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Re: @itemid and URL properties in schema.org

From: Adrian Giurca <giurca@tu-cottbus.de>
Date: Sat, 05 Nov 2011 09:08:36 +0100
Message-ID: <4EB4EF04.5000204@tu-cottbus.de>
To: Jason Douglas <jasondouglas@google.com>, Jeni Tennison <jeni@jenitennison.com>
CC: public-vocabs@w3.org, Guha <guha@google.com>, Dan Brickley <danbri@danbri.org>, HTML Data Task Force WG <public-html-data-tf@w3.org>
Dear Jeni, Jason and all,
Thank you for this useful thread that give some answers to my previous 
It is schema.org choice to use url (property of Thing) as a reference 
mechanism to other objects. I understand that "url" was preferred to 
"itemid" because of better understanding of the users and easy reusing 
of the value.

I would also conclude that while http://schema.org defines the 
vocabulary, its extensions principles, and offers examples on how to use 
it with microdata annotations, it does not explain how a schema.org 
processor will handle these annotations.

Therefore, I would say that *there is no fixed semantics of schema.org* 
and this was required from the beginning of the initiative.
In addition, looks like the OWL ontology 
<http://schema.org/docs/schemaorg.owl>representation of schema.org does 
not sync completely because of some major differences such as
the ones explained by Peter  Mika's email 
<http://lists.w3.org/Archives/Public/public-vocabs/2011Nov/0024.html> to 
this thread and probably others.

As a continuous learner I will come back with new questions soon.

-Adrian Giurca

On 11/4/2011 10:40 PM, Jason Douglas wrote:
> On Fri, Nov 4, 2011 at 2:17 PM, Jeni Tennison <jeni@jenitennison.com 
> <mailto:jeni@jenitennison.com>> wrote:
>     Jason,
>     That's *really* helpful, thank you, especially around the
>     rationale for the 'url' property.
>     You suggest:
>     On 4 Nov 2011, at 19:31, Jason Douglas wrote:
>     > So to throw a strawman out there, maybe we could:
>     >        State on schema.org <http://schema.org> that Thing/url
>     is equivalent to itemid and either is accepted.
>     If schema.org <http://schema.org> does this, it should also state
>     what happens when both are specified and they clash. Perhaps they
>     should be treated as aliases with the @itemid being the canonical URL?
> Yeah, that sounds right to me.
>     >        Add Thing/sameAs for stating item equivalences (via
>     URLs) across data sources/sites.
>     Nice, I can see the potential for that :)
>     I'd love to know whether there are any consumers of schema.org
>     <http://schema.org> markup that are or plan to aggregate data
>     across different sites to create a view of information about the
>     same thing, and indeed whether there are any publishers who are
>     generating schema.org <http://schema.org> markup with common
>     @itemids or urls...
> My day job is Freebase and url mappings to entities (and therefore to 
> each other) has always been one of the most useful features of that 
> dataset for developers.  I'd love to see that happen on a much bigger 
> scale...
> -jason
>     Jeni
>     --
>     Jeni Tennison
>     http://www.jenitennison.com
Received on Saturday, 5 November 2011 08:09:25 UTC

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