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

From: Jarno van Driel <jarnovandriel@gmail.com>
Date: Tue, 5 Aug 2014 22:52:30 +0200
Message-ID: <CADK2AU0yhGbkhRc8fHP+ggfkmsshAt70oZvjJTwcBRKm8=45mQ@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>
To revive the subject of this thread I have made some markup examples
(microdata).

The first example illustrates what could happen if we add a new property
like 'mainEntity' as opposed to expanding the range of 'mainContentOfPage'
to Thing:

https://www.w3.org/wiki/WebSchemas/ChainingLayoutElements#A_CollectionPage_which_has_an_ItemList_as_it.27s_mainEntity_.28down_the_DOM.2C_normal_relation.29_2

While the next two examples illustrate, that if the markup is less
elaborate, explaining the difference when to use mainContentOfPage or
mainEntity start to become difficult:

https://www.w3.org/wiki/WebSchemas/ChainingLayoutElements#A_CollectionPage_which_has_an_ItemList_as_it.27s_mainContentOfPage_.28down_the_DOM.2C_normal_relation.29

https://www.w3.org/wiki/WebSchemas/ChainingLayoutElements#A_CollectionPage_which_has_an_ItemList_as_it.27s_mainEntity_.28down_the_DOM.2C_normal_relation.29

Yet if we expand the range of 'mainContentOfPage' to Thing we could get
something like this:
https://www.w3.org/wiki/WebSchemas/ChainingLayoutElements#CollectionPage.2C_ItemList.2C_Product

Looking at this I think I'd prefer to expand the range of
'mainContentOfPage' to Thing as opposed to adding 'mainEntity'. Solely
because a lot less markup is needed.

Any thoughts?




2014-06-02 21:20 GMT+02:00 Jarno van Driel <jarnovandriel@gmail.com>:

> 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">
>     <ul>
>       <li property="hasPart" typeof="Product">...</li>
>       <li property="hasPart" typeof="Product">...</li>
>       ...
>     </ul>
>   </main>
>
>   <aside property="hasPart" typeof="WPSideBar">...</aside>
> </body>
>
> 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 Tuesday, 5 August 2014 20:52:58 UTC

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