PlanDefinition.action.definition[x] list issues

If plandefinition is to be used for non clinical aspects, such as the master schedule for inspections and other procedures then the PlanDefinition.action.definition[x] list either becomes extensible (in which case we add procedure) or procedure needs to be added to the list otherwise we have to add an intermediate level (activitiydefinition) that adds no  value solely to link the procedure to the plandefinition.