ISSUE-5: Determining intended cardinality of schema.org properties

property cardinality

Determining intended cardinality of schema.org properties

State:
CLOSED
Product:
Feedback on Schema.org
Raised by:
Philip Jägenstedt
Opened on:
2011-10-21
Description:
Via John Panzer and Philip Jägenstedt in http://lists.w3.org/Archives/Public/public-vocabs/2011Oct/0077.html

"""On Thu, 20 Oct 2011 01:22:02 +0200, John Panzer <jpanzer@google.com> wrote:

> I'm trying to determine how to know what the intended cardinality of any
> given schema.org defined property.

I asked about this and got this answer: [1]

On Thu, Jun 16, 2011 at 06:56, Guha <guha@google.com> wrote:

> Right now, it is always allowed to have multiple values.
> In the future, we could/should introduce a property of properties that
> specifies when a property may have only a single value.

Not exactly a satisfactory situation, but there it is.

[1]
http://groups.google.com/group/schemaorg-discussion/browse_thread/thread/95dfc4aa1ab89dbf?pli=1

--
Philip Jägenstedt
Core Developer
Opera Software"""
Related Actions Items:
No related actions
Related emails:
  1. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from jarnovandriel@gmail.com on 2014-08-06)
  2. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from martin.hepp@ebusiness-unibw.org on 2014-08-06)
  3. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from jarnovandriel@gmail.com on 2014-08-05)
  4. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from jarnovandriel@gmail.com on 2014-06-02)
  5. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from jarnovandriel@gmail.com on 2014-05-21)
  6. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from danbri@google.com on 2014-05-21)
  7. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from jarnovandriel@gmail.com on 2014-05-21)
  8. Re: Indicating main entity / primaryTopic - proposal to use 'schema.org/about' (from dan@coffeecode.net on 2014-05-21)
  9. Re: Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from danbri@danbri.org on 2012-03-09)
  10. Re: Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from will@willnorris.com on 2012-03-01)
  11. Re: Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from phil.barker@hw.ac.uk on 2012-03-01)
  12. Re: Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from scorlosquet@gmail.com on 2012-03-01)
  13. Re: Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from danbri@danbri.org on 2012-03-01)
  14. Re: Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from giurca@tu-cottbus.de on 2012-02-28)
  15. Schema.org property cardinality and use of plural (WAS Re: SoftwareApplication proposal for schema.org) (from lin.w.clark@gmail.com on 2012-02-24)
  16. Re: Comment versus UserComments (from giurca@tu-cottbus.de on 2012-01-19)
  17. Re: Comment versus UserComments (from daniel@google.com on 2012-01-18)
  18. Re: Comment versus UserComments (from danbri@danbri.org on 2012-01-18)
  19. Re: Cardinality of schema.org properties (ISSUE-5) (from martin.hepp@ebusiness-unibw.org on 2011-10-25)
  20. Re: Cardinality of schema.org properties (ISSUE-5) (from gregg@kellogg-assoc.com on 2011-10-21)
  21. Re: Cardinality of schema.org properties (from danbri@danbri.org on 2011-10-21)
  22. webschema-ISSUE-5 (property cardinality): Determining intended cardinality of schema.org properties [Feedback on Schema.org] (from sysbot+tracker@w3.org on 2011-10-21)

Related notes:

Lin Clark in http://lists.w3.org/Archives/Public/public-vocabs/2011Oct/0089.html adds

"""I have to say, I think this is going to be really confusing as time goes on.

For example, Schema.org already defines a 'video' term for CreativeWork. However, Google's Software Application itemtype introduces a 'videos' term, presumably because they want to indicate that an app can have multiple videos. This means that the Software Application has both a 'video' property and a 'videos' property.

Also, for a property such as 'videos', which takes an item as it's value, the itemprop attribute must be placed on the singular... on the div that defines that singular item. I think it's a little strange to have a plural property on a singular and will probably lead publishers to use microdata as they would RDFa... in fact, this already happens in a Goodreads snippet that Jayson Lorenzen posted on the HTML data TF list:

<div class="infoBoxRowItem" itemprop='awards'>
<a href="/award/show/9-hugo-award" class="award">Hugo Award for Best Novel (1985)</a>, <a href="/award/show/23-nebula-award" class="award">Nebula Award for Best Novel (1984)</a>, <a href="/award/show/326-philip-k-dick-award" class="award">Philip K. Dick Award (1984)</a>, <a href="/award/show/1403-john-w-campbell-memorial-award" class="award">John W. Campbell Memorial Award Nominee for Best Science Fiction Novel (1985)</a>
</div>

The awards should be placed on each individual link, not the wrapping div. However, I can't blame the Goodreads developer for not understanding that.

My opinion is that terms should be singular. This communicates much more clearly how they should be used in microdata... if it's a choice between having data that can't be properly parsed or having data that breaks implicit cardinality rules, I would take the later."""

Dan Brickley, 21 Oct 2011, 12:00:59

Aside: note that Schema.org's class naming re plurals ("User Interaction*s*) is also somewhat unconventional; we should probably track that issue here or separately, yet deal with the issue in a unified way.

Dan Brickley, 18 Jan 2012, 19:19:21

See also list from Lin, collecting (all?) the plural-named properties, http://lists.w3.org/Archives/Public/public-vocabs/2012Feb/0098.html

I'd like to see singular aliases for these; expressing cardinality through property plurality isn't working well in markup.

Dan Brickley, 27 Feb 2012, 17:18:42

http://www.w3.org/wiki/WebSchemas/Singularity has a proposal partially addressing this.

Dan Brickley, 2 Mar 2012, 15:14:48

Resolved 2012-03-09 that we will no longer express cardinality / repeatability of properties using plural spellings.

Full details are in the Wiki, http://www.w3.org/wiki/WebSchemas/Singularity

Dan Brickley, 9 Mar 2012, 20:30:08

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