UML14 — UML RTF 1.4 Issue: State constraint on host object

States currently do not model the conditions required for an
object to be in a particular state. A constraint note can be
linked to a state, but there is no specification of when the
constraint should be tested. It could be tested when the object
enters the state, leaves the state, or at any other time. Even if
this were unambiguous, the consequence of violating the constraint
is not defined, namely, to transition the machine to a state that
has a constraint satisfied by the object. This might be modeled
as a change-event trigger on an exiting transition, but it would
be redundant with the constraint recorded on the state and with
triggers on other transitions leaving the state, thereby impairing
maintainability.

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