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Re: Non-XHTML host languages for RDFa

From: Toby Inkster <tai@g5n.co.uk>
Date: Mon, 30 Nov 2009 10:25:25 +0000
To: Ivan Herman <ivan@w3.org>
Cc: RDFa Developers <public-rdf-in-xhtml-tf@w3.org>
Message-ID: <1259576725.2511.519.camel@ophelia2.g5n.co.uk>
On Mon, 2009-11-30 at 10:45 +0100, Ivan Herman wrote:
> Thanks Toby. These are important information if we work on non-HTML
> RDFa in the next incarnation of the RDFa group...
> As a comment on your question on SVG 1.2:
> [[[
> Should the predefined XHTML+RDFa keywords (e.g. "next", "prev") be
> supported in SVG?
> ]]]
> my answer is: I do not think so. And, actually... SVG1.2 Tiny is a
> Recommendation, so I do not believe that question is relevant until
> (and if...) the SVG group wants to update SVG1.2 Tiny. Ie, my feeling
> is that, in the note, we should make it clear that keywords should not
> be recognised in SVG...

I've done a little more digging into this question. The SVG Tiny 1.2 Rec

	RDFa enforces the further requirement that each value
	string must be a CURIE

Essentially they say "we don't enforce any requirements on the tokens in
this attribute, but RDFa needs them to be CURIEs". However, that's
factually incorrect. There are essentially two questions which emerge:

1. Is rel="next" OK to use in SVG. (I suspect the answer is yes.)

2. What should an RDFa processor do with it? (This is unclear.)

I suspect that the definitive answer should come from the SVG group.

> I was surprised not to see reference to the same issue for DataRSS. I
> must admit I never looked at that spec. Do they accept the xhtml
> keywords?

DataRSS has pretty similar language over their definition of @rel,
saying that it must contain CURIEs. However, unlike SVG Tiny 1.2, they
include a normative reference to the XHTML+RDFa spec. So this seems to
me to be a situation like:

1. Is rel="next" OK to use in DataRSS. (No.)

2. What should an RDFa processor do with it? (Process as per XHTML

Another interesting question about DataRSS is, given the following
(example from the "Understanding DataRSS" page of the SearchMonkey

  <y:adjunct version="1.0" name="com.yahoo.test">
    <y:meta property="tagspace:tags">tag 1 tag2 tag3 tag4</meta>
    <y:item rel="dc:subject" resource="http://photosite.com/img.jpg">
      <y:type typeof="media:Photo">
        <y:meta property="dc:creator">The Nameless One</meta>

What is the subject URI of the "tagspace:tags" triple? Should it be
taken from the <atom:id> element?

In version 0.3x of RDF::RDFa::Parser I may well include special support
for Atom, in which if an <atom:entry> element is encountered, a new
subject URI is set to the address given in <atom:id>, or a new bnode if
no <atom:id> child exists.

Toby A Inkster
Received on Monday, 30 November 2009 10:26:11 UTC

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