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

From: Manu Sporny <msporny@digitalbazaar.com>
Date: Thu, 05 Mar 2009 10:32:48 -0500
Message-ID: <49AFF0A0.9070508@digitalbazaar.com>
To: Julian Reschke <julian.reschke@gmx.de>
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
Julian Reschke wrote:
> Ben Adida wrote:
>> Maciej Stachowiak wrote:
>>> Microformat-defined rel and class values have their usual semantics
>>> regardless of whether one links a GRDDL transform converting them to
>>> RDF.
>>
>> How is mnot going to figure out what those semantics are to generate a
>> proper link-type header? Will all microformats be added to the IETF
>> link-type registry?
> 
> Could you clarify which specific microformat you're concerned with here?

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.

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.

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?

-- manu

-- 
Manu Sporny
President/CEO - Digital Bazaar, Inc.
Absorbing Costs Considered Harmful
http://blog.digitalbazaar.com/2009/02/27/absorbing-costs-harmful
Received on Thursday, 5 March 2009 15:33:41 GMT

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