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Re: RDFa Lite and non-RDFa @rel values [Final Take?]

From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Wed, 25 Apr 2012 18:42:17 -0400
To: Alex Milowski <alex@milowski.com>
CC: RDFa WG <public-rdfa-wg@w3.org>
Message-ID: <C1D245D9-4AB8-4B17-8282-C6EA391EBE32@greggkellogg.net>
On Apr 25, 2012, at 2:50 PM, Alex Milowski wrote:

> On Wed, Apr 25, 2012 at 1:50 PM, Gregg Kellogg <gregg@greggkellogg.net> wrote:
>> 
>> The thing is that @rel remains a valid RDFa 1.1 property (not RDFa 1.1 Lite conformant, but a conforming processor MUST process @rel). Adding a rule, specifically for HTML+RDFa 1.1 (which includes both HTML5 and XHTML5), that removes these "junk" link relations from consideration solves the problem for the typical junk link relation terms.
>> 
> 
> As specified, I fail to see how the current HTML+RDFa 1.1 document
> indicates any handling of documents served with the media type
> application/xhtml+xml.  If all you have is the content-type header and
> the XML (XHTML) document, how exactly do you choose between XHTML+RDFa
> 1.1 and HTML+RDFa 1.1 ?  If that was well-defined and rational to use,
> that would go a long way in making this easier to use.

It's even worse. Given text/html, how to you decode for microdata, HTML+RDFa or Turtle+RDFa (yes, it exists [1]). The fact is, you either need to decode against all formats, or have some a-priori knowledge to pick the proper processors.

application/xhtml+xml adds in the possibility of XHTML+RDFa 1.0 and XHTML+RDFa 1.1, for which other indicators (DOCTYPE, @version) need to be used.

The HTML+RDFa doc does need to clarify that it is applied to text/html as well as application/xhtml+xml, but I think this is implied by piggy-backing on the HTML spec, which already indicates that supports both mime types. Note that microdata doesn't go out of it's way to say it supports both text/html and application/xhtml+xml either, as it's assumed from the HTML spec.

I would clarify the HTML+RDFa 1.1 spec User Agent Conformance with something like the following:

[[[
HTML+RDFa documents should be labeled with Internet Media Types "text/html" or "application/xhtml+xml" as defined in [RFC3236].
]]]

There should also be an indication that XHTML mode HTML+RDFa 1.1 documents can be distinguished from XHTML+RDFa 1.1 documents by the lack of an XHTML DOCTYPE or @version.

I created ISSUE-137 to track this on your behalf.

Gregg

[1] http://dvcs.w3.org/hg/rdf/raw-file/default/rdf-turtle/index.html#in-html

> -- 
> --Alex Milowski
> "The excellence of grammar as a guide is proportional to the paucity of the
> inflexions, i.e. to the degree of analysis effected by the language
> considered."
> 
> Bertrand Russell in a footnote of Principles of Mathematics
> 
Received on Wednesday, 25 April 2012 22:43:10 GMT

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