You notice the Ticket object changes state as it moves through this activity diagram. When the Ticket Agent performs the Generate Pass activity, the Ticket object has the valid state. After the Boarding Agent performs the Stamp Pass activity the Ticket changes to the used state.

 Tip   Use a connector when you run out of space in an activity diagram. For example, we ran out of room at the Receive Pass activity that the passenger performs. So, we placed a connector with the label A. Then we drew a control-flow line from Receive Pass to the A connector. Using the same technique, you can pick up the control-flow path at the connector with the same label A at the top of the Passenger’s swim lane, and then proceed to the Wait in line activity.