W3C home > Mailing lists > Public > www-tag@w3.org > July 2011

Re: Dropping RDF mapping from microdata spec

From: Richard Cyganiak <richard.cyganiak@deri.org>
Date: Thu, 28 Jul 2011 14:01:06 +0100
Cc: Michael Hausenblas <michael.hausenblas@deri.org>, "www-tag@w3.org List" <www-tag@w3.org>
Message-Id: <EBFD87F4-D0F8-45C2-820D-F927BCE203BB@deri.org>
To: Jeni Tennison <jeni@jenitennison.com>
Hi Jeni,

(I stumbled into the middle of this thread, so apologies if I'm out of context)

On 27 Jul 2011, at 22:25, Jeni Tennison wrote:
> From what I can see, the documented meaning of http://schema.org/startDate and http://schema.org/endDate is different depending on whether the item is a TVSeason/TVSeries or an Event.

What makes you think so? The documentation (in the table of properties) is exactly the same.

> IIRC, one reason that Hixie gives for the complexity of the generated property URIs in the current microdata/RDF mapping is to ensure that properties with potentially different semantics (that appear on items of different types) have distinct URIs. But of course when you have inheritance in a vocabulary like schema.org, you don't want distinct URIs by type.


> Makes me think you can't have a generic mapping that gives a good output in RDF terms.

My conclusion too.

The Microdata spec gives certain powers to the documents that define vocabularies. Does the vocabulary allow dereferencing of type URLs? Which types support itemid? That's up to the document defining the vocabulary.

I was thinking that the Microdata spec could say that these documents can also specify how local property names are expanded to IRIs in the RDF mapping. So, the schema.org documentation could authoritatively define that startDate gets expanded to http://schema.org/startDate or whatever else makes sense.

That would of course be moot if the RDF mapping gets dropped.

Received on Thursday, 28 July 2011 13:01:48 UTC

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