Change 2 to ED-110B/DO-280B, Interoperability Requirements Standard for Aeronautical Telecommunication Network Baseline 1 (ATN B1 Interop Standard) contains the following updates: •Update the ground requirement in section 3.3.7.6.4.10.2 regarding UM79 content; •Update the ground requirements in Tables 4-3 and 4-5 and associated figures regarding message concatenation in CPDLC end requests.