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Re: xmlns in HTML5

From: Ian Hickson <ian@hixie.ch>
Date: Thu, 16 Jul 2009 11:06:22 +0000 (UTC)
To: Dan Brickley <danbri@danbri.org>
Cc: Toby Inkster <tai@g5n.co.uk>, Manu Sporny <msporny@digitalbazaar.com>, RDFa <public-rdf-in-xhtml-tf@w3.org>
Message-ID: <Pine.LNX.4.62.0907161059140.12284@hixie.dreamhostps.com>
On Thu, 16 Jul 2009, Dan Brickley wrote:
> On 16/7/09 11:20, Ian Hickson wrote:
> > On Thu, 16 Jul 2009, Toby Inkster wrote:
> > > Ian Hickson wrote:
> > > 
> > > > Authors must not use elements, attributes, and attribute values that
> > > > are not permitted by this specification or other applicable
> > > > specifications.
> > > >   -- http://www.whatwg.org/specs/web-apps/current-work/#semantics-0
> > > Which "other specifications" are "applicable"?
> > 
> > Pretty much any that claim to be and that the people affected agree are
> > applicable. If an RDFa specification said that text/html could have
> > arbitrary xmlns:* attributes, then the HTML5 specification would (by
> > virtue of the above-quoted sentence) defer to it and thus it would be
> > allowed. Similarly, Microsoft could write a spec and claim<marquee>  is
> > valid, as well as<msword>  and<excel>.
> > 
> > Of course, if a community doesn't acknowledge the authority of such a
> > spec, and they _do_ acknowledge the authority of the HTML5 spec, then it
> > would be (for them) as if that spec didn't exist. Similarly, there might
> > be a community that only acknowledges the HTML4 spec and doesn't consider
> > HTML5 to be relevant, in which case for them, HTML5 isn't relevant.
> > 
> > This is how specs work. :-)
> 
> How would you expect a validator for such a flexible format to work?

The same way validators work now. The validator implementors decide which 
specs they think are relevant to their users.

The W3C CSS validator, for instance, can be configured to check against 
CSS2.1 rules or against SVG rules about CSS. It can't be configured to 
check against CSS2.1 + the :-moz-any-link extension, because the CSS 
validator implementors have decided that CSS2.1 and SVG are relevant, but 
not the Mozilla CSS extensions. (In this case, the latter don't have a 
formal specification, but they could do and the point would still hold.)

The W3C HTML validator, similarly, supports checking a document against 
XHTML 1.1, or XHTML + RDFa, or XHTML + SVG, but doesn't support checking 
it against XHTML + DOCBOOK. So its implementors have decided that RDFa, 
SVG, and XHTML are relevant, but DOCBOOK is not.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Thursday, 16 July 2009 11:07:04 GMT

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