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Empty @typeof...let's not lose this one again [was: two side issues on blank nodes...]

From: Mark Birbeck <mark.birbeck@webbackplane.com>
Date: Sat, 27 Mar 2010 12:44:58 +0000
Message-ID: <640dd5061003270544j6bfb3a41j8f01e9ea1ebaa88@mail.gmail.com>
To: Ivan Herman <ivan@w3.org>
Cc: W3C RDFa WG <public-rdfa-wg@w3.org>
Hi Ivan,

It's amazing that we've discussed empty @typeof so often, yet it still
doesn't seem to have become an erratum!

I was so convinced that we'd resolved this, that I went back through
the archives, and was surprised to discover that despite many
discussions, we never actually came up with an erratum.

(BTW, I'm not expecting anyone to read all of the following links, I'm
merely trying to make the case as strongly as I can that we've
discussed this many times, and so are fully aware of all the issues,
and therefore we should try to get a vote on this as soon as we can,
and hopefully be done with it once and for all.)


On Fri, Mar 26, 2010 at 4:24 PM, Ivan Herman <ivan@w3.org> wrote:
> While making an RDFa representation for the rdfa vocabulary the other
> day, I ran into two small issues for which I did not find an unambiguous
> answer or, if I believe it is unambiguous, I wonder whether we would not
> want to make slight changes.
>
> 1. Is the following 'legal'?
>
> <div typeof=""><span property="a:b">bla</span></div>
>
> Point 6 of the processing steps says: "If present, the attribute must
> contain one or more URIs,", so it is not legal. Ie, to create a new
> BNode one _has_ to use an explicit type to get something like
>
> [ rdf:type SOMETYPE;
>  a:b "bla" ]

This was first raised by Toby and Micah back in 2008:

  <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2008Sep/0020.html>

We seem to have discussed a related issue (raised by you and Ben), as
mentioned here:

  <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2008Sep/0023.html>

The related issue is that because parser writers are allowed to create
triples in other graphs, we have to be conscious of bnode alignment,
and the only way that we can ensure that alignment, is if the mere
*presence* of certain attributes triggers bnodes, independent of the
contents of the attribute. This applies to @rel, @rev and @typeof.

That same issue popped up again -- prompted by Jeni, this time -- in
the form of "what does it mean to 'ignore' an attribute":

  <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2009Sep/0085.html>

Once again we reply along the lines that @typeof needs to generate a
bnode, regardless of its content:

  <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2009Sep/0102.html>

I even proposed some wording for section 5.5.4...but again it slips
through the net.

Then on my part things get worse, because I actually raise this issue
with Manu as something we shouldn't forget:

  <http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2009Oct/0045.html>

but when I write up the proposal (URIs everywhere), I don't mention
empty @typeof.

Anyway, could we discuss this on the next call, and get it 'errated'?
It involves the removal of about 5 words, so really ought not to have
caused so much hassle.

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,
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Received on Saturday, 27 March 2010 12:45:34 GMT

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