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Bug 13527 - microdata: Marking up items using multiple unrelated vocabularies
Summary: microdata: Marking up items using multiple unrelated vocabularies
Alias: None
Product: WHATWG
Classification: Unclassified
Component: HTML (show other bugs)
Version: unspecified
Hardware: All All
: P4 enhancement
Target Milestone: Unsorted
Assignee: Ian 'Hixie' Hickson
QA Contact: HTML WG Bugzilla archive list
Depends on:
Reported: 2011-08-02 19:37 UTC by Richard Cyganiak
Modified: 2014-05-07 18:46 UTC (History)
7 users (show)

See Also:


Description Richard Cyganiak 2011-08-02 19:37:05 UTC
There are situations where content authors have the choice between multiple overlapping microdata vocabularies. For example both and vCard are available for marking up postal addresses. Microdata forces content authors to either choose one of them ( because that's what Google supports), or to duplicate their content.

The challenge with supporting multiple vocabularies in microdata is how to associate property names with the vocabularies in absence of vocabulary knowledge. This difficulty has been stated as the reason for rejecting a similar issue here:

The ambiguity can be avoided by generating multiple items from a single itemscope, with one type each. For example:

<div itemscope>
    <span itemprop="streetAddress street-address">26 Dun Aengus</span>,
    <span itemprop="addressLocality locality">Galway</span>,
    <span itemprop="addressCountry country-name">Ireland</span>.
    <meta itemprop="altitem" content=" streetAddress addressLocality addressCountry">
    <meta itemprop="altitem" content=" street-address locality country-name">

The altitem property would have to be a microdata built-in property that affects microdata parsing. Its value would be a whitespace-separated list; its effect would be to generate a new alternate item whose itemtype is the first URL from the list. The rest of the list are property names to be copied from the itemscope. The result here would be three items; one untyped item with eight properties; one typed item with three properties; one vCard typed item with three properties. This proposal is fleshed out here:

The point of this example is to argue that support for multiple vocabularies in microdata is possible in a way that is more convenient to authors than forcing them to repeat content.
Comment 1 Ian 'Hixie' Hickson 2011-08-02 21:15:24 UTC
EDITOR'S RESPONSE: This is an Editor's Response to your comment. If you are satisfied with this response, please change the state of this bug to CLOSED. If you have additional information and would like the editor to reconsider, please reopen this bug. If you would like to escalate the issue to the full HTML Working Group, please add the TrackerRequest keyword to this bug, and suggest title and text for the tracker issue; or you may create a tracker issue yourself, if you are able to do so. For more details, see this document:

Status: Partially Accepted
Change Description: none yet
Rationale: I have marked this LATER so that we can examine it in more detail once microdata has seen significant adoption. It's not clear that this is a problem that will actually be seen in the wild.
Comment 2 Michael[tm] Smith 2011-08-04 05:05:18 UTC
mass-move component to LC1
Comment 3 Michael[tm] Smith 2013-01-24 08:00:12 UTC
This bug was cloned to create HTML WG bug 19016.
Comment 4 Ian 'Hixie' Hickson 2013-03-19 23:32:41 UTC
Are there examples of pages publishing data in multiple vocabularies that are all processed by different data analysis tools?
Comment 5 Ian 'Hixie' Hickson 2013-10-22 21:53:11 UTC
In the absence of any data showing people actually would benefit from this, it's not clear why we'd add it.
Comment 6 Ian 'Hixie' Hickson 2014-05-07 18:46:55 UTC
Given the low level of demand for this feature (hardly anyone has shown any pages that are affected by not having this feature), I think we should punt on it.