Defines a framework for describing types of interest in ODP systems by determining what entities need to be typed and what needs to be said about the identified types. The primary focus of this work is the computational interface type system; identifies and characterises type languages sufficient to describe the types identified above in an informative annex; provides enterprise, information, and computational specifications of a generic type repository function within the type description framework which can be specialised to select a specific type system or type notation.