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 <http://www.w3.org/2011/rdfa-context/xhtml-rdfa-1.1> [2] http://www.w3.org/TR/html5/links.html#linkTypes <http://www.w3.org/TR/html5/links.html#linkTypes> [3] http://www.w3.org/TR/2015/REC-html-rdfa-20150317/ <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
Received on Thursday, 19 November 2015 15:40:38 UTC