Re: longdesc URLs and RDFa

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 
work? 
-- 
leif halvard silli

Received on Saturday, 14 August 2010 12:26:39 UTC