DTD for Schemas (Non-normative) comment

In the DTD for Schemas (non-normative) there is a comment with the
"attribute" ELEMENT.  The comment is <!-- name and use are mutually
exclusive -->
I can't find any normative reference to this.  The examples in
Structures 4.3.1 have both use and name ( which seems fine to me ), but
I don't understand the comment above.
Any pointers?

cheers,
michael.