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

From: Jarno van Driel <jarnovandriel@gmail.com>
Date: Mon, 2 Jun 2014 21:20:15 +0200
Message-ID: <CADK2AU09xiE+aFFLNHqU6ZwJVwrNU5qYWs2hq7hZj_-mtCBY2g@mail.gmail.com>
To: Dan Brickley <danbri@google.com>
Cc: Dan Scott <dan@coffeecode.net>, Jocelyn Fournier <jocelyn.fournier@gmail.com>, W3C Web Schemas Task Force <public-vocabs@w3.org>
Besides the naming of the property I was wondering what to do when the main
entity isn't a single thing but a collection of things. For example a
category page (CollectionPage) of an eCommerce site which shows a
collection of products?

In this case there is no main entity unless it's the predicate for a
Collection entity. (Maybe something as described in the Collection proposal
- http://www.w3.org/wiki/WebSchemas/Collection).

When I combine the 2 I can imagine marking up something like this:

<body vocab="http://schema.org/" typeof="CollectionPage">
  <header property="hasPart" typeof="WPHeader">...</header>

  <main property="mainEntity" typeof="Collection">
      <li property="hasPart" typeof="Product">...</li>
      <li property="hasPart" typeof="Product">...</li>

  <aside property="hasPart" typeof="WPSideBar">...</aside>

Or would it be OK to add a property like @mainEntity first and work on the
collection issue separately?

*Jarno van Driel*
Technical & Semantic SEO Consultant
8 Digits - Digital Marketing Technologies

2014-05-21 22:59 GMT+02:00 Jarno van Driel <jarnovandriel@gmail.com>:

> What I think we want is a property that performs the same role as FOAF's
>> 'primaryTopic': it should point to at most one entity/thing. Given
>> currently popular terminology we might call it 'mainEntity' as a
>> strawman.
> Couldn't changing the expected value of @mainContantOfPage to Thing work
> for this?
> Doing so would actually help a lot of websites. I've lost count how many
> times I've encountered:
> <div itemprop="mainContentOfPage" itemscope itemtype="
> http://schema.org/Product"> (or Article or Blog).
> And by expanding the domain of @mainContentOfPage all those websites would
> automagically have valid markup.
> 2014-05-21 21:22 GMT+02:00 Dan Brickley <danbri@google.com>:
> On 21 May 2014 19:21, Dan Scott <dan@coffeecode.net> wrote:
>> > 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?
>> That's the right question to be asking. And I didn't ask it hard
>> enough yesterday (probably because I wouldn't have liked the answer).
>> The wording http://schema.org/about has currently, "The subject matter
>> of the content." is awkward. The word "the" suggests a single thing is
>> the subject matter, but it is vague enough that you could have several
>> entities via repeated properties together capturing "the subject
>> matter".
>> What I think we want is a property that performs the same role as
>> FOAF's 'primaryTopic': it should point to at most one entity/thing.
>> Given currently popular terminology we might call it 'mainEntity' as a
>> strawman.
>> I was hoping we could get away with refining the interpretation of
>> 'about', but I'm coming around to the view that it has been used in
>> too many diverse ways over the last 3 years for that to work.
>> >> 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 don't think they're great examples of about-ness, except
>> ContactPoint, if the page is indeed about contact info. The
>> stereotypical use for 'about' is a specific person-place-or-thing that
>> the content is 'about'. Sidebars and lists are structural mechanisms;
>> it would be more typical to see Product, Book, Person, Place etc used.
>> However your main point, that 'about' could credibly be repeated given
>> its definition, is quite reasonable.
>> >
>> > 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.
>> Yeah. It is tempting to defend a strict reading of the word 'the' and
>> claim it shouldn't _really_ be repeated; but I don't think that's
>> credible.
>> > 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.
>> quite :)
>> > 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.
>> There are a few (e.g. birthDate, deathDate, most boolean-valued
>> properties) that have at most one sensible value. However even those
>> might have several reasonable encodings. And there are some, e.g.
>> iataCode hopefully, for which there should be at most one entity that
>> has any given value for that property. However we've not attempted
>> cataloguing these cases, partly through a concern to avoid making
>> unrealistically brittle and rigid rules that will be ignored...
>> cheers,
>> Dan
Received on Monday, 2 June 2014 19:20:43 UTC

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