Furuno FMD-3200 Operator's Manual page 301

APPENDIX 2 ABBREVIATIONS, SYMBOLS
Symbol name and description Symbol graphic(s)
Target past positions
AIS aid to navigation (ATON)
Real ATON is without "V" and virtual ATON is with
"V".
An ATON in off position is red.
AIS search and rescue transmitter -SART
AP-13