XSD: Conditional type definition

Dear list,

   I'm relatively new to XSD and would like to perform the following:


I have an XML-element like this:
<anElement type="ONE">
   <ONEelement />
</anElement>

<anElement type="TWO">
   <TWOelement />
</enElement>

So there is the "anElement" and depending on its type the subelements 
are different. Is there a way to declare this behaviour with XSD?

TIA,
   Ralph