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Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about'

From: Jarno van Driel <jarnovandriel@gmail.com>
Date: Wed, 21 May 2014 20:42:11 +0200
Message-ID: <CADK2AU2beY09gr2C1k-0UUqbADSp_ujFqRFDVH18quL8-B2eRw@mail.gmail.com>
To: Dan Scott <dan@coffeecode.net>
Cc: Jocelyn Fournier <jocelyn.fournier@gmail.com>, Dan Brickley <danbri@google.com>, W3C Web Schemas Task Force <public-vocabs@w3.org>
> "I'm not going to offer any advice about whether "hasPart" or "mentions"

Of course any statement about this depends depends greatly on whether or
not the Periodicals proposal gets accepted or not (which I'm all for by the

And I'm aware properties can be declared multiple times (which could use
some more attention indeed) but looking at the topic: 'indicating main
entity', having multiple of those seems a bit odd.

The HTML5 <main> tag for example is the only HTML tag that should be used
only once. And maybe the property for expressing the 'main entity' should
go this way as well. Because if not, than how can an entity be the main
entity if the property indicating this can be used multiple times?

And what about expressing the main entity on a CollectionPage?
Should this specify: @about > Collection? If so, then this proposal should
get accepted as well or specifying a single main entity will be quite

And I'm not fixed on any of this per se. I just thought I'd throw it into
the group to find out how others look at this and if there are any
philosophical or technical reasons why there shouldn't/can't be a single

2014-05-21 20:21 GMT+02:00 Dan Scott <dan@coffeecode.net>:

> On Wed, May 21, 2014 at 02:04:20PM +0200, Jarno van Driel wrote:
>> I was wondering, can an entity also have multiple @about properties?
>> I ask because when chaining multiple entities to a WebPageElement, to me
>> it
>> seems the following is the logical thing to do:
>> <body itemscope itemtype="http://schema.org/WebPage">
>>    ...
>>    <div itemprop="hasPart" itemscope itemtype="http://schema.org/
>> WPSideBar">
>>        <div itemprop="about" itemscope itemtype="http://schema.org/
>> ContactPoint">...</div>
>>        <div itemprop="about" itemscope itemtype="http://schema.org/
>> ItemList">...</div>
>>    </div>
>>    ...
>> </body>
>> Or would @hasPart or @mentions be prefered over @about?
> I'm not going to offer any advice about whether "hasPart" or "mentions"
> might be preferred here, but you can certainly have multiple "about"
> properties for a single entity.
> See the example for http://schema.org/MedicalScholarlyArticle - "about"
> is used twice, because the article is about a type of drug and
> about a type of medical condition.
> The cardinality of schema.org properties appears to be a FAQ dating back
> to at least 2011 (http://www.w3.org/2011/webschema/track/issues/5); we
> should probably add an explicit statement to
> http://schema.org/docs/gs.html or http://schema.org/docs/faq.html (or
> both) saying that you can, in general, repeat properties in schema.org
> entities as necessary.
Received on Wednesday, 21 May 2014 18:42:40 UTC

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