The aeronautical industry has recognized the need to apply standard communications protocols and services using the OSI Reference Model. The aeronautical industry has chosen to implement standard protocols within their data communications systems, as appropriate, and to use products and services which have already been developed in accordance with appropriate existing, internationally-accepted, data-communications standards.

The aeronautical industry also recognizes that certain applications that utilize data communications do not have well defined nor widely used solutions within the strict context of the OSI Reference Model. Often, they have no solution at all using the OSI standard protocols. The aeronautical industry has, therefore, decided not to limit the middle and upper layer protocols associated with this Specification to those conforming to the OSI protocol suite as defined by ISO.

The OSI Reference Model was developed to provide a common basis for the coordination of standards development for the purpose of integrating data communications systems. The OSI Reference Model itself does not achieve the goal of interoperability; however, it does serve as the catalyst to enable independent development of standard protocols that ultimately achieve the goal of interoperability within the selected protocol stack (for example, OSI, TCP/IP, or others). Part 2 is based on ISO/IEC/IEEE 8802-3:2014.