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Property singular vs. plural usage and impact on validators

From: Aaron Bradley <aaranged@yahoo.com>
Date: Mon, 30 Apr 2012 17:51:17 -0700 (PDT)
Message-ID: <1335833477.26522.YahooMailNeo@web161006.mail.bf1.yahoo.com>
To: Public Vocabs <public-vocabs@w3.org>
As followers of this list know well, there has been much discussion of (to borrow from the main thread title on this) "property cardinality and use of plural".

The proposal for dealing with this has been accepted [1], and the action issues related to this [2],[3] have been closed.

All fine and well.  The decision has been made, and pages that list post singular and plural forms of the same property have notations explaining the difference, such as one finds on MusicEvent [4]:

A person or organization attending the event.

A person attending the event (legacy spelling; see singular form, attendee).

Again, all fine and well.  In this case the plural is the legacy form, and I should be using the singular form.

But if I run this code through the Rich Snippets Testing Tool [5]:

<div itemscope itemtype="http://schema.org/MusicEvent">
    <div itemprop="name">Lady Gaga in Concert</div>
    <div itemprop="location">Wells Fargo Center</div>
    <div itemprop="performer">Lady Gaga</div>
    <div itemprop="performers">Lady Gaga</div>
    <div itemprop="attendee">Rabid Fan</div>
    <div itemprop="attendees">Rabid Fan</div>
    <div itemprop="subEvent">An Intimate Jam with Lady Gaga</div>
    <div itemprop="subEvents">An Intimate Jam with Lady Gaga</div>
    <div itemprop="superEvent">Great Women of Rock</div>
    <div itemprop="superEvents">Great Women of Rock</div>
    <meta itemprop="startDate" content="2016-04-21T20:00">Thu, 04/21/16 8:00 p.m.

I get these warnings:
Warning: Page contains property "performer" which is not part of the schema.
Warning: Page contains property "attendee" which is not part of the schema.
Warning: Page contains property "subevent" which is not part of the schema.
Warning: Page contains property "superevents" which is not part of the schema.

And similar warnings from the linter [6]:

property schema:performer: No property definition found
property schema:subEvent: No property definition found
property schema:superEvents: No property definition found
property schema:attendee: No property definition found

The only one of these warnings that make sense is for "superevents" as it is not listed in the schema.

But if someone could please verify that:
(1) The singular forms "performer", "attendee" and "event" are valid.

(2) The singular forms "performer", "attendee" and "event" are in fact preferred.

As usual, folks, I stand as your surrogate everyday webmaster here.  And in that capacity I just spent more time than I care to confess trying to figure out what was wrong with my syntax in using "performer".  Apparently nothing, right?  But that's not what the testing tool most commonly used by webmasters told me.

Aside from double checking that I've got this right, a suggested action item, if I may?  Don't publish properties to the schema.org site that result in validation errors on Google's Rich Snippet Testing Tool, or at least warn webmasters that they won't validate.

Oh, I tested this in Bing WMT as well - it simply did not the properties that the RSTT listed as not being part of the schema:

    Type: http://schema.org/MusicEvent
    name: Lady Gaga in Concert
    location: Wells Fargo Center
    performers: Lady Gaga
    attendees: Rabid Fan
    subEvents: An Intimate Jam with Lady Gaga
    superEvent: Great Women of Rock
    startDate: 2016-04-21T20:00

Aaron Bradley

[1] http://www.w3.org/wiki/WebSchemas/Singularity
[2] https://www.w3.org/2011/webschema/track/actions/4
[3] http://www.w3.org/2011/webschema/track/issues/5
[4] http://schema.org/MusicEvent
[5] http://www.google.com/webmasters/tools/richsnippets
[6] http://linter.structured-data.org/
Received on Tuesday, 1 May 2012 00:51:46 UTC

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