Re: Usage of @rel in RDFa with @vocab: is it a bug? Should it be a bug?

I don't feel this is a bug at all.  It is as designed.  In fact, the whole
thing with @vocab was to permit the dpub (daisy and others) community to
switch into their own vocabulary so they would not need to prefix their
terms.  I don't see how we could back away from that at this late date.

On Thu, Nov 19, 2015 at 9:40 AM, Ivan Herman <ivan@w3.org> wrote:

> Dear all,
>
> some of us have had discussions these days with different groups on the
> usage of @rel and the way it is handled in RDFa1.1. The current situation
> is as follows:
>
> 1. CURIE values of @rel are treated to generate RDF properties (although,
> in RDFa Lite, @property can mostly replace @rel)
> 2. By default, *terms* (ie, just strings and not CURIEs) are mostly
> ignored, except for the three terms defined in the initial context of
> RDFa[1]
> 3. However, if a @vocab is used somewhere in the hierarchy, then the terms
> in @rel are used as being part of that vocabulary.
>
> The range of acceptable values for @rel, in HTML5, is defined, on the one
> hand, by the HTML5 standard[2] but there is also the possibility for the
> community to add new values via the relevant microformat wiki page. (The
> discussion, actually, that I refer to above is around possibly new @rel
> value in the accessibility space.) s long as we are not in situation #3
> above all is fine: users may use those values and they will be ignored by
> RDFa. However: if a @vocab is used, then these two usages may clash: the
> term value in @rel will be picked up and will be used to generate possibly
> completely rubbish triples.
>
> I wonder how to handle that. It does feel like a bug to me. However, the
> usage of @rel is fairly deeply built into RDFa core, so if we disallow the
> usage of @vocab for @rel overall, it pretty much makes @vocab useless. An
> alternative would be to extend the HTML+RDFa spec[3] with an additional
> restriction whereby if the @rel value appears on a <a> or a <link> elements
> (the two elements on which vanilla HTML5 allows @rel) then rule #3 is
> disallowed.
>
> At this point it would be fairly difficult to do anything else than
> declare this as a bug and add this to the errate. But maybe some of you
> have some a much better idea on how to handle this…
>
> Cheers
>
> Ivan
>
>
>
> [1] http://www.w3.org/2011/rdfa-context/xhtml-rdfa-1.1
> [2] http://www.w3.org/TR/html5/links.html#linkTypes
> [3] http://www.w3.org/TR/2015/REC-html-rdfa-20150317/
>
>
>
> ----
> Ivan Herman, W3C
> Digital Publishing Lead
> Home: http://www.w3.org/People/Ivan/
> mobile: +31-641044153
> ORCID ID: http://orcid.org/0000-0003-0782-2704
>
>
>
>
>


-- 
Shane McCarron
Managing Director, Applied Testing and Technology, Inc.