anchor.diff:  
   
   A call activity is visualized the same as a <<bpmnSubProcessGraphicalNotation,subprocess>>, however with a thick border (collapsed and expanded). Depending on the modeling tool, a call activity can also be expanded, but the default visualization is the collapsed subprocess representation.
  -          
  +
   image::images/bpmn.collapsed.call.activity.png[align="center"]
   
   
  
positive.code: ----
  <startEvent id="theStart" />
  <sequenceFlow id="flow1" sourceRef="theStart" targetRef="fork" />
      
  <parallelGateway id="fork" />
  <sequenceFlow sourceRef="fork" targetRef="receivePayment" />
  <sequenceFlow sourceRef="fork" targetRef="shipOrder" />
      
  <userTask id="receivePayment" name="Receive Payment" />  
  <sequenceFlow sourceRef="receivePayment" targetRef="join" />
      
  <userTask id="shipOrder" name="Ship Order" /> 
  <sequenceFlow sourceRef="shipOrder" targetRef="join" />
      
  <parallelGateway id="join" />
  <sequenceFlow sourceRef="join" targetRef="archiveOrder" />
      
  <userTask id="archiveOrder" name="Archive Order" /> 
  <sequenceFlow sourceRef="archiveOrder" targetRef="theEnd" />
      
  <endEvent id="theEnd" />
  ----
  
  
negative.code: [source,xml,linenums]
  ----
  <process >
  
    ...
  
    <userTask id='theTask' name='important task' >
      <potentialOwner>
        <resourceAssignmentExpression>
  