[news.eclipse.modeling.mdt.ocl] How to check the types of containment?

[Gilbert Mirenque <formatzeh@xxxxxx>]

Hello,
imagine I have class defined (CompositionModel) in my meta model which
has a containment reference (1..*) to an abstract class (AbstractModel).
I have several concrete classes (ModelA, ModelB, ...) inheriting from
that abstract class. Now I want to write an ocl constraint for
CompositionModel expressing that every concrete class can only be
contained once in the CompositionModel class. How can I express this? I
have to count the contained types for every ModelA, ModelB, ... anyway.
Can you help me?

best regards,
Gilbert