I18N URIs in namespaces

We would like clarification about the use of non-US ASCII
characters in XML Namespaces e.g.

<eg xmlns:a="http://example.org/#Andr%c3%a9"
   xmlns:b="http://example.org/#Andr%C3%A9"
   xmlns:c="http://example.org/#André"
   a:a="a" b:a="b" c:a="a" />


Is this legal or illegal under XML 1.1 and why?


We are considering how we wish to support I18N URIs as labels within 
the RDF Graph and wish to make decisions conformant with other standards.


thanks

Jeremy Carroll on behalf of RDF Core WG