- From: <Noah_Mendelsohn@lotus.com>
- Date: Tue, 21 Dec 1999 10:36:01 -0500
- To: ht@cogsci.ed.ac.uk (Henry S. Thompson)
- Cc: jjc@jclark.com, www-xml-schema-comments@w3.org
Yes, but it is absolutely essential to realize that in the latest layering of the specification it is the abstract components, such as type definitions and element declarations, that comprise a schema. The concrete syntax (e.g <schema>) represents a normative standard for the interchange of such definitions and declarations. For historical reasons, the current draft buries that fundamental distinction in the composition chapter. I assume that in upcoming rewrites we will make the distinction very clear. Specifically, we must explain the layering more clearly, and we must also make sure that all of the validity rules are properly associated with the appropriate layer of the specification. Note that the schema for schemas applies directly to the interchange format, so some of the constraints that it embodies must also be called out explicitly in the text, as many of them apply to the abstract schema as well as to the interchange syntax. I do agree with James that, at this point, the abstract syntax represents a confusing middle ground: it does not provide a rigorous introduction to the core definitions of the schema, and it is only indirectly related to the concrete syntax. I also agree with Henry's proposed direction for a resolution. ------------------------------------------------------------------------ Noah Mendelsohn Voice: 1-617-693-4036 Lotus Development Corp. Fax: 1-617-693-8676 One Rogers Street Cambridge, MA 02142 ------------------------------------------------------------------------ ht@cogsci.ed.ac.uk (Henry S. Thompson) Sent by: w3c-xml-schema-ig-request@w3.org 12/21/99 07:18 AM To: James Clark <jjc@jclark.com> cc: www-xml-schema-comments@w3.org, (bcc: Noah Mendelsohn/CAM/Lotus) Subject: Re: Abstract v concrete syntax James Clark wrote: > I find the split between abstract and concrete syntax impedes > understanding of the spec (it reminds me of 8879): I would find it much > more helpful to have just a concrete syntax. The 1991105 draft seemed > to me taking a step in the right direction by including concrete syntax > in the body of the spec using a similar notation to the XSLT spec; I was > surprised to find that these have disappeared in the 19991217 draft. I agree the current state is unsatisfactory. We got a modest amount of negative feedback about the concrete syntax paradigms in the previous two PWDs. They've been removed _pro tem_ in anticipation of a stylesheet working directly off of the schema for schemas, producing a concrete syntax summary more in keeping with schemas, but specific suggestions for how this should look are welcome. As for the abstract syntax, it will probably go, to be replaced by definitions of the abstract underlying types, which are much fewer and simpler, e.g. I think all we need here are simple type defn facet complex type defn content model element decl attribute decl key, unique, keyref any ht -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440 Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk URL: http://www.ltg.ed.ac.uk/~ht/
Received on Tuesday, 21 December 1999 10:30:09 UTC