NorthStar 958 Operator's Manual page 217

secondaries
The "slave" loran transmitters in a chain of at least three
stations.
SNR
Signal-to-Noise Ratio. Guide number for determining the
relative quality of GPS, DGPS, or loran signals as compared to
background radio "noise."
SOG
Speed Over Ground. The actual speed of your vessel relative to
the sea bottom.
TD
Time Difference. The measured amount of time—in millionths
of a second—between loran signals received from the master
and the secondary stations.
target
Boats or ships, navigational markers, land masses, or any other
object detected by radar.
track
A desired line of travel, or path already travelled.
VRM
Variable Range Marker. A circle on the radar, surrounding one
of the end points of the electronic bearing line, used to
measure distances from that end point to any other point of
interest on the screen.
WAAS
Wide Area Augmentation System.
waypoint
A particular location (defined for navigation purposes by its
lat/lon, distance and bearing, or TDs), used as an intermediate
or final destination.
958 Operator's Manual, Rev. A Page 209