Metamodel user guide
Specifies the occurrence of signal sending and receiving or operation calls.
An execution occurence specification is a kind of message end. It specifies the occurrence of message events, such as sending and receiving signals or invoking or receiving operation calls. Messages are generated either by synchronous operation calls or asynchronous signal sends. They are received by the execution of corresponding accept event actions. It can also represent an execution occurrence specification : in other words, it can represent a moment in time at which actions or behaviors start or finish.
Figure 151 : ExecutionOccurenceSpecification (1)