The event keyUp occurs when a key is released that is not designated to be a function key.
Information about the key in question can be obtained using the macro %%EvKey.
Hint: It is more likely that a key requires "action logic" when the key is released then when it is depressed.
In the context of this event, the macro %%EvKey returns a string describing the meaning of the key (e.g. "F8", "ENTER", "ALT", "ESC").
In MWAPI, this event is called "KEYUP". Go to the alphabetic list of events.