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Re: XHTML 2.0 - no interest in RDF/XML?

From: Masayasu Ishikawa <mimasa@w3.org>
Date: Fri, 16 Aug 2002 14:12:13 +0900 (JST)
Message-Id: <20020816.141213.74730171.mimasa@w3.org>
To: www-html@w3.org

Art.Barstow@nokia.com wrote:

> I was thinking that XHTML 2.0 could do something like SMIL and SVG
> have done with RDF/XML:
>  [1] http://www.w3.org/TR/2000/WD-smil-boston-20000622/metadata.html

It's an old draft, you should look at:


>  [2] http://www.w3.org/TR/SVG/metadata.html

If you look at both specifications closely, you'll realize that
neither of them really allow you to create (DTD-)valid SMIL/SVG
contents with embedded RDF/XML.  The content model of SMIL 2.0's
"metadata" element is EMPTY, and the content model of SVG's
"metadata" element is #PCDATA.  Neither is appropriate to accommodate
RDF/XML.  That's not really their fault, and I appreciate their
effort to accommodate RDF/XML.  DTD is just plainly incapable of
handling it appropriately.

However, as a result, verifying the document conformance of SMIL/SVG
contents becomes more complex, for example, in order to verify the SVG
document fragment conformance, you have to do the following:

  - if all non-SVG namespace elements and attributes and all xmlns
    attributes which refer to non-SVG namespace elements are removed from
    the given document, and if ... (other pre-processing), the result is
    a valid XML document.

  cf. http://www.w3.org/TR/SVG/conform.html#ConformingSVGDocuments

Validation is no longer a simple process, and we don't think we should
require our user community to do such a complex process.  XHTML's
document conformance is relatively simple, while there's a couple of
additional requirements beyond validity, validating an XHTML document
doesn't require complex pre-processing and peole can just use plain
validating XML processor.

Having said that, that's for XHTML 1.x.  I certainly appreciate
people's demand to be able to include more metadata in XHTML 2.0.
I just want to find a reasonable technical solution rather than
a hand-waving statement or requiring complex pre-processing.
We always welcome technically-feasible proposal.

Masayasu Ishikawa / mimasa@w3.org
W3C - World Wide Web Consortium
Received on Friday, 16 August 2002 01:12:16 UTC

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