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Re: Microdata: itemid attribute (feedback)

From: Martin McEvoy <martin@weborganics.co.uk>
Date: Sun, 25 Oct 2009 10:23:58 +0000
Message-ID: <4AE4273E.2030403@weborganics.co.uk>
To: Ian Hickson <ian@hixie.ch>
CC: public-html@w3.org
Hello Ian,

Ian Hickson wrote:
> 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.

That what I thought,  a good example of how this may be useful is (in 
RDF terms) setting the subject of  something anywhere on the web not 
just locally.
I *can* use @id If  I like (for locally defined items indeed I probably 
should ) its just @itemid is explicit.

I had a short discussion off list that helped me confirm this.


Martin McEvoy

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Received on Sunday, 25 October 2009 10:24:26 UTC

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