An Activity MAY be a target for Sequence Flows; it can have multiple incoming Sequence Flows. Incoming Sequence Flows MAY be from an alternative path and/or parallel paths. If the Activity does not have an incoming Sequence Flow, then the Activity MUST be instantiated when the Process is instantiated.
An Activity MAY be a source for Sequence Flows; it can have multiple outgoing Sequence Flows. If there are multiple outgoing Sequence Flows, then this means that a separate parallel path is being created for each Sequence Flow (i.e., tokens will be generated for each outgoing Sequence Flow from the Activity). If the Activity does not have an outgoing Sequence Flow, then the Activity marks the end of one or more paths in the Process. When the Activity ends and there are no other parallel paths active, then the Process MUST be completed.