Turning an Activity into a sub process
To change an activity into a sub process, double click the activity shape and select the sub process slider.
An activity can be changed into a sub process by double clicking the activity and from the properties editor, select the sub process slider.
When an activity is changed to a sub process, it appears differently on the diagram. The activity shape has a green plus (+) shown in the top left.
The sub process
Changing an activity into a sub process allows the activity to be broken down into more detail with a series of sub process activity steps. To edit the sub process definition, click the green plus (+) in the top left of the activity shape. This will display a new diagram in which the details of the sub process can be captured.
The example above shows that the CAB Review activity has been decomposed into a sub process. The sub process will have a start and stop (as do all process definitions) and proceeds through 3 sub activities Schedule CAB Meeting, Invite Attendees and Hold Meeting. You can make the sub process definition as simple or complex as you like. The activities at this level can also be changed into sub processes and you would then define a third level of decomposition.
To return to the parent process (in this case where CAB Review is defined), click the Up button in the top left of the diagram.