In sequence diagrams, an execution occurrence is created
automatically when you create a synchronous or an asynchronous message.
You can create an execution occurrence manually to show the start
and finish behavior in an interaction. You can also nest execution
occurrences to indicate nested behavior in a call sequence.
To create an execution occurrence:
- Open a sequence diagram that contains at least
one lifeline with messages.
- In the Palette, click Execution Occurrence.
- In the interaction frame, click the target lifeline at
a position that does not have an existing execution occurrence. If the target lifeline has an existing execution occurrence,
you create a nested execution occurrence that appears with a horizontal
offset that covers part of the original execution occurrence.
Note: If you want to delete an execution
occurrence, it cannot have a return message.