This Specification was written to support future aeronautical applications and services beyond those using Transmission Control Protocol/Internet Protocol (TCP/IP). The initial focus is to support air/ground applications using the Aeronautical Telecommunications Network (ATN). These include Controller-Pilot Data Link Communication (CPDLC), Flight Information System (FIS), and Context Management Application (CMA). Supplement 1 was written to allow interoperation with non-IP protocols and services and upper layer services with respect to the OSI reference model. Supplement 1 reflects ICAO Aeronautical Communication Panel recommendations.