Section 10.1.1 (InstanceSpecification) has an operation getContainers with a postcondition returning potentially multiple instances linked at the owning end of composite associations. This is disallowed under UML semantics, making SMOF not a subset of UML semantically. Since SMOF is mainly concerned with multiple and dynamic classification, which does not affect issues of conflicting ownership (any more than multiple composite properties on a classifier do under the current MOF), it is not necessary for SMOF to address issues of ownership.

SMOF restricts itself to dynamically classifying elements, and requires links to have a single static Association. The problem with that will show up as soon as we want to use SMOF for profiles. We might, for example, have metaclasses C1 and C2 connected by an association A. Apply the profile and it automatically infers that C1 needs also to be classified by P1 and C2 by P2 – and A by B. But SMOF doesn’t allow the “A by B” part.