[news.eclipse.modeling.mdt.uml2.uml] How to specify XOR generalisation?

[Florian Georg <florian.georg@xxxxxxxxxx>]

Hello,
I'm wondering how to express a xor generalization in the UML2 model.

e.g. Person <|-- Natural Person, Legal Person
Meaning that a person can be a natural or legal person, but not both at 
the same time.

Do I have to use OCL constraints for that, or are there other 
possibilities (e.g. generalization Sets) to express this relation in a 
model?

thanks in advance,
Florian