SPTP — p. 99:

"In the domain view point describing the concurrency feature, two specific kinds of service are introduced: DeferredService and ImmediateService. I propose to add:
IgnoredService
A kind of service instance that is ignored if the receiving object is not able to handle it when it receives it.
RejectedService
A kind of service instance that is rejected if the receiving object is not able to handle it when it receives it. The rejection of a call will also raise an exception that can be catch either by the sender of the stimuli or by the system itself."