12.3. Open Questions

1 Are the succession multiplicities in an example flawed?

The following example (from SysML 7.13.5) defines a part type Camera with the two action steps focus and shoot, and with three successions: the first one named multiFocusing and the two others without a name:

part def Camera {
  action focus[*] : Focus;
  action shoot[*] : Shoot;
  // A focus action may be preceded by a previous focus action.
  succession multiFocusing
    first [0..1] focus then [0..1] focus;
  // A shoot must be preceded by a focus.
  first [1] focus then [0..1] shoot;
  // A focus action may be preceded by a shoot action.
  first [0..1] shoot then [1] focus;
}

None of the specified succession multiplicities makes sense for a Camera part definition.

2 Why do SysML2 control nodes not specialize the corresponding KerML control nodes?

KerML defines control nodes as steps that are typed by control behaviors, which are predefined in the ControlPerformances library.

SysML2 defines control nodes, such as DecisionNode, without relating them to the corresponding KerML control behaviors, such as DecisionPerformance.