Parameter names are not properties, and are not defined by a property rule:

• If the parameter is an output (result) of the activity, your activity can set values for it using the Property-Set method with the Param keyword followed by the parameter name. (The parameter page is available to the calling activity only when the Pass current parameter page? checkbox is selected in the Call instruction.)

• Recording an activity's outputs or results on the parameter page is only useful when the parameter page is passed into this activity by reference, using the Pass current parameter page? checkbox in the Call instruction. When checked, one parameter page is shared between the calling and called activity. Otherwise, parameters on the called activity's parameter page are not available to the calling activity after a return.

  
  

  The Call instruction in an activity examines the In/Out value of each parameter in the called activity:

  
  

  If the parameter is declared as Out and the entire parameter page of the current activity is shared with the calling activity, then the value of the Out parameter in the call may be of the form param.name. If the called activity updates the output parameter, the resulting value is available on the parameter page of the calling activity.

  
  

  If a parameter is declared as Outand the value of the parameter in the Call panel is itself a property reference, then traditional call-by-reference semantics applies. That is, if the called activity updates the parameter value, the value of the property itself is updated.

  
  

  Accordingly, do not list a local variable as the destination for an Out parameter. Do not pass a parameter reference as the destination for an Out parameter, unless passing the entire parameter page.

  
  

   

  
  

  In a chain of calling activities (activity Alpha calls Beta which calls Gamma), a property passed by reference from Alpha to Beta can also be passed by reference to Gamma, and changes to the Out parameter made within Gamma can be passed all the way back to Alpha. This corresponds to the behavior of call-by-reference in many programming languages.