Info Catalog elisp: Input Events elisp: Function Keys

elisp: Keyboard Events

 
 20.7.1 Keyboard Events
 ----------------------
 
 There are two kinds of input you can get from the keyboard: ordinary
 keys, and function keys.  Ordinary keys correspond to characters; the
 events they generate are represented in Lisp as characters.  The event
 type of a character event is the character itself (an integer); see
 Classifying Events.
 
    An input character event consists of a “basic code” between 0 and
 524287, plus any or all of these “modifier bits”:
 
 meta
      The 2**27 bit in the character code indicates a character typed
      with the meta key held down.
 
 control
      The 2**26 bit in the character code indicates a non-ASCII control
      character.
 
      ASCII control characters such as ‘C-a’ have special basic codes of
      their own, so Emacs needs no special bit to indicate them.  Thus,
      the code for ‘C-a’ is just 1.
 
      But if you type a control combination not in ASCII, such as ‘%’
      with the control key, the numeric value you get is the code for ‘%’
      plus 2**26 (assuming the terminal supports non-ASCII control
      characters).
 
 shift
      The 2**25 bit in the character code indicates an ASCII control
      character typed with the shift key held down.
 
      For letters, the basic code itself indicates upper versus lower
      case; for digits and punctuation, the shift key selects an entirely
      different character with a different basic code.  In order to keep
      within the ASCII character set whenever possible, Emacs avoids
      using the 2**25 bit for those characters.
 
      However, ASCII provides no way to distinguish ‘C-A’ from ‘C-a’, so
      Emacs uses the 2**25 bit in ‘C-A’ and not in ‘C-a’.
 
 hyper
      The 2**24 bit in the character code indicates a character typed
      with the hyper key held down.
 
 super
      The 2**23 bit in the character code indicates a character typed
      with the super key held down.
 
 alt
      The 2**22 bit in the character code indicates a character typed
      with the alt key held down.  (The key labeled <Alt> on most
      keyboards is actually treated as the meta key, not this.)
 
    It is best to avoid mentioning specific bit numbers in your program.
 To test the modifier bits of a character, use the function
 ‘event-modifiers’ (Classifying Events).  When making key
 bindings, you can use the read syntax for characters with modifier bits
 (‘\C-’, ‘\M-’, and so on).  For making key bindings with ‘define-key’,
 you can use lists such as ‘(control hyper ?x)’ to specify the characters
 (Changing Key Bindings).  The function ‘event-convert-list’
 converts such a list into an event type (Classifying Events).
 

Info Catalog elisp: Input Events elisp: Function Keys