- From: Ian Stokes-Rees <ijs@decisionsoft.com>
- Date: Fri, 13 Apr 2001 21:05:40 +0100 (BST)
- To: "Henry S. Thompson" <ht@cogsci.ed.ac.uk>
- cc: "Arnold, Curt" <Curt.Arnold@hyprotech.com>, "'xmlschema-dev@w3.org'" <xmlschema-dev@w3.org>
> > Isn't the proper way of thinking about this that there is only one > > schema per namespace and that there are multiple schema documents > > describing that namespace? > > Since schemas and schema documents are all there are, and we > schema-validate _an_ instance with _a_ schema, it must be the case > that we may have more than one namespace per schema. What I think > the useful summary is that in any case where multiple schema documents > are used to describe a namespace, a single schema document which > <include>s them all should also be provides, so that instances and > other schema documents can use a single URI to identify them. I have to admit that this is a bit of a revelation to me, so I want to confirm: Assertion #1: A particular instance document always corresponds to either no schema or one schema, but not multiple schemas. Assertion #2: That schema is specified by some combination of the instance document and the processing application. Assertion #3: That schema may consist of multiple namespaces (since an instance document can consist of multiple namespaces). Assertion #4: One schema document may define a subset of at most one namespace. (that subset may be the entire namespace, or may be no namespace, in the case of "null namespace" schema documents). Assertion #5: A single schema document must use <any namespace="..."/> to tie into other schemas. Assertion #6: An instance document must use xmlns:xxx="..." attributes to indicate changes in the namespace of portions of the document. I state these as assertions since I accept there may be errors or omissions. The basic idea is that a set of instance documents can be defined to correspond to a schema. That schema may cover multiple namespaces. A schema document may only define a subset of a particular namespace (or no namespace), but may be combined with others schema documents in other namespaces to exhaustively define a single schema. Regards, Ian.
Received on Friday, 13 April 2001 16:06:35 UTC