xml-dev - Re: XML doc valid against more than one DTD / Schema

["Frank Boumphrey" <bckman@ix.netcom.com>]

Charles,
the best way to do this is to modularize your DTD. If you have a letter
module then you can even use your full DTD to validate it. You must change
your DOCTYPE declaration of course. In our medical DTD we have a
hierarchical module (a la DocBook) and then modules for all the common tasks
performed by a medical record.

Frank

----- Original Message -----
From: Charles McCay <charlie@ramseysystems.co.uk>
To: <xml-dev@xml.org>
Sent: Friday, April 07, 2000 11:17 AM
Subject: XML doc valid against more than one DTD / Schema


> I am working with a complex DTD for a full medical record, and want to
> define a simpler subset that could be used just for discharge letters.
This
> would include restricting some of the enumerated attributes, and providing
> FIXED values for others, and removing some of the optional elements.
>
> What I would like to be able to do is to indicate that a document is valid
> against both the restricted DTD and the full one, so that the receiving
> system can validate it using whichever one they have.
>
> Such simplified documents could be used as a stepping stone towards
> implementing a richer data exchange using the full DTD, reducing the cost
of
> getting started  while having forward compatibility.
>
> Also if DTD/schema editors could easily validate that their cut-down
> document design defined a true subset of the documents valid under a
larger
> and more complex document design, then the risk of having multiple
"similar
> but not quite the same" documents would be reduced.
> Conditional blocks in the full schema will not work, because that assumes
> that the full schema can be amended whenever a new subset is wanted.
>
> It is far easier to persuade a supplier to implement a standards based
> interface where
> they can do it in an incremental fashion, and so short schema that only
> cover part of the
> full information model are a good deal more attractive that having to deal
> with everything at
> once.  However once they have done the work to support the full model,
they
> want the payback
> of not having to modify their work to support different subsets.
>
> Looking at the W3C spec of schemas there seems to be some hope.  It
appears
> possible to validate a document against a schema other than the one
> associated with the default namespace of the instance document, but there
is
> not a mechanism for saying that a document is valid under two namespaces.
> It appears that restrictions will be available to define the simplified
> version, but what this will not deliver is an easy to read short document
> (schema) for the simplified document definition.  This will still be
> referencing the full document, if anything adding the confusion of the
> implementer.
>
>
> Any suggestions or corrections more thank welcome
>
> --
> Charlie McCay, charlie@RamseySystems.co.uk
> Ramsey Systems Ltd, 23D Dogpole, Shrewsbury, Shropshire SY1 1ES
> tel 01743 232278 / fax 01743 232295
>
>
>
>
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