AIM 8/15/19  TBL 5 − 3 − 8 Voice Communications Uplink Message Elements (COMU) TBL 5 − 3 − 9 Voice Communications Downlink Message Elements (COMD) CPDLC Message Sets Operational Definition in PANS − ATM (Doc 4444) FANS 1/A ATN B1 Response Message  Element  Identifier Message Element Intended Use Format for  Message Element Display UM117 CONTACT (ICAO unit name) (frequency) UM117 CON- TACT  (unit name) (frequency) W/U COMU − 1 Instruction to es- tablish voice con- tact with the speci- fied ATS unit on the specified fre- quency. CONTACT (unit name) (frequency) UM120 MONITOR (ICAO unit name) (frequency) UM120 MONI- TOR ( unit name) (frequency) W/U COMU − 5 Instruction to mon- itor the specified ATS unit on the specified frequen- cy. The flight crew is not required to establish voice contact on the fre- quency. MONITOR  (unit name) (frequency) CPDLC Message Sets Operational Definition in PANS − ATM (Doc 4444) FANS 1/A ATN B1 Response Message  Element  Identifier Message Element Intended Use Format for  Message Element Display DM20 REQUEST VOICE CONTACT Note −  Used when a frequency is not re- quired. N/A Y COMD − 1 Request for voice contact on the spec- ified frequency. REQUEST VOICE CONTACT (frequency) TBL 5 − 3 − 10 Emergency/Urgency Uplink Message Elements (EMGU) CPDLC Message Sets Operational Definition in PANS − ATM (Doc 4444) FANS 1/A ATN B1 Response Message  Element  Identifier Message Element Intended Use Format for  Message Ele- ment Display Used in combination with LVLU − 6 and LVLU − 9, which is implemented in  FANS 1/A as: UM38 IMMEDIATELY CLIMB TO ( altitude ) UM39 IMMEDIATELY DESCEND TO ( altitude ) N/A N EMGU − 2 Instruction to im- mediately comply with the associated instruction to avoid imminent situation. Immediately En Route Procedures 5 − 3 − 7