When over ATS with MTI RCL it is used for Oceananic Clearance Request.
/EGGX.OC1/RCL 046
AFR088-BALIX/1754 M083F360
-RMK/MAX F3701C22
/KZOA.OC1/RCL 024
EDDIE92-DINTY/1923 M079F3801CA8
ACARS clerance request made by DAL137, flying Amsterdam to Detroit in ACARS message 851290567
/PIKCLXS.OC1/RCL 040
DAL137-PIKIL/1405 M082F370
-RMK/D3DD
...
/<Recipient authority>.OC1/RCL /<Request ID number> <Callsign>-<Oceaninc entry waypoint>/<ETA to oceanic entry waypoint> <Requested Mach number><Requested flight level> -RMK/<Any typed remarks or other requests><Checksum four digits>
- Recipient authority could be the FIR code, e.g. EGGX or KZOA, or it could be a SITA(?) address, e.g. PIKCLXS
- Remarks are not required but are possible, there are examples in Appendix B of this document
EGGX = ATC Oceanic Center AFR088 = Flight Number or Callsign BALIX = Oceanic Route Entry (Way)Point 1754 = HHMM ETA UTC over Oceanic Route Entry (Way)Point M083 = Mach Number (083=0.83) F360 = Flight Level (360=36000ft)