Hibernate version:
3.0 beta 1

From what I see in the DTD, subclasses can only be used with class types and not dynamic-class types. Is this correct?

I am trying to use discrimination for a dynamic-class.

If by "Dynamic Class" you mean a dynamic components, then no. Actually, you can't use polymorphism at all with components in general, not just dynamic components, which is unfortunate. I'm constantly wanting to use a dynamic component in my classes. I've read posts that the Hibernate team wasn't aware of any good use cases for polymorphic components. I've got several!

I am not using components...I am actually using the new dynamic-class feature which essentially is a map.