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[Bug 19016] New: Microdata doesn't allow marking up content with multiple vocabularies

From: <bugzilla@jessica.w3.org>
Date: Tue, 25 Sep 2012 21:53:35 +0000
To: public-html@w3.org
Message-ID: <bug-19016-2495@http.www.w3.org/Bugs/Public/>
https://www.w3.org/Bugs/Public/show_bug.cgi?id=19016

           Summary: Microdata doesn't allow marking up content with
                    multiple vocabularies
           Product: HTML WG
           Version: unspecified
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: HTML5 spec
        AssignedTo: dave.null@w3.org
        ReportedBy: contributor@whatwg.org
         QAContact: public-html-bugzilla@w3.org
                CC: ian@hixie.ch, mike@w3.org,
                    public-html-wg-issue-tracking@w3.org,
                    public-html@w3.org, philipj@opera.com,
                    kennyluck@w3.org


This was was cloned from bug 13527 as part of operation LATER convergence.
Originally filed: 2011-08-02 19:37:00 +0000
Original reporter: Richard Cyganiak <richard@cyganiak.de>

================================================================================
 #0   Richard Cyganiak                                2011-08-02 19:37:05 +0000 
--------------------------------------------------------------------------------
There are situations where content authors have the choice between multiple
overlapping microdata vocabularies. For example both schema.org/PostalAddress
and vCard are available for marking up postal addresses. Microdata forces
content authors to either choose one of them (schema.org 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:
http://www.w3.org/Bugs/Public/show_bug.cgi?id=13470

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="http://schema.org/PostalAddress
streetAddress addressLocality addressCountry">
    <meta itemprop="altitem" content="http://microformats.org/profile/hcard
street-address locality country-name">
</div>

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 schema.org typed item with three properties; one vCard
typed item with three properties. This proposal is fleshed out here:
http://richard.cyganiak.de/blog/2011/08/multiple-itemtypes-in-microdata/

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.
================================================================================
 #1   Ian 'Hixie' Hickson                             2011-08-02 21:15:24 +0000 
--------------------------------------------------------------------------------
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:
   http://dev.w3.org/html5/decision-policy/decision-policy.html

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.
================================================================================

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Received on Tuesday, 25 September 2012 21:53:36 UTC

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