State model interactions
A state machine may generate a signal to itself or to some other state machine. Only those signals sent outward, to some other state machine, are shown on the class collaboration diagram. This sort of interaction is considered the default case and doesn't involve any special arrow notation. So if you see any message name without any kind of arrow associated with it, you can assume it is a signal directed at a state machine.
To verify that this is really the case, you should be able to see each of the above signals appearing as events handled by the destination state machine table. Any event triggering a transition (as opposed to a can't happen or ignore response) will also appear on that state machine's diagram as well, as is the case in the example above.
You should also see these two signals generated by the source state machine somewhere inside one or more activities (actions within each state).
If you want to dive deeper into the platform independent timing and synchronization of dispatched events in Executable UML, please see this video.
An asterisk preceding a signal name indicates a creation event. This type of signal will cause an instance of its destination to be created first before the event is delivered.
If you look at the destination you will see an initial transition labeled with that event name.
