We recently changed MEX so that it references RFC 3986 for URI comparison.
Other specs have xs:anyURI's (e.g. dialects) too and we should probably say the
same thing for those specs.  However, rather than adding text to each
URI definition, we should just add a sentence to each "Compliance"
section that says:

*****
Unless otherwise noted, all URIs are absolute URIs and URI comparison MUST be 
performed according to [RFC 3986] section 6.2.1.
*****
And add the appropriate RFC3986 ref.


This applies to all specs - they all have some xs:anyURI defined.

And for mex, remove:
Dialect is an absolute URI. URI comparisons are performed according to [RFC 3986] section 6.2.1.

and

Identifier is an absolute URI. URI comparisons are performed according to [RFC 3986] section 6.2.1.