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SOG Speed Over Ground, This is the ship’s relative speed to the ground.
SPEED The speed mainly measured by the GPS.
STW Speed Through Water.
Subnet mask Value for identifying the network address
Symbol information Information of symbols displayed on the plotting screen. The
information includes symbol positions, comments, etc.
TD Abbreviation of Time Difference. Time difference from the
master-station signal of the loran system to the slave-station signal.
Message Type 0 SBAS satellite test broadcasting.
UTC Abbreviation of Coordinated Universal Time.
XTD alarm This alarm informs that the own ship has got out of the scheduled
route by the preset distance or more.