[whatwg] itemtypes from same vocabulary

Lin Clark lin.w.clark at gmail.com
Wed Feb 13 08:23:59 PST 2013

Itemtype cannot reference different vocabs. Here are two relevant
discussions that I know of, one with Hixie and the other with the HTML Data
Task Force.


On Wed, Feb 13, 2013 at 11:18 AM, Ed Summers <ehs at pobox.com> wrote:

> Hi all,
> I am looking for some guidance about the use of multiple itemtypes in
> microdata [1], specifically the phrase "defined to use the same
> vocabulary" in:
> """
> The item types must all be types defined in applicable specifications
> and must all be defined to use the same vocabulary.
> """
> For example, does this mean that I can't say:
> <div itemscope itemtype="http://acme.com/Foo http://zenith.com/Bar"> ...
> </div>
> The reason I ask is that there is some desire over in the schema.org
> community [2] to provide a mechanism for schema.org to be specialized.
> For example, in the case of an audiobook:
> <div itemscope itemtype="http://schema.org/Book
> http://www.productontology.org/id/Audiobook"> ... </div>
> The idea being not to overload schema.org with more vocabulary, and to
> let vocabularies grow a bit more organically. This schema.org group is
> currently thinking of using a one off property additionalType that
> would be used like so:
> <div itemscope itemtype="http://schema.org/Book">
>   <link itemprop="additionalType"
> href="http://www.productontology.org/id/Audiobook">
>   ...
> </div>
> I personally find this to be kind of distasteful since it replicates
> the mechanics that microdata's itemtype already offers.
> So, my question: is it the case that itemtype cannot reference types
> in different vocabularies like the example above? If so, I'm curious
> to know what the rationale was, and if perhaps it could be relaxed.
> //Ed
> [1]
> http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html#items
> [2]
> http://lists.w3.org/Archives/Public/public-schemabibex/2013Feb/0000.html

Lin Clark
Drupal Consultant


More information about the whatwg mailing list