The business of mixing "simple content" (e.g. text) with elements is quite
fraught in in the derivation mechisms within W3C XML Schema.
As Pete points out below, mixed="true" does not constrain the position or
number of text nodes.
There is also some real confusion - even amongst the authors of the spec -
as to whther or how you can start with a "mixed" supertype, and retstrict
that down to a specific simpleContent derived type.
i.e. - if all the basic elements are specified to be type="text"
- i.e. mixed -
then it is probablly not possible to derive a type by restriction whose
simpleContent is a "date".
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>
> Date: Thu, 7 Mar 2002 13:29:42 -0000
> From: Pete Johnston <[log in to unmask]>
> Subject: Re: Public Comment on DC-simple XML Schema
> declaration within OAI
>
> Carl,
>
> > 1. Do not spec an exact list of sub-elements. Allow that to
> > be open territory. 2. Mandate in the schema that each element
> > have a dumb-down value. Sigge's earlier mail stated this with
> > the tag <simpleValue> but I don't think that this syntactic
> > sugar is actually necessary.
>
> I think some sort of explicit marking of either the "complex value" or
> the "simple value" may be required because the text content model (I
> think) allows "mixed content" so there could be any number of
> text nodes
> interspersed amongst child elements within a DC element.
>
> I'm torn between your option 2 and option 3.
>
> I'm just a little bit worried that if we go the option 2 route, we're
> attempting to reinvent (parts of) RDF a bit hastily.
>
> If we can satisfactorily address the definition of a second
> schema which
> uses import or redefine to provide the "tightening" of a loose base
> content model (which we have now) for e.g. OAI's
> "simple-DC-values-are-strings" model, I think that feels a better
> solution to me.
>
> Pete
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