47 C.F.R. § 87.171
The two or three letter symbols for the classes of station in the aviation services are:
Symbol and class of station
AX-Aeronautical fixed
AVW-Audio visual warning systems
AXO-Aeronautical operational fixed
DGP-Differential GPS
DLT-Aircraft data link land test
FA-Aeronautical land (unspecified)
FAC-Airport control tower
FAE-Aeronautical enroute
FAM-Aeronautical multicom
FAR-Aeronautical search and rescue
FAS-Aviation support
FAT-Flight test
FAU-Aeronautical advisory (unicom)
FAW-Automatic weather observation
GCO-Ground Communication Outlet
MA-Aircraft (Air carrier and Private)
MA1-Air carrier aircraft only
MA2-Private aircraft only
MOU-Aeronautical utility mobile
MRT-ELT test
RCO-Remote Communications Outlet
RL-Radionavigation land (unspecified)
RLA-Marker beacon
RLB-Radiobeacon
RLD-RADAR/TEST
RLG-Glide path
RLL-Localizer
RLO-VHF omni-range
RLS-Surveillance radar
RLT-Radionavigation land test
RLW-Microwave landing system
RNV-Radio Navigation Land/DME
RPC-Ramp Control
TJ-Aircraft earth station in the Aeronautical Mobile-Satellite Service
UAT-Universal Access Transceiver
47 C.F.R. §87.171