- From: Mark Birbeck <mark.birbeck@webbackplane.com>
- Date: Sat, 14 Aug 2010 07:33:42 +0100
- To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
- Cc: public-rdfa-wg@w3.org
Hi Leif, This is an interesting problem. I agree that if @longdesc has a 'meaning' in HTML 5 then there should be a way to indicate what that meaning is so that an RDFa parser can pick it up. I don't think it would be good to put @longdesc into RDFa Core though, because ultimately we want to provide a framework for host language semantics, rather than providing those semantics ourselves. So, what might work is to: 1. Add a new concept to RDFa Core that defines mappings from an attribute name to a predicate (URI). These could be set by the host language in just the same that terms are. This list of mappings is then available to the parser and as traverses the tree it compares each attribute against this list. I don't see any reason why this list couldn't also be modified via profiles. (We'd also need to indicate in some way whether the attribute content is a URI or a literal, but I'm sure we can work that out.) 2. Create some template of words that could be added to a host language specification which makes it clear to implementers that some particular attribute requires mapping during RDFa processing. This latter is going to be tricky given that RDFa is not actually 'present' in HTML 5. But since other metadata solutions such as Microdata would probably also want to map @longdesc, then the host language merely needs to mention that @longdesc maps to a predicate with a URI of <x>, and leave it at that. Do you think that this would capture what you want to see? Regards, Mark -- Mark Birbeck, webBackplane mark.birbeck@webBackplane.com http://webBackplane.com/mark-birbeck webBackplane is a trading name of Backplane Ltd. (company number 05972288, registered office: 2nd Floor, 69/85 Tabernacle Street, London, EC2A 4RR) On Sat, Aug 14, 2010 at 3:58 AM, Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no> wrote: > There is a debate in the HTMLwg about the longdesc attribute. And in > that debate, the thought has surfaced that @longdesc, > > <img src="*" longdesc="long.html" alt="short description" /> > > is simply a *shorthand notation* for this (hypothetical) micro format > > <a href="long.html" rel="longdesc"> > <img src="*" alt="short description" /> > </a> > > This has resulted in an attempt to register the 'longdesc' as link > relation. [1] Simultaneously, a search for a better documentation of > implementations of @longdesc has been (re)started. And in that context, > I raised a question about RDFa and @longdesc. [2] > > Observation 1: The XHTML+RDFa DOCTYPE supports the @longdesc > attribute. > Observation 2: Mark Birbeck states in his 'Introduction to RDFa' > article that «The @rel and @href attributes are no longer confined to > the a and link elements, but can also be used on img to indicate a > relationship between the image and some other item.» [3] > Observation 3: A longdesc link indicates a relation between a short > description and a long description. (See the quotes from HTML4 provided > in [1]: 'link to long description (complements alt)' and 'link to long > description (complements title)'.) > > Questions: Would it not be logical if RDFa treated the @longdesc link > as a semantic link - e.g. equivalent to the micro format I described > above? What needs to be added in order to make this happen? > > [1] > http://www.ietf.org/mail-archive/web/link-relations/current/msg00047.html > [2] http://lists.w3.org/Archives/Public/public-html/2010Aug/0140 > [3] http://www.alistapart.com/articles/introduction-to-rdfa/ > -- > leif halvard silli > >
Received on Saturday, 14 August 2010 06:34:37 UTC