elisp: Controlling Active Maps
21.9 Controlling the Active Keymaps
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-- Variable: global-map
This variable contains the default global keymap that maps Emacs
keyboard input to commands. The global keymap is normally this
keymap. The default global keymap is a full keymap that binds
‘self-insert-command’ to all of the printing characters.
It is normal practice to change the bindings in the global keymap,
but you should not assign this variable any value other than the
keymap it starts out with.
-- Function: current-global-map
This function returns the current global keymap. This is the same
as the value of ‘global-map’ unless you change one or the other.
The return value is a reference, not a copy; if you use
‘define-key’ or other functions on it you will alter global
bindings.
(current-global-map)
⇒ (keymap [set-mark-command beginning-of-line ...
delete-backward-char])
-- Function: current-local-map
This function returns the current buffer’s local keymap, or ‘nil’
if it has none. In the following example, the keymap for the
‘*scratch*’ buffer (using Lisp Interaction mode) is a sparse keymap
in which the entry for <ESC>, ASCII code 27, is another sparse
keymap.
(current-local-map)
⇒ (keymap
(10 . eval-print-last-sexp)
(9 . lisp-indent-line)
(127 . backward-delete-char-untabify)
(27 keymap
(24 . eval-defun)
(17 . indent-sexp)))
‘current-local-map’ returns a reference to the local keymap, not a
copy of it; if you use ‘define-key’ or other functions on it you will
alter local bindings.
-- Function: current-minor-mode-maps
This function returns a list of the keymaps of currently enabled
minor modes.
-- Function: use-global-map keymap
This function makes KEYMAP the new current global keymap. It
returns ‘nil’.
It is very unusual to change the global keymap.
-- Function: use-local-map keymap
This function makes KEYMAP the new local keymap of the current
buffer. If KEYMAP is ‘nil’, then the buffer has no local keymap.
‘use-local-map’ returns ‘nil’. Most major mode commands use this
function.
-- Variable: minor-mode-map-alist
This variable is an alist describing keymaps that may or may not be
active according to the values of certain variables. Its elements
look like this:
(VARIABLE . KEYMAP)
The keymap KEYMAP is active whenever VARIABLE has a non-‘nil’
value. Typically VARIABLE is the variable that enables or disables
a minor mode. 
Keymaps and Minor Modes.
Note that elements of ‘minor-mode-map-alist’ do not have the same
structure as elements of ‘minor-mode-alist’. The map must be the
CDR of the element; a list with the map as the second element will
not do. The CDR can be either a keymap (a list) or a symbol whose
function definition is a keymap.
When more than one minor mode keymap is active, the earlier one in
‘minor-mode-map-alist’ takes priority. But you should design minor
modes so that they don’t interfere with each other. If you do this
properly, the order will not matter.
See Keymaps and Minor Modes, for more information about
minor modes. See also ‘minor-mode-key-binding’ (Functions
for Key Lookup).
-- Variable: minor-mode-overriding-map-alist
This variable allows major modes to override the key bindings for
particular minor modes. The elements of this alist look like the
elements of ‘minor-mode-map-alist’: ‘(VARIABLE . KEYMAP)’.
If a variable appears as an element of
‘minor-mode-overriding-map-alist’, the map specified by that
element totally replaces any map specified for the same variable in
‘minor-mode-map-alist’.
‘minor-mode-overriding-map-alist’ is automatically buffer-local in
all buffers.
-- Variable: overriding-local-map
If non-‘nil’, this variable holds a keymap to use instead of the
buffer’s local keymap, any text property or overlay keymaps, and
any minor mode keymaps. This keymap, if specified, overrides all
other maps that would have been active, except for the current
global map.
-- Variable: overriding-terminal-local-map
If non-‘nil’, this variable holds a keymap to use instead of
‘overriding-local-map’, the buffer’s local keymap, text property or
overlay keymaps, and all the minor mode keymaps.
This variable is always local to the current terminal and cannot be
buffer-local. Multiple Terminals. It is used to implement
incremental search mode.
-- Variable: overriding-local-map-menu-flag
If this variable is non-‘nil’, the value of ‘overriding-local-map’
or ‘overriding-terminal-local-map’ can affect the display of the
menu bar. The default value is ‘nil’, so those map variables have
no effect on the menu bar.
Note that these two map variables do affect the execution of key
sequences entered using the menu bar, even if they do not affect
the menu bar display. So if a menu bar key sequence comes in, you
should clear the variables before looking up and executing that key
sequence. Modes that use the variables would typically do this
anyway; normally they respond to events that they do not handle by
“unreading” them and exiting.
-- Variable: special-event-map
This variable holds a keymap for special events. If an event type
has a binding in this keymap, then it is special, and the binding
for the event is run directly by ‘read-event’. Special
Events.
-- Variable: emulation-mode-map-alists
This variable holds a list of keymap alists to use for emulation
modes. It is intended for modes or packages using multiple
minor-mode keymaps. Each element is a keymap alist which has the
same format and meaning as ‘minor-mode-map-alist’, or a symbol with
a variable binding which is such an alist. The active keymaps in
each alist are used before ‘minor-mode-map-alist’ and
‘minor-mode-overriding-map-alist’.
-- Function: set-transient-map keymap &optional keep-pred on-exit
This function adds KEYMAP as a “transient” keymap, which takes
precedence over other keymaps for one (or more) subsequent keys.
Normally, KEYMAP is used just once, to look up the very next key.
If the optional argument KEEP-PRED is ‘t’, the map stays active as
long as the user types keys defined in KEYMAP; when the user types
a key that is not in KEYMAP, the transient keymap is deactivated
and normal key lookup continues for that key.
The KEEP-PRED argument can also be a function. In that case, the
function is called with no arguments, prior to running each
command, while KEYMAP is active; it should return non-‘nil’ if
KEYMAP should stay active.
The optional argument ON-EXIT, if non-nil, specifies a function
that is called, with no arguments, after KEYMAP is deactivated.
This function works by adding and removing KEYMAP from the variable
‘overriding-terminal-local-map’, which takes precedence over all
other active keymaps (Searching Keymaps).
Info Catalog
elisp: Searching Keymaps
elisp: Keymaps
elisp: Key Lookup