Only embedded and independent subprocesses are used in BPMN diagrams. Occurrence copies are used instead of the referenced subprocesses. The type is defined by the Subprocess type attribute (BPMN > Subprocess attribute group). If this attribute has not been specified, it is assumed that it is an embedded subprocess.
Embedded subprocesses
Embedded subprocesses are modeled as part of the subprocess object. The connection between the subprocess components and the subprocess object is represented by the belongs to connection.
Independent subprocesses
Independent subprocesses are modeled separately and assigned to the subprocess object.
Representation types
There are two types of representation for the subprocess object of these subprocess types:
In the Subprocess (collapsed) status, the details of the subprocess are represented in a separate model, which is assigned to the subprocess object. Double-clicking + results in an embedded subprocess to be represented as part of the subprocess function in the current model and opens an independent subprocess in a separate model.
Not BPMN 1.x
An event subprocess is instantiated when its start event is triggered by the associated throw event. The start event can have the Interrupting and Non-interrupting properties. If the start event is Non-interrupting, the surrounding activity is executed in parallel to the event subprocess. If the start event is Interrupting, the surrounding process or subprocess is canceled when the start event is triggered.