This standard provides the operational@ safety@ and performance requirements (SPR) for the implementation of data communication services that support air traffic services (ATS). It provides with provision of data communications in all operational environments e.g.@ continental@ oceanic@ and surface. It is intended to support the communication element of the implementation of communication@ navigation@ and surveillance / air traffic management (CNS/ATM) systems in worldwide application. Data link communications are expected to be used for routine or frequent types of transactions@ as well as for communication functions in which the use of voice communication is considered inefficient or unnecessary@ thereby reducing voice-channel use and@ where resulting controller workload reduction allows increases in sector size@ reduction in the number of required voice channels. This SPR standard is intended for use with interoperability requirements (INTEROP) standards@ and the guidelines described in RTCA DO-264/EUROCAE ED-78A.