This Recommendation / International Standard covers the concepts which are needed to perform the modelling of ODP systems (see clauses 6 to 14), and the principles of conformance to ODP systems (see clause 15).The concepts defined in clauses 6 to 14 are used in the Reference Model of Open Distributed Processing to support the definitions of:a) the structure of the family of standards which are subject to the Reference Model;b) the structure of distributed systems which claim compliance with the Reference Model (the configuration of the systems);c) the concepts needed to express the combined use of the various standards supported;d) the basic concepts to be