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Re: Type-assignment (was Re: Are we losing out because of grammars?)
- From: Murata Makoto <email@example.com>
- To: James Clark <firstname.lastname@example.org>
- 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
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.