UML22 — Multiplicity of extensionLocation should be 1..1 instead of 1..*

The association extensionLocation is defined as follows (page 515):

"extensionLocation: ExtensionPoint [ 1..* ] An ordered list of extension points belonging to the extended use case, specifying where the respective behavioral fragments of the extending use case are to be inserted. The first fragment in the extending use case is associated with the first extension point in the list, the second fragment with the second point, and so on. (Note that, in most practical cases, the extending use case has just a single behavior fragment, so that the list of extension points is trivial.)"

It is not clear, what is meant by "behavioral fragments" (or "behavior fragments"). Neither term appears anywhere else in the spec. UseCase is a specialization of BehavioredClassifier and it can therefore have an optional classifier behavior (classifierBehavior) and own 0..* other behaviors (ownedBehavior). If "behavorial fragments" corresponded to "classifierBehavior", then the multiplicity of extensionLocation would have to be 1. If, however, it corresponded with "ownedBehavior", then it would be impossible to identify "the first fragment" because "ownedBehavior" is not ordered. In addition, it would be difficult to identify "the first extension point" because extensionLocation is not ordered either.

As stated above, "in most practical cases, the extending use case has just a single behevavior fragment". I therefore suggest to change the multiplicity of extensionLocation to 1..1

see above