FUML — Active class should not have to have classifier behaviors

Specification: Semantics of a Foundational Subset for Executable UML Models (ptc/2008-11-03)
Subclause: 7.2.2.2.3 Class

Constraint [1] “If isActive is true, then the class must be a behavior or have a classifier behavior” is too strong. It should at least be possible to have an abstract active class that does not have a classifier behavior. Indeed, the execution model for an active class still works even if concrete classes are allowed to have no classifier behavior (instances just don’t do anything once started), so perhaps the constraint is not necessary at all.

It is agreed that it is not necessary to require that an active class have a classifier behavior. However, it is still necessary to have a constraint requiring a class to be active if it has a classifier behavior.