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Multiple itemtypes in microdata

From: Jeni Tennison <jeni@jenitennison.com>
Date: Wed, 12 Oct 2011 18:56:22 +0100
Message-Id: <75C4C3C3-1FEB-44CD-A702-5CFB8AAD940C@jenitennison.com>
Cc: public-html-data-tf@w3.org
To: Ian Hickson <ian@hixie.ch>

It's good to see you addressing the requirement for multiple itemtypes in microdata [1]. However, the "same vocabulary" requirement on those types seems problematic for publishers.

One of the assumptions we're making within the HTML Data TF is that publishers will need to publish in multiple formats (rather than consumers understanding multiple formats) so that when/if there is eventual convergence on a single format, consumers aren't stuck having to be able to maintain a massive legacy. [2] This applies to both syntax and vocabulary.

If people are using multiple vocabularies they will very probably want to use types from each of those vocabularies. An example of the kind of workaround that's currently being recommended is shown with the use of GoodRelations with schema.org [3] where the ugly http://www.w3.org/1999/02/22-rdf-syntax-ns#type property is used to provide the GoodRelations type for the item while the itemtype holds the schema.org type. As you know, I've also blogged about this from the perspective of a publisher targeting both browsers and search engines. [4]

You've put a NEEDSINFO status on the bug which makes me wonder if you're still thinking about this requirement and whether there's any information we could provide you with? If support for multiple types from different vocabularies is definitely out of scope for microdata, it would be really helpful to understand the rationale so that we can document it for users.



[1] http://www.w3.org/Bugs/Public/show_bug.cgi?id=14233
[2] http://lists.w3.org/Archives/Public/public-html-data-tf/2011Oct/0024.html
[3] http://lists.w3.org/Archives/Public/public-vocabs/2011Oct/0028.html
[4] http://www.jenitennison.com/blog/node/161
Jeni Tennison
Received on Wednesday, 12 October 2011 17:56:47 UTC

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