This Recommendation | International Standard is to be applied by reference from other specifications. This is done within such specifications by reference to the CCR services defined in ITU-T Rec. X.851 | ISO/IEC 9804. A reference to a CCR service invokes the procedures of this Recommendation | International Standard to cause external effects. This Recommendation | International Standard specifies, in clause 9, a use of the ACSE, Presentation and Session services to carry the CCR semantics. This "reference" mapping can be used whenever the use of these services does not conflict with the user made by other ASEs or ASOs that are using the same association. Annex B defines how a different use of supporting services may be specified, for use where the reference mapping is inappropriate. This Recommendation | International Standard specifies the static and dynamic conformance requirements for systems implementing these procedures. It does not contain tests which can be used to demonstrate conformance. This edition of this Recommendation | International Standard specifies CCR protocol Version 2, which makes use of the Session Data Separation functional unit to protect data not belonging to the CCR atomic action. The 1990 edition of ISO/IEC 9805 specified CCR protocol Version 1. The 1993/1994 edition of this Recommendation | International Standard specified both CCR protocol Version 1 and CCR protocol Version 2, for the static commitment functional unit only. This International Standard specifies the protocol elements that support the following functional units: a) static commitment; b) dynamic commitment; c) read only; d) one-phase commitment; e) cancel; and f) overlapped recovery.