W3C home > Mailing lists > Public > xmlschema-dev@w3.org > April 2001

Re: Mixing schemaLocation and noNamespaceSchemaLocation?

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>
Message-ID: <Pine.LNX.4.21.0104132024030.11380-100000@tugela.dsl.net>
> > 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

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


Received on Friday, 13 April 2001 16:06:35 UTC

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