W3C home > Mailing lists > Public > public-vocabs@w3.org > June 2014

The exact meaning of a 'global identifier' (itemid)

From: Jarno van Driel <jarnovandriel@gmail.com>
Date: Mon, 9 Jun 2014 20:24:12 +0200
Message-ID: <CADK2AU391XAQUdJeF-LO0fFYb8HHGoQePfNc=yTasp1sX9W6Eg@mail.gmail.com>
To: W3C Web Schemas Task Force <public-vocabs@w3.org>
I would like to know if the exact meaning of a Microdata global identifier
(itemid) has been documented?

I've been working on some test code to find out what can and cannot be
achieved by using @itemid and unfortunately I can't fully wrap my brain
around it since the different testing tools end up giving me different

Now I've tried to look for info about @itemid on schema.org but can't find
anything. The only info out there I could find just says it should be
documented by the vocabulary itself.


During my testing I got the impression the structured data linter is the
only tool that gets my markup right, but that's looking at it from an RDFa

What is schema.org's perspective on this:

    <div itemid="CorporationPerson" itemscope itemtype="
        <a itemprop="url" href="http://www.example.org">www.example.org</a>

    <div itemid="Product" itemscope itemtype="http://schema.org/Product">
        <span itemprop="name">Donald Duck DVD</span>
        <link itemprop="brand" href="CorporationPerson" />
        <span itemprop="offers" itemscope itemtype="http://schema.org/Offer
            $<span itemprop="price">19.95</span>
            <meta itemprop="priceCurrency" content="USD">

    <div itemid="CorporationPerson" itemscope itemtype="
        <span itemprop="name">Walt Disney</span>

note: I'm not looking for @itemref solutions, extra <links> or different
order of HTML, those I can come up with myself just fine. I really just
want to know the workings of @itemid from a schema.org perspective.

Any thoughts?

*Jarno van Driel*
Technical & Semantic SEO Consultant
8 Digits - Digital Marketing Technologies

Tel: +31 652 847 608
Google+: https://plus.google.com/u/0/+JarnovanDriel
Linkedin: linkedin.com/pub/jarno-van-driel/75/470/36a/
Received on Monday, 9 June 2014 18:24:39 UTC

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