The scope of this document is the ATS applications that support the following air traffic services (ATS): a) Context Management (CM) service: 1) Data Link Initiation Capability (DLIC); b) Controller-Pilot Data Link Communication (CPDLC) services: 1) Air Traffic Control (ATC) Communication Management (ACM); 2) Clearance Request and Delivery (CRD); 3) ATC Microphone Check (AMC); 4) Departure Clearance (DCL); 5) Data Link Taxi (D-TAXI); 6) In-Trail Procedures (ITP); and 7) Oceanic Clearance Service (OCL); c) Automatic Dependent Surveillance ?C Contract Mode (ADS-C) service: 1) Position Reporting (PR); d) Combined services (CPDLC and ADS-C): 1) Information Exchange and Reporting (IER); 2) 4-Dimensional Trajectory Data Link (4DTRAD); 3) Dynamic Required Navigation Performance (DRNP); and 4) Interval Management (IM). These ATS services supported by data communications are described in section 4 to the extent necessary to establish the INTEROP for the application functions needed to support them. The detailed specification of the ATS services can be found in the Baseline 2 SPR@ ED-228A/DO-350A [10]@ Section 3@ ATS Services Purpose The purpose of this document is to define the set of requirements for the interoperability aspects of Baseline 2 data link systems. This document addresses ATN systems but would need to be amended to address other types of data link. This document is intended for use in conjunction with a consistent SPR standard@ other INTEROP standards@ and the guidelines described in ED-78A/DO-264 [7] for each approval type associated with the elements of the CNS/ATM system.