UML23 — "description" section of the Behavior metaclass

In the "description" section of the Behavior metaclass, there is the following sentence: "A classifier behavior is always a definition of behavior and not an illustration". The consequences of this statement should be explained and especially its impact on the capability of using Interactions for that purpose. A constraint should be added to the specification of the BehavioredClassifier metaclass.

In the UML 2.5 beta specification, this sentence still appears in Subclause 13.2.3, under the semantics of
“Behaviored Classifiers”. However, it is not clear that the sentence is really necessary at all. In the same
paragraph it says “For example, the classifierBehavior of a Collaboration (see sub clause 11.7) represents
emergent behavior of all the parts. . . ” Certainly, it is common to use Interactions as Collaboration classifier-
Behaviors, and it is not really clear what it means to “define” an emergent behavior anyway. The contrast
of “definition of behavior not an illustration” thus seems methodological, and the sentence can be removed
without changing the essential specification of classifierBehavior semantics.