Garmin 20 Pilot's Manual page 142

Appendix
Abbreviations
TRK — Track (also Ground Track)
UAT — Universal Access Transceiver
UNR — Unrestricted
VFR — Visual Flight Rules
VOL — Volume
VOR — VHF Omnidirectional Radio
Range
WB — Warning Boxes
WX — Weather
XPDR — Transponder
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