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Re: Henri's RDFa statements in the XHTML2 FAQ

From: Henri Sivonen <hsivonen@iki.fi>
Date: Wed, 8 Jul 2009 19:55:32 +0300
Message-Id: <BDB250C6-9A48-4CA1-AA0D-0D99B4612AF2@iki.fi>
To: public-rdf-in-xhtml-tf@w3.org
> Just throwing this out there in case some of you haven't seen it yet:
> http://hsivonen.iki.fi/xhtml2-html5-q-and-a/
> In it, Henri makes the following assertions:
> > What happens to RDFa?
> >     RDFa (in XHTML but not in HTML!) is a W3C Recommendation and, as
> > such, doesnít need any terminating action per the W3C Process. Itís
> > unclear if another WG will develop further RDFa specs.
> We will be developing further RDFa specs - whether it happens inside  
> the
> W3C or outside the W3C is still up in the air.

Interesting. I hadn't considered the WHATWGish going outside the W3C  
option for RDFa. I think "unclear" is fair given "still up in the air".

> > Do semantics round-trip in an HTML5 to XHTML5 to HTML5 conversion?
> >    Yes, provided that the first HTML5 input is valid and you donít
> > ascribe semantics to characters that arenít allowed in XML (such as
> > form feed or U+FFFF). Note that RDFa isnít valid in either HTML5 or
> > XHTML5 as currently drafted.
> We are certainly addressing all of the issues raised during the past
> several months[1]. Henri failed to mention that this work continues  
> and
> that we are making progress.

I included "as currently drafted" to avoid suggesting it can't change.

> > What about XHTML5 to HTML5 to XHTML5?
> >    Not if namespace-based extensibility is used. However, in the
> > common case, the conversion chain does round trip if the input is
> > valid XHTML5 + SVG 1.1 + MathML 2.0 (this excludes RDFa), doesnít  
> use
> > namespaces from outside those specs (Itís debatable if the previous
> > condition already covers this.), xml:space on HTML elements is not
> > considered to affect semantics and relative URLs are rewritten so  
> that
> > xml:base attributes can be removed without breaking links. (Answer
> > clarified/corrected 2009-07-07.)
> My understanding is that XHTML5 and SVG 1.1 contain namespace  
> support -
> so why is RDFa excluded from those languages on the basis of using
> namespaces and CURIEs in attributes (other than Henri's personal
> preferences)?

Oh please. The "personal preferences" line again.

XHTML5 doesn't currently make the RDFa attributes valid on HTML  
elements. Even if it did, you can't round trip via HTML5, because  
namespace declarations aren't serializable as HTML5 and RDFa isn't  
defined for HTML (in the present tense).

> > Are the semantics of HTML5 extensible?
> >    Yes. With microdata.
> It's difficult to believe that WHATWG doesn't have a bias (as Ian has
> asserted repeatedly) when Microdata is being proposed as a solution.
> Microdata clearly does not have a test suite, does not have a set of
> implementations, and does not have much in the way of implementation
> feedback. RDFa has all of those in spades, but gets absolutely no
> mention as an alternative approach.

Rightly or wrongly, it's not an approach supported by the HTML 5 spec  
today (or the day before yesterday). Note that I didn't mention  
microformats, either, even though those are allowed as currently  

> Henri's "FAQ" attempts to assert that RDFa is, and will continue to  
> be,
> an incompatible technology with HTML5 and XHTML5.

That's an unfair claim. My blog post only asserts things about RDFa in  
round-tripping in the present tense.

Henri Sivonen
Received on Wednesday, 8 July 2009 16:56:24 UTC

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