Ignore

Ignoring an event

That optional destination in the grammar — (SP '>' SP state_name)? — is not an accident. An event name on its own, with no > and no destination, means the event is accepted in this state and deliberately ignored:

Consider the door's OPENING state:

transitions
    Door opened > OPEN
    Passenger close > CLOSING
    Passenger open
    Lock

Those last two events are ignored. It makes sense since if the door is already in the process of opening any open button presses by a passenger would simply be ignored in the real world.

Notice then that ignore event reponses are proper system behavior, not errors!