Store a XML schema in a database

Hi all,

I have an XML schema (actually a class diagram exported to .xsd) that
I’d like to store in a database. I’m not interested in using it for
ORM, I just want to store the structure. For

 Auto
  |

|-----|
Truck Car

I don’t want to persist “Skylark” or “Explorer”, just the entities,
attributes, and relationships (and documentation).

I should mention this structure will be changing frequently for the
forseeable future.

Any ideas,

Todd