Feature Request: wildcard - any element but these

I'd like to have a content model of the sort:

   (x*, anything-but-x*)

Currently, this can't be encoded because there is no way to specify the
wildcard.

Using ##other comes close but doesn't quite work.

What would be nice is:

    <xs:any>
    <xs:except name="p:x"/>
    <xs:except namespace="http://www.somewhere.org/schema/bad"/>
    </xs:any>

That is, I want the ability to list exceptions:

    * by element name--not necessarily one with an element declaration
      as there may be no schema.
    * by namespace name


-- Alex Milowski  

"The excellence of grammar as a guide is proportional to the paucity of 
the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics