The flow activity is used to specify one or more activities to be performed concurrently. You can define explicit control dependencies between nested child activities using a <<link>> stereotype within a flow activity.
Syntax:
<flow standard-attributes>
standard-elements
<links>?
<link name="NCName" />+
</links>
activity+
</flow>
Mapping
You design a flow activity using a synchronization object.
You can also design a flow activity using a composite process with a <<Flow>> stereotype, when the flow activity has specific properties.