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Re: A Proposal for subject setting by @class

From: Mark Birbeck <mark.birbeck@x-port.net>
Date: Tue, 10 Jul 2007 12:24:24 +0100
Message-ID: <640dd5060707100424h2f03d20anca64f161c9e5d32d@mail.gmail.com>
To: "Ben Adida" <ben@adida.net>
Cc: RDFa <public-rdf-in-xhtml-tf@w3.org>

Hi Ben,

> I propose that, when a @class appears with a namespaced-value, there be
> an implicit @about set for contained statements, exactly as if there
> were a @rel. I suspect someone else has brought this up before, but I
> can't seem to find it in the archive.
>
> [snip]
>
> This is a small but noticeable change, and it may invalidate some
> existing markup (though unlikely, since most use case here involve using
> an @about on the same @div, in which case the @about takes precedence.)

I think there has been strong support for exactly your proposed
syntax, and I think you are right that there would be no side-effects
with adopting it.

In the past we have said that @class is a shorthand for a <link> with
@rel="rdf:type". In other words this:

  <div class="cal:Vevent">
    <span property="cal:dtstart">2007-07-07</span>
  </div>

is a shorthand for this:

  <div>
    <link rel="rdf:type" href="[cal:Vevent]" />
    <span property="cal:dtstart">2007-07-07</span>
  </div>

We've always said that the 'nested' <link> has the effect of creating
a bnode based on the <div>, and it's only recently that we've had to
drop this support. So I think that 'conceptually' the model of @class
adding an rdf:type predicate, and simultaneously creating a bnode if
there is no subject--which is what your requirement amounts to--is
there in RDFa, and I would say that you are perfectly justified in
seeking to make this more explicit.

(I would add though, that this seems to me to be further justification
for using a different attribute for rdf:type; when reading a document
it would be quite easy to not notice that your <div> has a bnode if we
were relying on @class as the indicator.)

Regards,

Mark

-- 
  Mark Birbeck, formsPlayer

  mark.birbeck@x-port.net | +44 (0) 20 7689 9232
  http://www.formsPlayer.com | http://internet-apps.blogspot.com

  standards. innovation.
Received on Tuesday, 10 July 2007 11:24:28 GMT

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