have special keys you can type them with: for example, @key{RET},
@key{TAB}, @key{DEL} and @key{ESC}. The space character is usually
referred to below as @key{SPC}, even though strictly speaking it is a
-graphic character whose graphic happens to be blank. Some keyboards
-have a key labeled ``linefeed'' which is an alias for @kbd{C-j}.
+graphic character whose graphic happens to be blank.
Emacs extends the @acronym{ASCII} character set with thousands more printing
characters (@pxref{International}), additional control characters, and a
But the Emacs character set has room for control variants of all
printing characters, and for distinguishing between @kbd{C-a} and
-@kbd{C-A}. The X Window System makes it possible to enter all these
-characters. For example, @kbd{C--} (that's Control-Minus) and @kbd{C-5}
-are meaningful Emacs commands under X.
+@kbd{C-A}. Graphical terminals make it possible to enter all these
+characters. For example, @kbd{C--} (that's Control-Minus) and
+@kbd{C-5} are meaningful Emacs commands on a graphical terminal.
Another Emacs character-set extension is additional modifier bits.
Only one modifier bit is commonly used; it is called Meta. Every
character has a Meta variant; examples include @kbd{Meta-a} (normally
-written @kbd{M-a}, for short), @kbd{M-A} (not the same character as
-@kbd{M-a}, but those two characters normally have the same meaning in
-Emacs), @kbd{M-@key{RET}}, and @kbd{M-C-a}. For reasons of tradition,
-we usually write @kbd{C-M-a} rather than @kbd{M-C-a}; logically
-speaking, the order in which the modifier keys @key{CTRL} and @key{META}
-are mentioned does not matter.
+written @kbd{M-a}, for short), @kbd{M-A} (different from @kbd{M-a},
+but they are normally equivalent in Emacs), @kbd{M-@key{RET}}, and
+@kbd{M-C-a}. That last means @kbd{a} with both the @key{CTRL} and
+@key{META} modifiers. We usually write it as @kbd{C-M-a} rather than
+@kbd{M-C-a}, for reasons of tradition.
@cindex Meta
@cindex M-
@cindex @key{ESC} replacing @key{META} key
Some terminals have a @key{META} key, and allow you to type Meta
-characters by holding this key down. Thus, @kbd{Meta-a} is typed by
-holding down @key{META} and pressing @kbd{a}. The @key{META} key
-works much like the @key{SHIFT} key. Such a key is not always labeled
-@key{META}, however, as this function is often a special option for a
-key with some other primary purpose. Sometimes it is labeled
-@key{ALT} or @key{EDIT}; on a Sun keyboard, it may have a diamond on
-it.
+characters by holding this key down. Thus, you can type @kbd{Meta-a}
+by holding down @key{META} and pressing @kbd{a}. The @key{META} key
+works much like the @key{SHIFT} key. In fact, this key is more often
+labeled @key{ALT} or @key{EDIT}, instead of @key{META}; on a Sun
+keyboard, it may have a diamond on it.
If there is no @key{META} key, you can still type Meta characters
using two-character sequences starting with @key{ESC}. Thus, you can
@key{ESC} is allowed on terminals with @key{META} keys, too, in case
you have formed a habit of using it.
- The X Window System provides several other modifier keys that can be
-applied to any input character. These are called @key{SUPER},
-@key{HYPER} and @key{ALT}. We write @samp{s-}, @samp{H-} and @samp{A-}
-to say that a character uses these modifiers. Thus, @kbd{s-H-C-x} is
-short for @kbd{Super-Hyper-Control-x}. Not all X terminals actually
+ Emacs defines several other modifier keys that can be applied to any
+input character. These are called @key{SUPER}, @key{HYPER} and
+@key{ALT}. We write @samp{s-}, @samp{H-} and @samp{A-} to say that a
+character uses these modifiers. Thus, @kbd{s-H-C-x} is short for
+@kbd{Super-Hyper-Control-x}. Not all graphical terminals actually
provide keys for these modifier flags---in fact, many terminals have a
key labeled @key{ALT} which is really a @key{META} key. The standard
key bindings of Emacs do not include any characters with these
-modifiers. But you can assign them meanings of your own by customizing
-Emacs.
+modifiers. But you can assign them meanings of your own by
+customizing Emacs.
If your keyboard lacks one of these modifier keys, you can enter it
using @kbd{C-x @@}: @kbd{C-x @@ h} adds the ``hyper'' flag to the next
two modifiers by using @kbd{C-x @@} twice for the same character,
because the first one goes to work on the @kbd{C-x}.)
- Keyboard input includes keyboard keys that are not characters at all:
-for example function keys and arrow keys. Mouse buttons are also
-outside the gamut of characters. You can modify these events with the
-modifier keys @key{CTRL}, @key{META}, @key{SUPER}, @key{HYPER} and
-@key{ALT}, just like keyboard characters.
+ Keyboard input includes keyboard keys that are not characters at
+all: for example function keys and arrow keys. Mouse buttons are also
+outside the gamut of characters. However, you can modify these events
+with the modifier keys @key{CTRL}, @key{META}, @key{SUPER},
+@key{HYPER} and @key{ALT}, just as you can modify keyboard characters.
@cindex input event
Input characters and non-character inputs are collectively called
@dfn{input events}. @xref{Input Events,,, elisp, The Emacs Lisp
-Reference Manual}, for more information. If you are not doing Lisp
-programming, but simply want to redefine the meaning of some characters
-or non-character events, see @ref{Customization}.
+Reference Manual}, for the full Lisp-level details. If you are not
+doing Lisp programming, but simply want to redefine the meaning of
+some characters or non-character events, see @ref{Customization}.
@acronym{ASCII} terminals cannot really send anything to the computer except
@acronym{ASCII} characters. These terminals use a sequence of characters to
All told, the prefix keys in Emacs are @kbd{C-c}, @kbd{C-h},
@kbd{C-x}, @kbd{C-x @key{RET}}, @kbd{C-x @@}, @kbd{C-x a}, @kbd{C-x
-n}, @w{@kbd{C-x r}}, @kbd{C-x v}, @kbd{C-x 4}, @kbd{C-x 5}, @kbd{C-x 6},
-@key{ESC}, @kbd{M-o} and @kbd{M-g}. (@key{F1} and @key{F2} are aliases for
-@kbd{C-h} and @kbd{C-x 6}.) But this list is not cast in concrete; it
-is just a matter of Emacs's standard key bindings. If you customize
-Emacs, you can make new prefix keys, or eliminate these. @xref{Key
-Bindings}.
+n}, @w{@kbd{C-x r}}, @kbd{C-x v}, @kbd{C-x 4}, @kbd{C-x 5}, @kbd{C-x
+6}, @key{ESC}, @kbd{M-g}, and @kbd{M-o}. (@key{F1} and @key{F2} are
+aliases for @kbd{C-h} and @kbd{C-x 6}.) But this list is not cast in
+concrete; it is just a matter of Emacs's standard key bindings. If
+you customize Emacs, you can make new prefix keys, or eliminate some
+of the standard ones. @xref{Key Bindings}.
If you do make or eliminate prefix keys, that changes the set of
possible key sequences. For example, if you redefine @kbd{C-f} as a
definition of @kbd{C-x 4}, then @kbd{C-x 4 f} (or @kbd{C-x 4
@var{anything}}) is no longer a key.
- Typing the help character (@kbd{C-h} or @key{F1}) after a prefix
-key displays a list of the commands starting with that prefix.
-There are a few prefix keys for which @kbd{C-h} does not
-work---for historical reasons, they have other meanings for @kbd{C-h}
-which are not easy to change. But @key{F1} should work for all prefix
-keys.
+ Typing the help character (@kbd{C-h} or @key{F1}) after a prefix key
+displays a list of the commands starting with that prefix. There are
+a few prefix keys for which @kbd{C-h} does not work---for historical
+reasons, they define other meanings for @kbd{C-h} which are painful to
+change. But @key{F1} should work for all prefix keys.
@node Commands, Text Characters, Keys, Top
@section Keys and Commands
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