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Re: Multiple itemtypes in microdata

From: Jeni Tennison <jeni@jenitennison.com>
Date: Sun, 16 Oct 2011 12:55:09 +0100
Cc: public-html-data-tf@w3.org
Message-Id: <7CCBB425-750C-4663-9E1D-8FEAC5D97754@jenitennison.com>
To: Ian Hickson <ian@hixie.ch>

On 12 Oct 2011, at 23:30, Ian Hickson wrote:
> On Wed, 12 Oct 2011, Jeni Tennison wrote:
>> If support for multiple types from different vocabularies is definitely 
>> out of scope for microdata, it would be really helpful to understand the 
>> rationale so that we can document it for users.
> 
> Nobody has asked for it in an actionable manner (giving concrete use cases 
> that demonstrate real need, e.g. showing real Web pages where there really 
> are two incompatible vocabularies that are nonetheless compatible enough 
> that it actually makes sense to have some sort of special syntax for 
> mixing the vocabularies).


Here are some web pages that currently include multiple types using RDFa (thanks to Martin for the pointer to sears.com):

= examiner.com =

Example: http://www.examiner.com/fall-colors-in-national

Each article on the site is marked up as being:
  * http://schema.org/NewsArticle 
  * http://rdfs.org/sioc/ns#Item 
  * http://xmlns.com/foaf/0.1/Document

In this case, the three types are progressively more specific descriptions of the article.


= sears.com =

Example: http://www.sears.com/shc/s/p_10153_12605_04450094000P

Each item for sale is marked up as being:
  * http://purl.org/goodrelations/v1#SomeItems 
  * a type from the http://www.productontology.org/id/ vocabulary, in the example http://www.productontology.org/id/Earrings

Again, the product ontology type is more specific than the GoodRelations type. I imagine they might add http://schema.org/Product as a type at some point in the future.


= digifotopro.nl =

Example: http://www.digifotopro.nl/

The footer on each page describes some organisations, each of which is marked as being:
  * http://xmlns.com/foaf/0.1/Organization
  * http://rdf.data-vocabulary.org/#Organization

Here, there are two vocabularies with types that mean exactly the same thing, but neither has clear universal adoption and the publisher is hedging their bets by labelling each organisation with both types. I imagine they'll add http://schema.org/Organization as well when they get round to updating their site.


There are dedicated consumers for some of these vocabularies -- in particular the schema.org and data-vocabulary.org vocabularies are used for rich snippets in search engines. But there are also generic consumers of the data which use the types to aid people's searches. For instance, Sindice [1] enables you to search for pages that contain information about things of particular types. For example, you can search for foaf:Documents on "HTML5":

  http://sindice.com/search?q=HTML5&nq=&fq=class%3Afoaf%3ADocument

or schema:NewsArticles on "HTML5":

  http://sindice.com/search?q=HTML5&nq=&fq=class%3Ahttp%3A%2F%2Fschema.org%2FNewsArticle
  

Hope this helps. Let me know if you need anything more.

Cheers,

Jeni

[1] http://sindice.com/
-- 
Jeni Tennison
http://www.jenitennison.com
Received on Sunday, 16 October 2011 11:55:47 GMT

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