XBRL International has published a document which can shed a tremendous amount of information on XBRL, XBRL taxonomies, and XBRL instances if one is interested in this sort of thing. The document is the Comparison Framework for EDINET, IFRS, and US GAAP XBRL Taxonomies.
What the TCF (taxonomy comparison framework) is trying to achieve is best understood from the executive summary of the document which says:
The effort to provide a comprehensive comparison framework is a deliverable of the Interoperable Taxonomy Architecture project (ITA). The ITA is a joint initiative between the US SEC, the Japan FSA, the European Commission and the IASC Foundation XBRL team, and aims to converge the XBRL architectures of three taxonomies: EDINET, IFRS and US GAAP. In the project's first stage, the three respective taxonomy developers agreed to develop a comprehensive framework which would provide a basis for comparison of the three taxonomy architectures. The result was the Taxonomy Comparison Framework (TCF). The ITA project assumed a scope of analysis limited to financial reporting in capital markets. Although XBRL taxonomies are often used in other reporting scenarios (for example bank regulation, statistical reporting or tax reporting) such usage of XBRL taxonomies was out of scope of the ITA and thus is not analysed in the TCF.
There are two specific things which I am personally interested in relating to this document.
The first item of interest is the possibility of creating one global framework for financial reporting. As a CPA, I personally believe that one framework which makes us of IFRS (International Financial Reporting Standards) and XBRL would be a very good thing. The next 10 years will tell if the the business community and in particular those who participate in the financial reporting supply chain have the resolve to make this a reality. I would be the first to admit that I don't have a full understanding of the issues involved in creating one globally used framework. However, I do believe that such a framework would be a very good thing. Further, I hope that the US does not hold this effort back. Technically, creating such a framework is very possible from what I see looking at IFRS and XBRL. I think this all boils down to the will to do it.
The second item of interest is the need to actually do a comparison of the different architectures of these three financial reporting XBRL taxonomies. After all, all are XBRL. All are for financial reporting. They should all interoperate because they are XBRL. Right? Well, no. This is something that many people still don't seem to get about XBRL. People need to understand this about XBRL, otherwise they will make big mistakes in implementing XBRL. This is not a problem with XBRL, it is a reality of what XBRL is. XBRL is a general purpose specification. It is quite flexible, it was constructed to be flexible for a reason. Business reporting is a broad category, a broad set of use cases. Think about this. Take a look at the comparison of the three taxonomies. The question that I have is how to avoid having to do such comparisons in the first place. Another way of saying this is how is interoperabilty maximized? I think I am seeing how to do this. Look for a blog entry in the near future which talks about how XBRL is similar to shipping containers. It may seem odd, but there is something to be learned about building XBRL taxonomies from those big metal boxes used to transport goods on ships. Look for it.