4.3.4 How long does the system wait for a response?

The system waits for responses for a pre-defined specific amount of time.

The system waits for responses for a pre-defined specific amount of time (this happens at states 3, 5, and 8. We have indicated such ``time windows'' in the diagram by writing [Listening...]). If there is no answer within the time limit at a state with a ``time window'', the system carries out a specified default action. We indicate default actions by marking the corresponding edge label with a little asterisk .

So for instance at state 3 the system waits for user input for some time. If, however, there is no input within that time, the system goes to state 7 because that is the default action. From there it moves to state 8 and asks for a floor specification again. If there is no response in due time after that second prompt in a row, the elevator asks the user to use the keyboard and it is reset to the starting point.