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Re: ISSUE-24: Proposal for dealing with case-insensitive terms in the XHTML vocabulary

From: Toby Inkster <tai@g5n.co.uk>
Date: Wed, 14 Jul 2010 10:03:03 +0100
To: Shane McCarron <shane@aptest.com>
Cc: RDFa WG <public-rdfa-wg@w3.org>
Message-ID: <20100714100303.1bf42f8f@miranda.g5n.co.uk>
On Tue, 13 Jul 2010 17:01:52 -0500
Shane McCarron <shane@aptest.com> wrote:

> In XHTML+RDFa 1.1 we should say:
> 
>     When referencing TERMs in the vocabulary at
>     http://www.w3.org/1999/xhtml/vocab, TERMs must be mapped to lower
> case.

Does this also cover the case of the empty prefix? According to my
reading of XHTML+RDFa 1.0, given the following:

	rel="Next"
	rel=":Next"

The first is mapped to lower-case; the second is treated
case-sensitively. This is because the former is a term and the latter
is a CURIE.

I suggest we retain this distinction, as there do exist mixed-case
terms defined in the XHTML vocabulary (though they're not used by RDFa
currently).

Ivan wrote:

> 2. in RDFa+XHTML (and I presume in RDFa+HTML5) there is a a default
> @vocab, namely http://www.w3.org/1999/xhtml/vocab# and, if this is the
> one in effect, then terms are interpreted in a case insensitive way,
> ie, terms must be mapped on lower case.

Personally I'd ditch that too -- you get too many junk results. Better
to say that the default vocabulary in (X)HTML+RDFa is null.

Otherwise you'll end up with having to deal with rel values from
Microformats, etc. The problem with that it that Microformats have
their own ways of determining what the "subject" is for a rel; applying
RDF's @about/@src/chaining rules doesn't work well.

To handle the case of rel="next", rel="prev", etc define a default
*profile* for XHTML+RDFa, and have that profile define those terms
case-insensitively. (The profile SHOULD be hard-coded in XHTML+RDFa
parsers; authors MAY include an explicit @profile attribute referencing
the default profile.)

This means that parsers need to internally allow profiles to define
both case-sensitive and case-insensitive terms, though we may decide
not that profiles other than the XHTML vocab are not privileged to
declare case-insensitive terms.

This solution allows us to pick up "our" @rel terms but skim safely
over the @rel terms used by Microformats, Javascript libraries, etc.

-- 
Toby A Inkster
<mailto:mail@tobyinkster.co.uk>
<http://tobyinkster.co.uk>
Received on Wednesday, 14 July 2010 09:04:10 GMT

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