Re: The harm that can come if the W3C supports publication of competing specs

On Sun, 17 Jan 2010 20:47:29 +0100, Toby Inkster <> wrote:

> Cyclical references amongst blank nodes cannot be represented in
> Microdata. In Turtle an example might be:
>  @prefix foaf: <> .
>  _:bob foaf:knows _:jon .
>  _:jon foaf:knows _:bob .
> In RDFa it can be expressed quite simply:
>  <p xmlns:knows=""
>     about="_:jon" rel="knows:" rev="knows:" resource="_:bob">
>    Jon and Bob know each other.
>  </p>
> To express the same semantics in Microdata would require assigning a URI
> to at least one of the people. Certainly it's possible for a script to
> assign a URI on the fly, but committing to maintaining the meaning of
> that URI long-term is harder, which is why blank nodes are so frequently
> used in RDF.
> I believe, this could be addressed by allowing @itemid to contain a
> blank node name, and providing a way for @itemprop to specify a blank
> node as its value.

Right, if there's an actual need then it's easy to hardwire the _:foo  
syntax to create blank nodes in the RDF extraction algorithm. Currently  
the algorithm ignores item types which aren't absolute URIs. Is _:foo an  
absoute URI, or is it not a URI at all?

Philip Jägenstedt
Core Developer
Opera Software

Received on Monday, 18 January 2010 21:41:47 UTC