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Re: advice on modeling an XBRL fact as a triple

From: Dave Raggett <dsr@w3.org>
Date: Tue, 16 Sep 2008 14:53:48 +0100 (BST)
To: Bob DuCharme <bob@snee.com>
cc: semantic-web@w3.org
Message-ID: <alpine.DEB.1.00.0809161408330.6785@holly>

On Mon, 15 Sep 2008, Bob DuCharme wrote:

>> One question is the namespace for describing XBRL instances. Is 
>> it better to the preexisting xbrli 
>> <http://www.xbrl.org/2003/instance> namespace instead of a 
>> generic XBRL namespace?
>
> Even though that namespace wasn't designed specifically for use in 
> the predicates of RDF triples, it's the namespace defined by the 
> standard, so I'm going to go with that for now instead of defining 
> yet another namespace. If a specific XBRL ontology gets any 
> traction, I'll use it instead of defining another one and relying 
> on the presence of OWL awareness to map equivalences.

This is something to taken up with XBRL.org at an appropriate stage.

>> XBRL Linkbases use XLink to refer to element definitions in XBRL 
>> Schemas. The URI for the schema depends on the server it has been 
>> copied to, e.g. the EDGAR archive. It may be better to use the 
>> target namespace for the schema and element name, in place of the 
>> schema URI and element definition id.
>
> This is just the kind of thing that has me concentrating on the 
> instance documents for now and forgetting about the XBRL taxonomy 
> documents for now. I'll defer to your judgment!

I see this in terms of provenance, i.e. who has contributed what. A 
company might extend the USGAAP taxonomy, and it makes sense for 
those extensions to be in a namespace owned by that company. The 
namespace for standard taxonomies is owned by the entity that define 
them.

An example is the SEC taxonomies for accountants reports, see
http://www.sec.gov/spotlight/xbrl/taxon-nongaap.htm which defines a 
number of namespaces, e.g.

   Core AR taxonomy:
     http://xbrl.us/ar/2008-01-31
   Core AR Taxonomy Including Linkbases
     http://xbrl.us/ar-std/2008-01-31
   etc.

The XBRL.org site provides a useful set of links to GAAP taxonomies,

       http://www.xbrl.org/FRTaxonomies/

e.g. Ireland's GAAP Commercial and Industrial taxonomy is defined to 
have the namespace:

      http://www.xbrl-ie.org/public/ci/2006-12-31

but when you look at the associated schema, the target namespace is

      http://www.xbrl-ie.org/ie/fr/gaap/ci/2006-12-31

A similar situation holds with respect to the XBRL US GAAP Taxonomy 
1.0 which is defined to have the namespace:

     http://xbrl.us/us-gaap/2008-03-31 (all elements)

but the target namespace for the core schema is:

     http://xbrl.us/us-gaap-std/2008-03-31

so it isn't quite clear which one to use. A translation program 
either has to have prior knowledge of which namespace to use, or has 
to use some kind of discovery process. I am exploring what might be 
done by building on top of the rules for the XBRL Discoverable 
Taxonomy Set.

Other issues for translating linkbases include the precise meaning 
of terms in the XBRL specification, and how to deal with taxonomy 
overrides. For example is the XBRL parent-child relationship the 
inverse of rdfs:subClassOf?

  Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett
Received on Tuesday, 16 September 2008 13:54:30 GMT

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