W3C home > Mailing lists > Public > public-vocabs@w3.org > September 2012

Re: new itemscope or not?

From: Gregg Kellogg <gregg@greggkellogg.net>
Date: Fri, 7 Sep 2012 20:09:02 -0400
To: Jeni Tennison <jeni@jenitennison.com>
CC: Ed Summers <ehs@pobox.com>, "Dawson, Laura" <Laura.Dawson@bowker.com>, Thad Guidry <thadguidry@gmail.com>, "public-vocabs@w3.org" <public-vocabs@w3.org>
Message-ID: <B8E77C2F-1653-4E4F-8E99-3FD25C4AA4D8@kellogg-assoc.com>
On Sep 7, 2012, at 12:16 PM, "Jeni Tennison" <jeni@jenitennison.com> wrote:

> On 7 Sep 2012, at 20:03, Ed Summers wrote:
>> It would be interesting to know if the HTML spec allowed multiple
>> identifiers, similar to how other HTML attributes work:
> "The itemid attribute, if specified, must have a value that is a valid URL potentially surrounded by spaces."
> http://www.w3.org/TR/microdata/#attr-itemid
> So that would be 'no', not according to spec.
> I've often wondered whether the schema.org 'url' property is meant to be synonymous with itemid. I'm not sure what happens in schema.org interpreters when you specify one/other/both/multiple urls...

Hi Jeni,

Probably not like @itemid, but it could probably be defined to have a value which is an object, rather than a literal when converted to RDF. We might could explore spec language for asserting that.

The fact that URNs can't be used as subjects (or non-literal objects) makes it difficult to use microdata for anything that's not a URL. Also, few schema.org examples even use @itemid. The original purpose of microdata is to provide structure to data in HTML, not as an RDF serialization format; it can be used for this, but in IMO, that's more for allowing the use of RDF tool chains, rather than for creating a true linked data graph.


> Jeni
> -- 
> Jeni Tennison
> http://www.jenitennison.com
Received on Saturday, 8 September 2012 00:09:57 UTC

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