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(elisp)Function Keys

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Function Keys
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   Most keyboards also have "function keys"--keys that have names or
symbols that are not characters.  Function keys are represented in Emacs
Lisp as symbols; the symbol's name is the function key's label, in lower
case.  For example, pressing a key labeled <F1> places the symbol `f1'
in the input stream.

   The event type of a function key event is the event symbol itself.
Note: Classifying Events.

   Here are a few special cases in the symbol-naming convention for
function keys:

`backspace', `tab', `newline', `return', `delete'
     These keys correspond to common ASCII control characters that have
     special keys on most keyboards.

     In ASCII, `C-i' and <TAB> are the same character.  If the terminal
     can distinguish between them, Emacs conveys the distinction to
     Lisp programs by representing the former as the integer 9, and the
     latter as the symbol `tab'.

     Most of the time, it's not useful to distinguish the two.  So
     normally `function-key-map' (Note: Translating Input) is set up
     to map `tab' into 9.  Thus, a key binding for character code 9 (the
     character `C-i') also applies to `tab'.  Likewise for the other
     symbols in this group.  The function `read-char' likewise converts
     these events into characters.

     In ASCII, <BS> is really `C-h'.  But `backspace' converts into the
     character code 127 (<DEL>), not into code 8 (<BS>).  This is what
     most users prefer.

`left', `up', `right', `down'
     Cursor arrow keys

`kp-add', `kp-decimal', `kp-divide', ...
     Keypad keys (to the right of the regular keyboard).

`kp-0', `kp-1', ...
     Keypad keys with digits.

`kp-f1', `kp-f2', `kp-f3', `kp-f4'
     Keypad PF keys.

`kp-home', `kp-left', `kp-up', `kp-right', `kp-down'
     Keypad arrow keys.  Emacs normally translates these into the
     corresponding non-keypad keys `home', `left', ...

`kp-prior', `kp-next', `kp-end', `kp-begin', `kp-insert', `kp-delete'
     Additional keypad duplicates of keys ordinarily found elsewhere.
     Emacs normally translates these into the like-named non-keypad
     keys.

   You can use the modifier keys <ALT>, <CTRL>, <HYPER>, <META>,
<SHIFT>, and <SUPER> with function keys.  The way to represent them is
with prefixes in the symbol name:

`A-'
     The alt modifier.

`C-'
     The control modifier.

`H-'
     The hyper modifier.

`M-'
     The meta modifier.

`S-'
     The shift modifier.

`s-'
     The super modifier.

   Thus, the symbol for the key <F3> with <META> held down is `M-f3'.
When you use more than one prefix, we recommend you write them in
alphabetical order; but the order does not matter in arguments to the
key-binding lookup and modification functions.