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Re: Type-assignment (was Re: Are we losing out because of grammars?)
- From: Murata Makoto <mura034@attglobal.net>
- To: James Clark <jjc@jclark.com>
- Date: Fri, 02 Feb 2001 21:09:49 +0900
James Clark wrote:
> Yes, indeed. ID/IDREF is a very interesting problem for TREX. However,
> although type-assignment can be used to deal with this, it's not quite
> solving the right problem. For ID/IDREF, I want to know whether I can
> assign datatypes unambiguously not whether I can assign labels (in the
> RELAX sense) umabiguously. A grammar may be ambiguous with respect to
> assignment of labels, but unambiguous with respect to assignement of
> datatypes.
To distinguish the two types of ambiguity, we need two terms. How about
ambiguity of datatype assignment and ambiguity of interpretation?
Kawaguchi-san's algorithm for detecting ambiguity of interpretation looks
cool. Is it possible to detect ambiguity of datatype assignment by
examining a TREX pattern?
> My current thinking is that the ID/IDREF approach to uniqueness
> constraints doesn't really scale. For example, there's no way I can see
> to make it handle multipart keys. ID isn't purely a datatype in the same
> way that NMTOKEN is: making an attribute have type ID has side-effects
> on the validity of other attributes that making an attribute have type
> NMTOKEN does not.
Agreed. But I do not want to miss ID. It is so common right now, and
people would like to use ID as a datatype in writing grammars or schemas.
>I think it's better therefore to move to a completely
> different approach to handling uniquessnes and cross-reference
> constraints, more along the lines of the identity constraints in W3C's
> XML Schemas.
Or, we can use Schematron together with RELAX/TREX.
Cheers,
Makoto