UMLR — surface notation for state machines

The surface notation for state machines allows to show, on the line representing a transition, certain key actions that will be performed by the behavior associated with the transition. This is straightforward, when the behavior is an activity (as those actions can be referenced). However, for any other behavior, e.g., an opaque behavior, we need a method of (in the metamodel) show that this behavior does contain certain actions. Note that this should not give an alternative way of defining sequences of actions; rather, this should merely state that this behavior will contain the exhibited actions but it may contain many more. Those actions would merely give a means of representing the graphical constructs in the metamodel