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Re: @rel syntax in RDFa (relevant to ISSUE-60 discussion), was: Using XMLNS in link/@rel

From: Julian Reschke <julian.reschke@gmx.de>
Date: Thu, 05 Mar 2009 16:44:35 +0100
Message-ID: <49AFF363.6040306@gmx.de>
To: Manu Sporny <msporny@digitalbazaar.com>
CC: Maciej Stachowiak <mjs@apple.com>, Mark Nottingham <mnot@mnot.net>, "www-tag@w3.org WG" <www-tag@w3.org>, HTMLWG WG <public-html@w3.org>, RDFa mailing list <public-rdf-in-xhtml-tf@w3.org>, public-xhtml2@w3.org
Manu Sporny wrote:
> ...
> Here are a few:
> 
> hReview, xFolk, hCard, hCalendar, hAudio and other Microformats that use
> rel-tag, rel-purchase, rel-nofollow, rel-directory, rel-enclosure,
> rel-home, and rel-payment
> 
>  * hReview uses rel-tag for tags and scalar tags
>  * xFolk uses rel-tag to build a distributed remote resource tagging
>    construct
>  * hCard can use rel-tag for categories
>  * hCalendar can use rel-tag for categories
>  * hAudio uses rel-purchase for purchase information, rel-enclosure for
>    downloadable files.

Thanks for the pointer. I'm using hCard myself, but haven't used rel 
values for it yet.

> In practice, @profile is not used and thus the semantic meaning of these
> terms is ambiguous and only truly "understood" by a Microformats parser.
> A non-Microformats parser would ignore these @rel values, thus creating
> a situation where a Microformats-aware parser would extract different
> meaning from a document vs. a non-Microformats-aware parser. The
> situation is the same with a GRDDL-aware parser vs. a non-GRDDL-aware
> parser.
> 
> However, I don't think that's Julian's point. I believe that his point
> is that, because of CURIEs, you have a two-stage process instead of a
> one-stage process.
> 
> For CURIES, you must:
> 
> 1. Read the value in @rel.
> 2. Lookup the prefix mapping and append the reference to the prefix.
> 
> For GRDDL, you must:
> 
> 1. Read the value in @rel.
> 2. Process the @rel value via XSLT.

Hm, no. Unless I'm missing something.

In GRDDL, you pass the document to the specified transformation, and end 
up with a bunch of RDF.

> For Microformats, non-CURIEs, etc., you must:
> 
> 1. Read the value in @rel.
> 
> Is that your issue, Julian? That because of CURIEs/RDFa, you have to do
> more now to determine what @rel really means?

Yes. Using a safe-CURIE wouldn't have prevented that, but at least it 
wouldn't break URIs in rel values.

BR, Julian
Received on Thursday, 5 March 2009 15:45:22 GMT

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