- From: Mark Birbeck <mark.birbeck@webbackplane.com>
- Date: Sun, 7 Sep 2008 20:48:33 +0100
- To: "Micah Dubinko" <Micah.Dubinko@marklogic.com>
- Cc: "Toby A Inkster" <tai@g5n.co.uk>, RDFa <public-rdf-in-xhtml-tf@w3.org>
Hi Micah/Toby, I haven't had chance to check the wording, but Micah is right. :) A similar issue came up in relation to @rel and @rev (spotted by Ben and Ivan, I believe), which we fixed. It's a shame that we didn't spot the related @typeof issue at the same time. Anyway, the core idea is that there are a number of different ways that you might end up with an 'empty' value, not just one that is literally empty. For example, if you have @typeof="foo", and "foo" is not a known token, then the default graph will contain no representation of the type of the bnode. To all intents and purposes, the @typeof is 'empty'. But since the specification allows other graphs to be created, there may be some other graph that contains: _:bnode a <whatever foo is> . So if we want to tie two graphs together, we need to know the bonde value. This means that when we see a @typeof we need to create the bnode, regardless of whether the @typeof itself contains anything for our graph, because we cannot tell the difference when parsing between this: typeof="" and this: typeof="notforus" I.e., we need to unconditionally create the bnode. Regards, Mark On Sun, Sep 7, 2008 at 6:36 PM, Micah Dubinko <Micah.Dubinko@marklogic.com> wrote: > > This is an interesting case. > > My impl produces this: > > _:bnode dc:title "xyzzy" > > Which I think might actually be right. > > The mere presence of @typeof triggers creating a new bnode. > But since it doesn't have a valid CURIE, there is no generated triple with > rdf:type. > > Agree that a minor editorial clarification would be nice. > > -m > > > On 9/7/08 2:30 AM, "Toby A Inkster" <tai@g5n.co.uk> wrote: > >> >> What is the meaning of this? >> >> <div about="#foo"> >> <div typeof=""> >> <span property="dc:title">xyzzy</span> >> </div> >> </div> >> >> Is "xyzzy" the title of "#foo" or the title of a BNode created by the >> second <div>? >> >> Step #4 and #5 in the processing sequence say "if @typeof is present" >> then typeof sets a new subject. However, step #6 says of @typeof: "if >> present, the attribute must contain one or more URIs" (i.e. not zero >> or more). >> >> Can an empty typeof set a new subject, or is it invalid and thus >> ignored? It would be nice if the syntax document could be clarified. >> >> Yes, I know it would be helpful if I'd raised this issue before RDFa >> reached PR stage, but I've only just noticed it. > > > -- 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)
Received on Sunday, 7 September 2008 19:49:12 UTC