External Reference Data is Reference Data that is maintained by an authority outside the enterprise. The ISO 3166-1 Country standard and the North American Industrial Classification System (NAICS) are examples of this. However, there are two major ways in which External Reference Data standards are updated.
One way is that the standard changes is incrementally, every time there is an underlying change. So, when a new country appears in the United Nations, or when a county informs the UN that it is changing its name, then the ISO 3166-1 standard will be updated and a communication issued to subscribers informing them of the change. We call this a “delta” approach
By contrast, the NAICS standard is updated entirely once every 5 years. This is what we call a “point release”. What is happening here is that the standard is actually being redesigned from within by the authority, rather than accumulating events that are outside the control of the authority that maintains the standard (as is the case with ISO 3166-1). So NAICS is an ontology that is entirely the product of a single authority, whereas ISO 3166-1 is a compilation of ontological commitments that are developed by isolated agents that do not work in concert.
Actually, the ISO 3166-1 standard also is completely updated every 5 years, but this is by consolidation of all the deltas.
The more important point is that we have some centralized organizations that are developing ontologies, whereas there are others that are consolidating what others have done. This is an area that needs to be explored more as it may have profound implications for Reference Data Management.