Re: Annotation issue: constraints on pattern with a:attributeType

[James Clark <jjc@jclark.com>]

> (e) allow <text/> only

One problem with this is that the annotation spec is optional.  Thus users 
are faced would a difficult choice:

(a) use <data type="NCName"/> and get lexical checking with validators that 
support XSD but get no cross-reference checking

(b) use a:attributeType and get full checking on validators that support 
a:attributeType but get no lexical checking on validators that don't 
support a:attributeTYpe but do support XSD

A user should be able to get both

- lexical checking (as an NCName) with any validator supports XSD

- cross-reference checking with any validator that supports a:attributeType

Another problem is that it is quite useful to be able to apply regexs to 
ID/IDREFs.  For example, it is a common technique to divide up the ID/IDREF 
space by using prefixes.  For example, IDs of bibliographic references 
might start with "b".  You might have a bib element that defined 
bibliographic entries and a bibref element that referenced them.  Then on 
the ID/IDREF attributes on those elements you would want to apply the regex 
"b.*".

James