A more human-readable table of the keycode constants listed in "Prototype.js’s Event class":http://www.prototypejs.org/api/event:

|*Name*|*Keycode*|*Use*|
|Backspace / Back delete|KEY_BACKSPACE|Event.KEY_BACKSPACE|
|Tab|KEY_TAB|Event.KEY_TAB|
|Return / Enter|KEY_RETURN|Event.KEY_RETURN|
|Escape / Esc|KEY_ESC|Event.KEY_ESC|
|Arrow left|KEY_LEFT|Event.KEY_LEFT|
|Arrow up|KEY_UP|Event.KEY_UP|
|Arrow right|KEY_RIGHT|Event.KEY_RIGHT|
|Arrow down|KEY_DOWN|Event.KEY_DOWN|
|Delete / Forward delete / Del|KEY_DELETE|Event.KEY_DELETE|
|Home|KEY_HOME|Event.KEY_HOME|
|Page up|KEY_PAGEUP|Event.KEY_PAGEUP|
|Page down|KEY_PAGEDOWN|Event.KEY_PAGEDOWN|