I am currently using jBPM 4.4, I see in the document have been supported and supportBPMN2.0 subprocess 【Reusable (call activity)】, the problem is I can not referencean external process to a certain process, has reached the general Purpose?

Ex

<process id="boundary_signal_event" name="Signal Boundary Event Process">

  <startEvent id="startEvent" name="StartProcess"/>

   <sequenceFlow id="flow1" sourceRef="startEvent" targetRef="subProcess"/>

    <subProcess id="subProcess" name="Hello" >

     ...

    </subProcess>

I only wrote "..." subprocess in the details of it? Or under the subprocess's Id ("subProcess") or name ("Hello") can refer to an already Deployment of Process?