This standard defines the functionality and principle interfaces for the Common Functional Module (CFM) to ensure the interoperability of Common Functional Modules and provides design guidelines to assist in implementation of such a CFM. It is one of a set of standards that define an ASAAC (Allied Standard Avionics Architecture Council) Integrated Modular Avionics System. This definition of interfaces and functionality allows a CFM design that is interoperable with all other CFM to this standard, that is technology transparent, that is open to a multi-vendor market and that can make the best use of COTS technologies. Although the physical organisation and i