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Summary of current state of ISSUE-135

From: Stéphane Corlosquet <scorlosquet@gmail.com>
Date: Thu, 6 Sep 2012 02:26:43 -0400
Message-ID: <CAGR+nnHdHJpJGNGDkv9WLEW2OrYRvBPsYr8J5n=x6qbrq4K1mg@mail.gmail.com>
To: RDFa WG <public-rdfa-wg@w3.org>
The aim of ISSUE-135 is to prevent a non-RDFa @rel to disable the new
behavior of @property in RDFa+HTML5. In HTML5, @rel is used for many
purposes ([1] and [2]), many of them are irrelevant to RDFa. When HTML
authors use these values in @rel, they most likely don't do it with RDFa in
mind, and in this context the behavior of @property should not change when
a non-RDFa @rel is added to the same element.

In other words, the following two paragraphs should generate the same
<p vocab="http://schema.org/" typeof="Person">
   My name is <a href="http://example.com/" property="homepage">Stephane
<p vocab="http://schema.org/" typeof="Person">
   My name is <a href="http://example.com/" property="homepage"
rel="me">Stephane Corlosquet</a>.

This issue has been discussed on the mailing list [3] and then during the
call on May 10th [4]. The following two options were discussed on the call:
1) If you have an element that has both @rel and @property in HTML5, then
the @rel can only take CURIEs, which will result in things like
rel="nofollow" being ignored
2) There is a more global one that in HTML5+RDFa a @rel value can only have

The following resolution was taken (essentially option 1):
"If @property and @rel/@rev are on the same elements, the non-CURIE and
non-URI @rel/@rev values are ignored. If, after this, the value of
@rel/@rev becomes empty, then the then the processor must act as if the
attribute is not present."

This resolution ensures that rel="license" on an element with no @property
is still supported.

Here is a quick survey of some authoritative sites which are using or
promoting rel="license". I found that very few are combining @property with
@rel in the same element, and when they do, they always use cc:license in
@rel. In other words, I could not find any example that would break with
the option choosen above. Here are the sources I looked at:

# No use of @property and @rel in the same element:
A random wikipedia page:
A random Flickr page: http://www.flickr.com/photos/60223652@N00/2677272571/

# Use of @property and @rel in the same element using CURIEs:

# Use of @property and rel="license":


[1] http://www.w3.org/TR/html5-author/links.html#linkTypes
[2] http://microformats.org/wiki/existing-rel-values
[3] http://www.w3.org/2010/02/rdfa/track/issues/135
Received on Thursday, 6 September 2012 06:32:52 UTC

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