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Re: longdesc URLs and RDFa

From: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Date: Sat, 14 Aug 2010 14:26:05 +0200
To: Mark Birbeck <mark.birbeck@webbackplane.com>
Cc: public-rdfa-wg@w3.org
Message-ID: <20100814142605711656.280896be@xn--mlform-iua.no>
Hi Mark,

Mark Birbeck, Sat, 14 Aug 2010 07:33:42 +0100:
> This is an interesting problem.
> I agree that if @longdesc has a 'meaning' in HTML 5 

I don't believe it has "more" meaning in HTML5 than in HTML4 and XHTML. 
(At the moment, @longdesc is not permitted in HTML5 - but that is 
another, though not unrelated problem.) It is best, I think, to focus 
on HTML and XHTML in a "universal" way, I think.

> 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.

Modification via profiles sounds meaningful.

> (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.

I'm not certain what you mean by "present". Could it not be made clear 
to implementors via the HTML+RDFa specification?

> 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?

Probably. :-)

But do you have one or two small examples that show how it could be 
done? For example, does the solution(s) you suggest require that one 
also add @rel, @resource and @content to the <img> - as explained by 
Ivan? And are  1. (profile etc) and 2. (template etc) two different 
ways to achieve the goal, or are both 1. and 2. required to make it 
leif halvard silli
Received on Saturday, 14 August 2010 12:26:39 UTC

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