NorthStar 957 Operator's Manual page 189

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.
track
A desired line of travel, or path already travelled.
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.
957 Operator's Manual, Rev. B Page 181