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RE: ISSUE-76: If we fixed namespaces, does RDFa still have problems?

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Wed, 16 Dec 2009 02:02:41 +0100
To: Toby Inkster <tai@g5n.co.uk>
Cc: "Ennals, Robert" <robert.ennals@intel.com>, Maciej Stachowiak <mjs@apple.com>, "public-html@w3.org" <public-html@w3.org>
Message-ID: <20091216020241723662.3a782d96@xn--mlform-iua.no>
Toby Inkster, Tue, 15 Dec 2009 09:25:22 +0000:
> On Tue, 2009-12-15 at 04:15 +0100, Leif Halvard Silli wrote:
> 
>> I think, to make RDFa "native" to HTML and simple to use, then a
>> vocabulary for the HTML namespace could be useful. 
>> 
>> It should be simpler to use this vocabulary than other vocabularies. 
>> Either because it could be used without any prefix at all. 
> 
> XHTML+RDFa 1.0 already has this.

I have long thought it interesting that XHTML+RDFa 1.0 offers most of 
what we cannot agree to add in HTML 5: RDFa (of course), 
namespaces/colon prefixes, especially prefixes in attributes, more 
compatible @rev/@rel vocabularies. That _may_ (and I guess, mostly) is 
served as text/HTML. And it is here _today_.  The cat is out of the 
sack.

> The default prefix is:
> 
> 	http://www.w3.org/1999/xhtml/vocab#
> 
> And it contains a bunch of terms useful for describing (X)HTML
> documents. It has terms like "chapter", "appendix", "contents", "index",
> "glossary", "copyright" and "license". CURIEs in the default prefix are
> written with an empty first part, e.g. the second CURIE in this
> attribute:
> 
> 	rel="dc:license :license cc:license"
> 
> Within @rel and @rev in fact, terms from the current XHTML vocabulary
> are treated as case-insensitive keywords, so the leading colon isn't
> needed either.

Is it, in principle, permitted to define and use a prefix also for the 
default vocabulary?

> I'd certainly like to see the XHTML vocabulary expand to cover other
> terms useful for describing typical XHTML documents. Authorship, dates,
> topic/keyword, title and description properties seem natural additions.

Perhaps the microdata vocabularies, or a derivate, could be a candidate 
vocabulary?
 
> The vocab itself can be added to without needing any changes to RDFa,
> though the new terms would not be recognised as case-insensitive
> keywords by RDFa 1.0 processors.

What decides whether new terms will be interpreted as case-insensitive 
or not? 

>> These HTML namespace vocabularies would then also be possible to use 
>> not only in HTML documents, but also in other mark-up languages.
> 
> The SVG Tiny 1.2 Rec (which includes RDFa) unfortunately has little to
> say on whether the default prefix and keywords apply to SVG. In my
> parser, I decided that these should work the same as XHTML. Hopefully,
> clearer guidance to using RDFa in non-XHTML host languages will be one
> of the things an RDFa WG will deliver.
> 
> When SVG or MathML are used *within* XHTML, I certainly think it's a
> good idea to apply the XHTML rules throughout. Switching rules for
> document fragments does not seem desirable.

I was not aware of this unclarity. I agree with your conclusion.
-- 
leif halvard silli
Received on Wednesday, 16 December 2009 01:03:17 UTC

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