UML241 — UML2 Superstructure - profiles

From the current spec I really can't work out what to implement. For what
it's worth, this is what I think should be there:
Properties can be typed either by MOF primitive types (the ones used in the
UML metamodel, such as string, boolean and enumeration and subtypes), or by
UML metaclasses. This is not only consistent wth UML 1.x, it also is likely
to be the most easily implemented - vendors already need to provide a UI for
editing boolean properties etc. and editing properties typed by metaclasses
is easy - just use a list control to reference existing model elements.
The spec seems to state that properties can typed by arbitrary model
elements.("However, it is possible to have
associations between ordinary classes, and from stereotypes to ordinary
classes")
How is a tool supposed to know what to do with it - it looks like the
current spec allows a stereotype property to be typed by something like an
Actor, not the actor metaclass, but some specific actor - what use is that?
The more I read about this the more I'm convinced that we will never get
interoperability, unless we tighten the rules as I suggested above.