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Re: @itemid and URL properties in schema.org

From: Gregg Kellogg <gregg@kellogg-assoc.com>
Date: Sat, 5 Nov 2011 10:43:45 -0400
To: Jeni Tennison <jeni@jenitennison.com>
CC: Jason Douglas <jasondouglas@google.com>, "public-vocabs@w3.org" <public-vocabs@w3.org>, Guha <guha@google.com>, Dan Brickley <danbri@danbri.org>, HTML Data Task Force WG <public-html-data-tf@w3.org>
Message-ID: <3E2B5526-E4EC-4B0C-AAE1-0F1F8B9D3D0F@kellogg-assoc.com>
On Nov 4, 2011, at 2:17 PM, "Jeni Tennison" <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 that Thing/url is equivalent to itemid and either is accepted.
> 
> If 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?

I'll just note that this is a point that may require very special vocabulary-specific treatment in a processor generating RDF. Properties (@itemprop) create objects, not subjects. With some datatype information, such as we might include in a registry, we can know that a property using a literal value should be interpreted a URI reference. Assigning it as a subject is quite unnatural, as a BNode subject has already been created by the processor.

>>    • Add Thing/sameAs for stating item equivalences (via URLs) across data sources/sites.
> 
> Nice, I can see the potential for that :)

Alternatively, schema:url could be a subProperty of owl:sameAs, which after a fair amount of reasoning can yield what you want (in RDF that is). If schema:url really is used to designate the subject, much better to use @itemid in the first place.

Gregg

> I'd love to know whether there are any consumers of 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 markup with common @itemids or urls...
> 
> Jeni
> -- 
> Jeni Tennison
> http://www.jenitennison.com

> 
> 
Received on Saturday, 5 November 2011 14:44:20 GMT

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