RE: XG Talk during the W3C Advisory Committee Meeting -- IPTC andCURIEs

[Apologies for the earlier typo in the name of the yahoogroup]

Hi Raphaël,

> >  The new generation of IPTC standards is based on
> > the use of Qualified Codes (QCodes) which are very different
> > from CURIEs.  Confusion between the two doesn't do anyone any
> > good.
> 
> I agree and I'm even now writing some text for highlighting the 
> differences :-)

That's good.  The main differences are ...

CURIEs (as I understand them) are a mechanism for abbbreviating URIs 
by splitting the URI at an arbitrary point into two parts, 
associating the left part with an alias and then writing (I don't 
know the current syntax), something like:

   alias:right/hand/side

For example, the URI:

   http://www.w3.org/2005/Incubator/mmsem/

could be written as any of these:

   x:/

   x:sem/

   x:mmsem/

   x:/mmsem/

   x:bator/mmsem/

   x:Incubator/mmsem/

   etc

QCodes, on the other hand, are very much like QNames.  A QCode is a 
tuple, made up of:

   a scheme URI, mapped to a scheme alias

   a code

So this could be a legal QCode:

   Scheme = http://www.iptc.org/NewsCodes/Subject/ -> "ncs"

   Code   = 17003001 ("weather news")

   QCode  = ncs:17003001

These, however, would *not* be legal QCodes:

            ncs:Subject/17003001

            ncs:Codes/Subject/17003001

            ncs:NewsCodes/Subject/17003001

            etc

Unlike both QNames and CURIEs, QCodes require that both the scheme 
URI and the code URI be dereferenceable.

Misha Wolf
News Standards Manager, Reuters
Chair, News Metadata Framework WG, IPTC

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Received on Tuesday, 8 May 2007 16:09:13 UTC