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Re: schema.org Roles design

From: Dan Brickley <danbri@google.com>
Date: Wed, 26 Mar 2014 21:22:42 +0000
Message-ID: <CAK-qy=4hLOA9XRMip9P2C94yQRh9Yu-GMs68Z=FMvomsfR3hxg@mail.gmail.com>
To: Jarno van Driel <jarno@quantumspork.nl>
Cc: Jason Douglas <jasondouglas@google.com>, Guha <guha@google.com>, Gregg Kellogg <gregg@greggkellogg.net>, W3C Web Schemas Task Force <public-vocabs@w3.org>
On 26 March 2014 20:59, Jarno van Driel <jarno@quantumspork.nl> wrote:
> Well if @id has the same role as 'itemref' then could there also please be
> some info explaining how that works, because to be honest, I sort of
> understand the proposal but am confused about @id/itemid. e.g. to me it
> seems @id functions the same way as @resource does in RDFa, or at least
> that's how I read it.

The following are all similar in RDF-based languages - they identify
the entities being described:

RDF/XML: about= (for subjects, i.e. the thing that has the property),
resource= (for objects, i.e. a thing that is a value of some property)
RDFa 1.0: about= (for subjects), resource= (for objects),
http://www.w3.org/TR/2008/REC-rdfa-syntax-20081014/#rdfa-attributes
RDFa 1.1: about= (for subjects), resource= (for objects),
http://www.w3.org/TR/rdfa-syntax/#A-about
http://www.w3.org/TR/rdfa-syntax/#A-resource
RDFa 1.1 Lite ... doesn't make this distinction; resource= works for
either . http://www.w3.org/TR/rdfa-lite/#resource
JSON-LD: @id http://www.w3.org/TR/json-ld/#node-identifiers
Microdata: itemid=
http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#global-identifiers-for-items

Most of these also have a way of using less-than-global local
identifiers too, as a way of joining up a graph structure from
different trees of markup. Microdata's itemref can also sometimes be
used for that purpose but as already discussed it is a different kind
of mechanism.

> Wouldn't the Person linking back to the AmericanFootballRole create an infinite loop?

This is no more problematic than someone being their mother's son.
These languages are all oriented towards describing relationships; it
is natural that sometimes there will be loops.

Dan
Received on Wednesday, 26 March 2014 21:23:10 UTC

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