AIS	automatic identification system
ARCS	admiralty raster chart system
ARPA	automatic radar plotting aid
ATT	admiralty tide table
BWW	bearing waypoint to waypoint
BTW	bearing to waypoint
CD	chart datum
MSL	mean sea level
LAT	lowest astronomical tide
CEP	circular error propable
CM	chart manager utility
CMG	course made good
COG	course over ground
CPA	closest point of approach
CPP	controllable pitch proppeler
CTW	course through water
DIST	distance
DGPS	Differential Global Positioning System
DR	Dead Reckoning