State
A State models a situation during which some (usually implicit) invariant condition holds.
For behavior StateMachines, States are internal elements hidden from view of external parties. However, the states of ProtocolStateMachines are intended to be exposed to the users of their context Classifiers. A protocol State represents an exposed stable situation of its context classifier: when an instance of the Classifier is not processing any BehavioralFeature, external parties interacting with this instance can always know its State configuration.