This metadata stuff keeps getting more and more interesting. A post I made to the LinkedIn group Semantic XBRLled to someone mentioning SKOS.
SKOS, or Simple Knowledge Organization System is a standard way to express metadata. A W3C recommentation, is described this way by an introduction to SKOS:
SKOS provides a standard way to represent knowledge organization systems using the Resource Description Framework (RDF). Encoding this information in RDF allows it to be passed between computer applications in an interoperable way.
Using RDF also allows knowledge organization systems to be used in distributed, decentralised metadata applications. Decentralised metadata is becoming a typical scenario, where service providers want to add value to metadata harvested from multiple sources.
Here is a SKOS primer. Here is a SKOS wiki. Here is an introduction to SKOS provided by XML.COM. Here is a SKOS reader. RDF-Gravity reader.
This is how I see it. You can express metadata using any ole XML. But, there is leverage if you not only use XML, but rather use the standard such as RDF/OWL. But even using RDF/OWL you have a lot of flexibility as to how to express things. SKOS provides an even higher level standard than RDF/OWL for the specific purpose of expressing metadata used in knowledge management systems.
So I used RDF/OWL to express the major categories, topics, disclosure objects, and disclosure templates used for some things I am trying to achieve relating to financial reporting using US GAAP. Here is that metadata.
Seems that following the SKOS standard provides an even higher level of possible interoperability. Could be wrong, but SKOS seems like the way to go, a standard form of RDF/OWL for the sort of metadata I need to model.