down the CTRL key and typing some other character; some
     have special keys on the keyboard.  RET, TAB, ESC, LFD and DEL
     are all control characters.  *Note Characters::.
Copyleft
     A copyleft is a notice giving the public legal permission to
     redistribute a program or other work of art.  Copylefts are used
     by leftists to enrich the public just as copyrights are used by
     rightists to gain power over the public.
Current Buffer
     The current buffer in Emacs is the Emacs buffer on which most
     editing commands operate.  You can select any Emacs buffer as the
     current one.  *Note Buffers::.
Current Line
     The line point is on (*note Point::.).
Current Paragraph
     The paragraph that point is in.  If point is between paragraphs,
     the current paragraph is the one that follows point.  *Note
     Paragraphs::.
Current Defun
     The defun (q.v.) that point is in.  If point is between defuns,
     the current defun is the one that follows point.  *Note Defuns::.
Cursor
     The cursor is the rectangle on the screen which indicates the
     position called point (q.v.) at which insertion and deletion
     takes place.  The cursor is on or under the character that
     follows point.  Often people speak of `the cursor' when, strictly
     speaking, they mean `point'.  *Note Cursor: Basic.
Customization
     Customization is making minor changes in the way Emacs works.  It
     is often done by setting variables (*note Variables::.) or by
     rebinding keys (*note Keymaps::.).
Default Argument
     The default for an argument is the value that will be assumed if
     you do not specify one.  When the minibuffer is used to read an
     argument, the default argument is used if you just type RET.
     *Note Minibuffer::.
Default Directory
     When you specify a file name that does not start with `/' or `~',
     it is interpreted relative to the current buffer's default
     directory.  *Note Default Directory: Minibuffer File.
Defun
     A defun is a list at the top level of parenthesis or bracket
     structure in a program.  It is so named because most such lists
     in Lisp programs are calls to the Lisp function `defun'.  *Note
     Defuns::.
     DEL is a character that runs the command to delete one character
     of text.  *Note DEL: Basic.
Deletion
     Deletion means erasing text without saving it.  Emacs deletes text
     only when it is expected not to be worth saving (all whitespace,
     or only one character).  The alternative is killing (q.v.).
     *Note Deletion: Killing.
Deletion of Files
     Deleting a file means erasing it from the file system.  *Note
     Misc File Ops::.
Deletion of Messages
     Deleting a message means flagging it to be eliminated from your
     mail file.  This can be undone by undeletion until the mail file
     is expunged.  *Note Rmail Deletion::.
Deletion of Windows
     Deleting a window means eliminating it from the screen.  Other
     windows expand to use up the space.  The deleted window can never
     come back, but no actual text is thereby lost.  *Note Windows::.
Directory
     Files in the Unix file system are grouped into file directories.
     *Note Directories: ListDir.
Dired
     Dired is the Emacs facility that displays the contents of a file
     directory and allows you to "edit the directory", performing
     operations on the files in the directory.  *Note Dired::.
Disabled Command
     A disabled command is one that you may not run without special
     confirmation.  The usual reason for disabling a command is that
     it is confusing for beginning users.  *Note Disabling::.
Dribble File
     A file into which Emacs writes all the characters that the user
     types on the keyboard.  Dribble files are used to make a record
     for debugging Emacs bugs.  Emacs does not make a dribble file
     unless you tell it to.  *Note Bugs::.
Echo Area
     The echo area is the bottom line of the screen, used for echoing
     the arguments to commands, for asking questions, and printing
     brief messages (including error messages).  *Note Echo Area::.
Echoing
     Echoing is acknowledging the receipt of commands by displaying
     them (in the echo area).  Emacs never echoes single-character
     keys; longer keys echo only if you pause while typing them.
Error
     An error occurs when an Emacs command cannot execute in the
     current circumstances.  When an error occurs, execution of the
     command stops (unless the command has been programmed to do
     otherwise) and Emacs reports the error by printing an error
     message (q.v.).  Type-ahead is discarded.  Then Emacs is ready to
     read another editing command.
Error Messages
     Error messages are single lines of output printed by Emacs when
     the user asks for something impossible to do (such as, killing
     text forward when point is at the end of the buffer).  They
     appear in the echo area, accompanied by a beep.
     ESC is a character, used to end incremental searches and as a
     prefix for typing Meta characters on keyboards lacking a META
     key.  Unlike the META key (which, like the SHIFT key, is held
     down while another character is typed), the ESC key is pressed
     once and applies to the next character typed.
Fill Prefix
     The fill prefix is a string that should be expected at the
     beginning of each line when filling is done.  It is not regarded
     as part of the text to be filled.  *Note Filling::.
Filling
     Filling text means moving text from line to line so that all the
     lines are approximately the same length.  *Note Filling::.
Global
     Global means `independent of the current environment; in effect
     throughout Emacs'.  It is the opposite of local (q.v.).
     Particular examples of the use of `global' appear below.
Global Abbrev
     A global definition of an abbrev (q.v.) is effective in all major
     modes that do not have local (q.v.) definitions for the same
     abbrev.  *Note Abbrevs::.
Global Keymap
     The global keymap (q.v.) contains key bindings that are in effect
     except when overridden by local key bindings in a major mode's
     local keymap (q.v.).  *Note Keymaps::.
Global Substitution
     Global substitution means replacing each occurrence of one string
     by another string through a large amount of text.  *Note
     Replace::.
Global Variable
     The global value of a variable (q.v.) takes effect in all buffers
     that do not have their own local (q.v.) values for the variable.
     *Note Variables::.
Graphic Character
     Graphic characters are those assigned pictorial images rather than
     just names.  All the non-Meta (q.v.) characters except for the
     Control (q.v.) characters are graphic characters.  These include
     letters, digits, punctuation, and spaces; they do not include RET
     or ESC.  In Emacs, typing a graphic character inserts that
     character (in ordinary editing modes).  *Note Basic Editing:
     Basic.
Grinding
     Grinding means adjusting the indentation in a program to fit the
     nesting structure.  *Note Grinding: Indentation.
Hardcopy
     Hardcopy means printed output.  Emacs has commands for making
     printed listings of text in Emacs buffers.  *Note Hardcopy::.
     You can type HELP at any time to ask what options you have, or to
     ask what any command does.  HELP is really `Control-h'.  *Note
     Help::.
Inbox
     An inbox is a file in which mail is delivered by the operating
     system.  Rmail transfers mail from inboxes to mail files (q.v.)
     in which the mail is then stored permanently or until explicitly
     deleted.  *Note Rmail Inbox::.
Indentation
     Indentation means blank space at the beginning of a line.  Most
     programming languages have conventions for using indentation to
     illuminate the structure of the program, and Emacs has special
     features to help you set up the correct indentation.  *Note
     Indentation::.
Insertion
     Insertion means copying text into the buffer, either from the
     keyboard or from some other place in Emacs.
Justification
     Justification means adding extra spaces to lines of text to make
     them come exactly to a specified width.  *Note Justification:
     Filling.
Keyboard Macros
     Keyboard macros are a way of defining new Emacs commands from
     sequences of existing ones, with no need to write a Lisp program.
     *Note Keyboard Macros::.
     A key is a sequence of characters that, when input to Emacs,
     specify or begin to specify a single action for Emacs to perform.
      That is, the sequence is not more than a single unit.  If the
     key is enough to specify one action, it is a complete key (q.v.);
     if it is less than enough, it is a prefix key (q.v.).  *Note
     Keys::.
Keymap
     The keymap is the data structure that records the bindings (q.v.)
     of keys to the commands that they run.  For example, the keymap
     binds the character `C-n' to the command function `next-line'.
     *Note Keymaps::.
Kill Ring
     The kill ring is where all text you have killed recently is saved.
     You can reinsert any of the killed text still in the ring; this is
     called yanking (q.v.).  *Note Yanking::.
Killing
     Killing means erasing text and saving it on the kill ring so it
     can be yanked (q.v.) later.  Some other systems call this
     "cutting".  Most Emacs commands to erase text do killing, as
     opposed to deletion (q.v.).  *Note Killing::.
Killing Jobs
     Killing a job (such as, an invocation of Emacs) means making it
     cease to exist.  Any data within it, if not saved in a file, is
     lost.  *Note Exiting::.
     A list is, approximately, a text string beginning with an open
     parenthesis and ending with the matching close parenthesis.  In C
     mode and other non-Lisp modes, groupings surrounded by other
     kinds of matched delimiters appropriate to the language, such as
     braces, are also considered lists.  Emacs has special commands
     for many operations on lists.  *Note Lists::.
Local
     Local means `in effect only in a particular context'; the relevant
     kind of context is a particular function execution, a particular
     buffer, or a particular major mode.  It is the opposite of
     `global' (q.v.).  Specific uses of `local' in Emacs terminology
     appear below.
Local Abbrev
     A local abbrev definition is effective only if a particular major
     mode is selected.  In that major mode, it overrides any global
     definition for the same abbrev.  *Note Abbrevs::.
Local Keymap
     A local keymap is used in a particular major mode; the key
     bindings (q.v.) in the current local keymap override global
     bindings of the same keys.  *Note Keymaps::.
Local Variable
     A local value of a variable (q.v.) applies to only one buffer.
     *Note Locals::.
     `M-' in the name of a character is an abbreviation for META, one
     of the modifier keys that can accompany any character.  *Note
     Characters::.
     `M-C-' in the name of a character is an abbreviation for
     Control-Meta; it means the same thing as `C-M-'.  If your
     terminal lacks a real META key, you type a Control-Meta character
     by typing ESC and then typing the corresponding Control character.
     *Note C-M-: Characters.
     `M-x' is the key which is used to call an Emacs command by name.
     This is how commands that are not bound to keys are called.
     *Note M-x::.
     Mail means messages sent from one user to another through the
     computer system, to be read at the recipient's convenience.
     Emacs has commands for composing and sending mail, and for
     reading and editing the mail you have received.  *Note Sending
     Mail::.  *Note Rmail::, for how to read mail.
Mail File
     A mail file is a file which is edited using Rmail and in which
     Rmail stores mail.  *Note Rmail::.
Major Mode
     The major modes are a mutually exclusive set of options each of
     which configures Emacs for editing a certain sort of text.
     Ideally, each programming language has its own major mode.  *Note
     Major Modes::.
     The mark points to a position in the text.  It specifies one end
     of the region (q.v.), point being the other end.  Many commands
     operate on all the text from point to the mark.  *Note Mark::.
Mark Ring
     The mark ring is used to hold several recent previous locations
     of the mark, just in case you want to move back to them.  *Note
     Mark Ring::.
Message
     See `mail'.
     Meta is the name of a modifier bit which a command character may
     have.  It is present in a character if the character is typed
     with the META key held down.  Such characters are given names
     that start with `Meta-'.  For example, `Meta-<' is typed by
     holding down META and at the same time typing `<' (which itself
     is done, on most terminals, by holding down SHIFT and typing `,').
     *Note Meta: Characters.
Meta Character
     A Meta character is one whose character code includes the Meta
     bit.
Minibuffer
     The minibuffer is the window that appears when necessary inside
     the echo area (q.v.), used for reading arguments to commands.
     *Note Minibuffer::.
Minor Mode
     A minor mode is an optional feature of Emacs which can be
     switched on or off independently of all other features.  Each
     minor mode has a command to turn it on or off.  *Note Minor
     Modes::.
Mode Line
     The mode line is the line at the bottom of each text window
     (q.v.), which gives status information on the buffer displayed in
     that window.  *Note Mode Line::.
Modified Buffer
     A buffer (q.v.) is modified if its text has been changed since the
     last time the buffer was saved (or since when it was created, if
     it has never been saved).  *Note Saving::.
Moving Text
     Moving text means erasing it from one place and inserting it in
     another.  This is done by killing (q.v.) and then yanking (q.v.).
     *Note Killing::.
Named Mark
     A named mark is a register (q.v.) in its role of recording a
     location in text so that you can move point to that location.
     *Note Registers::.
Narrowing
     Narrowing means creating a restriction (q.v.) that limits editing
     in the current buffer to only a part of the text in the buffer.
     Text outside that part is inaccessible to the user until the
     boundaries are widened again, but it is still there, and saving
     the file saves it all.  *Note Narrowing::.
Newline
     LFD characters in the buffer terminate lines of text and are
     called newlines.  *Note Newline: Characters.
Numeric Argument
     A numeric argument is a number, specified before a command, to
     change the effect of the command.  Often the numeric argument
     serves as a repeat count.  *Note Arguments::.
Option
     An option is a variable (q.v.) that exists so that you can
     customize Emacs by giving it a new value.  *Note Variables::.
Overwrite Mode
     Overwrite mode is a minor mode.  When it is enabled, ordinary text
     characters replace the existing text after point rather than
     pushing it to the right.  *Note Minor Modes::.
     A page is a unit of text, delimited by formfeed characters (ASCII
     Control-L, code 014) coming at the beginning of a line.  Some
     Emacs commands are provided for moving over and operating on
     pages.  *Note Pages::.
Paragraphs
     Paragraphs are the medium-size unit of English text.  There are
     special Emacs commands for moving over and operating on
     paragraphs.  *Note Paragraphs::.
Parsing
     We say that Emacs parses words or expressions in the text being
     edited.  Really, all it knows how to do is find the other end of a
     word or expression.  *Note Syntax::.
Point
     Point is the place in the buffer at which insertion and deletion
     occur.  Point is considered to be between two characters, not at
     one character.  The terminal's cursor (q.v.) indicates the
     location of point.  *Note Point: Basic.
Prefix Key
     A prefix key is a key (q.v.) whose sole function is to introduce a
     set of multi-character keys.  `Control-x' is an example of prefix
     key; thus, any two-character sequence starting with `C-x' is also
     a legitimate key.  *Note Keys::.
Primary Mail File
     Your primary mail file is the file named `RMAIL' in your home
     directory, where all mail that you receive is stored by Rmail
     unless you make arrangements to do otherwise.  *Note Rmail::.
Prompt
     A prompt is text printed to ask the user for input.  Printing a
     prompt is called prompting.  Emacs prompts always appear in the
     echo area (q.v.).  One kind of prompting happens when the
     minibuffer is used to read an argument (*note Minibuffer::.); the
     echoing which happens when you pause in the middle of typing a
     multicharacter key is also a kind of prompting (*note Echo
     Area::.).
Quitting
     Quitting means cancelling a partially typed command or a running
     command, using `C-g'.  *Note Quitting::.
Quoting
     Quoting means depriving a character of its usual special
     significance.  In Emacs this is usually done with `Control-q'.
     What constitutes special significance depends on the context and
     on convention.  For example, an "ordinary" character as an Emacs
     command inserts itself; so in this context, a special character
     is any character that does not normally insert itself (such as
     DEL, for example), and quoting it makes it insert itself as if it
     were not special.  Not all contexts allow quoting.  *Note
     Quoting: Basic.
Read-only Buffer
     A read-only buffer is one whose text you are not allowed to
     change.  Normally Emacs makes buffers read-only when they contain
     text which has a special significance to Emacs; for example,
     Dired buffers.  Visiting a file that is write protected also
     makes a read-only buffer.  *Note Buffers::.
Recursive Editing Level
     A recursive editing level is a state in which part of the
     execution of a command involves asking the user to edit some
     text.  This text may or may not be the same as the text to which
     the command was applied.  The mode line indicates recursive
     editing levels with square brackets (`[' and `]').  *Note
     Recursive Edit::.
Redisplay
     Redisplay is the process of correcting the image on the screen to
     correspond to changes that have been made in the text being
     edited.  *Note Redisplay: Screen.
Regexp
     See `regular expression'.
Region
     The region is the text between point (q.v.) and the mark (q.v.).
     Many commands operate on the text of the region.  *Note Region:
     Mark.
Registers
     Registers are named slots in which text or buffer positions or
     rectangles can be saved for later use.  *Note Registers::.
Regular Expression
     A regular expression is a pattern that can match various text
     strings; for example, `l[0-9]+' matches `l' followed by one or
     more digits.  *Note Regexps::.
Replacement
     See `global substitution'.
Restriction
     A buffer's restriction is the amount of text, at the beginning or
     the end of the buffer, that is temporarily invisible and
     inaccessible.  Giving a buffer a nonzero amount of restriction is
     called narrowing (q.v.).  *Note Narrowing::.
     RET is a character than in Emacs runs the command to insert a
     newline into the text.  It is also used to terminate most
     arguments read in the minibuffer (q.v.).  *Note Return:
     Characters.
Saving
     Saving a buffer means copying its text into the file that was
     visited (q.v.) in that buffer.  This is the way text in files
     actually gets changed by your Emacs editing.  *Note Saving::.
Scrolling
     Scrolling means shifting the text in the Emacs window so as to
     see a different part of the buffer.  *Note Scrolling: Display.
Searching
     Searching means moving point to the next occurrence of a specified
     string.  *Note Search::.
Selecting
     Selecting a buffer means making it the current (q.v.) buffer.
     *Note Selecting: Buffers.
Self-documentation
     Self-documentation is the feature of Emacs which can tell you
     what any command does, or give you a list of all commands related
     to a topic you specify.  You ask for self-documentation with the
     help character, `C-h'.  *Note Help::.
Sentences
     Emacs has commands for moving by or killing by sentences.  *Note
     Sentences::.
     A sexp (short for `s-expression') is the basic syntactic unit of
     Lisp in its textual form: either a list, or Lisp atom.  Many
     Emacs commands operate on sexps.  The term `sexp' is generalized
     to languages other than Lisp, to mean a syntactically
     recognizable expression.  *Note Sexps: Lists.
Simultaneous Editing
     Simultaneous editing means two users modifying the same file at
     once.  Simultaneous editing if not detected can cause one user to
     lose his work.  Emacs detects all cases of simultaneous editing
     and warns the user to investigate them.  *Note Simultaneous
     Editing: Interlocking.
String
     A string is a kind of Lisp data object which contains a sequence
     of characters.  Many Emacs variables are intended to have strings
     as values.  The Lisp syntax for a string consists of the
     characters in the string with a `"' before and another `"' after.
      A `"' that is part of the string must be written as `\"' and a
     `\' that is part of the string must be written as `\\'.  All
     other characters, including newline, can be included just by
     writing them inside the string; however, escape sequences as in
     C, such as `\n' for newline or `\241' using an octal character
     code, are allowed as well.
String Substitution
     See `global substitution'.
Syntax Table
     The syntax table tells Emacs which characters are part of a word,
     which characters balance each other like parentheses, etc.  *Note
     Syntax::.
Tag Table
     A tag table is a file that serves as an index to the function
     definitions in one or more other files.  *Note Tags::.
Termscript File
     A termscript file contains a record of all characters sent by
     Emacs to the terminal.  It is used for tracking down bugs in
     Emacs redisplay.  Emacs does not make a termscript file unless
     you tell it to.  *Note Bugs::.
     Two meanings (*note Text::.):
        * Data consisting of a sequence of characters, as opposed to
          binary numbers, images, graphics commands, executable
          programs, and the like.  The contents of an Emacs buffer are
          always text in this sense.
        * Data consisting of written human language, as opposed to
          programs, or following the stylistic conventions of human
          language.
Top Level
     Top level is the normal state of Emacs, in which you are editing
     the text of the file you have visited.  You are at top level
     whenever you are not in a recursive editing level (q.v.) or the
     minibuffer (q.v.), and not in the middle of a command.  You can
     get back to top level by aborting (q.v.) and quitting (q.v.).
     *Note Quitting::.
Transposition
     Transposing two units of text means putting each one into the
     place formerly occupied by the other.  There are Emacs commands
     to transpose two adjacent characters, words, sexps (q.v.) or lines
     (*note Transpose::.).
Truncation
     Truncating text lines in the display means leaving out any text
     on a line that does not fit within the right margin of the window
     displaying it.  See also `continuation line'.  *Note Truncation:
     Basic.
Undoing
     Undoing means making your previous editing go in reverse, bringing
     back the text that existed earlier in the editing session.  *Note
     Undo::.
Variable
     A variable is an object in Lisp that can store an arbitrary value.
     Emacs uses some variables for internal purposes, and has others
     (known as `options' (q.v.)) just so that you can set their values
     to control the behavior of Emacs.  The variables used in Emacs
     that you are likely to be interested in are listed in the
     Variables Index in this manual.  *Note Variables::, for
     information on variables.
Visiting
     Visiting a file means loading its contents into a buffer (q.v.)
     where they can be edited.  *Note Visiting::.
Whitespace
     Whitespace is any run of consecutive formatting characters (space,
     tab, newline, and backspace).
Widening
     Widening is removing any restriction (q.v.) on the current buffer;
     it is the opposite of narrowing (q.v.).  *Note Narrowing::.
Window
     Emacs divides the screen into one or more windows, each of which
     can display the contents of one buffer (q.v.) at any time.  *Note
     Screen::, for basic information on how Emacs uses the screen.
     *Note Windows::, for commands to control the use of windows.
Word Abbrev
     Synonymous with `abbrev'.
Word Search
     Word search is searching for a sequence of words, considering the
     punctuation between them as insignificant.  *Note Word Search::.
Yanking
     Yanking means reinserting text previously killed.  It can be used
     to undo a mistaken kill, or for copying or moving text.  Some
     other systems call this "pasting".  *Note Yanking::.