XML Schema Question

[shaft]

I have a question about xml schemas and EA.

What I want is:
1.  B & C are children of A (Generalization = xml "extension")
2.  X can contain any derivitive of A (like B or C).

So I tried creating an association from X back to A, which would work in UML and code.  But when I generate a document from the schema like:
<X>
<B>...</B>
<X>

I get an error saying X is expecting an element of type A.


Is there anyway to allow complex type X to contain any derivitive of A, without creating a link directly to each derivative (i.e. X is associated to B&C).

The number of elements derived from A is going to continue to grow, and I don't want to have to create explicit links for each one.  Thats just ugly.

Thanks,
Jeff