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Re: Microdata: itemid attribute (feedback)

From: Ian Hickson <ian@hixie.ch>
Date: Sun, 25 Oct 2009 04:11:15 +0000 (UTC)
To: Martin McEvoy <martin@weborganics.co.uk>
Cc: public-html@w3.org
Message-ID: <Pine.LNX.4.62.0910250318570.13521@hixie.dreamhostps.com>
On Sat, 24 Oct 2009, Martin McEvoy wrote:
> 
> Just some thoughts on the itemid and the itemref attributes
> 
> I am unsure if itemid has any actual practical use (either that of I am 
> misunderstanding something).
> 
> Itemid is used as a global Identifier for an Item, its value must be 
> valid absolute url, what I am unsure of is how to actually use this? 
> here is how I am guessing it should be used.
> 
> <div id="a"
>     itemid="http://organization.com/#a"
>     itemscope
>     itemtype="http://microformats.org/profile/hcard">
>    <a itemprop="url fn org" href="http://organization.com/">
>      Example Oranization
>    </a>
> </div>
> 
> If this is correct then it seems a little like I am repeating data that 
> already exists? itemid seems like it is just a long form version of the 
> data available using id.  I do see itemid as being useful for data that 
> is *not* a url in the traditional sense, such as in the example that 
> uses urn's

The itemid attribute is only useful for vocabularies that use it. This 
will mostly be vocabularies intended for use with RDF systems -- RDF 
systems name lists of name-value pairs all the time. itemid="" in 
Microdata is basically equivalent to about="" in RDFa.

-- 
Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Sunday, 25 October 2009 03:58:17 GMT

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