Interactions and Activities
The behavioral aspects of Interactions and Activities are modeled using the Behavior tab of the element Properties dialog, which enables you to assign parameters and return types to the elements.
Use the Edit Parameters button to edit an element's parameters. When you create a new parameter using the dialog, it internally creates an Activity Parameter Node for an Activity or an Interaction Parameter for an Interaction. In the Return field, click on the drop-down arrow and select the return type of the element.
The specification field is populated automatically when an operation is associated with the activity as a behavior.