The UDEF is currently being revised by the UDEF project team. This process will produce a standard that better suits the needs of business-to-business communication, but the result is not expected to be backwards-compatible with current UDEF. Further details will appear as the development proceeds.
The Universal Data Element Framework (UDEF) is a framework for describing data to enable interoperability. Enterprise and standard specialist vocabularies can be related to each other within the UDEF. A particular feature is support for equivalent vocabularies in different languages. It is easy to use, and its definitions are readily available on-line.
These pages will help you to understand what the UDEF is, how to use it, and the architecture that is envisaged for distributed UDEF operation. The complete set of UDEF definitions is available on the web, and the UDEF Project Plato page contains information about the UDEF Project.