Stand-alone AssociationClass -MDG?

[Paolo F Cantoni]

Anybody know how to create a stand-alone AssociationClass in an MDG Technology?

All my attempts have so far failed.  If I extend a Class metaclass, all works fine, If I extend the AssociationClass metaclass, it creates the Association arc AND related AssociationClass vertex (which is to be expected).

I just want to create a stand-alone AssociationClass (because I want to manage N-ary Associations).

I think I'd like a metaattribute (something like: _standalone) that would create the AssociationClass vertex only - without the accompanying arc.

TIA,
Paolo