5─7 
Types and Definitions of AIS Symbols 
 
Vector/Symbol Definition  Remarks 
 
Sleeping target 
This symbol is displayed when received data 
is valid. 
The direction of the triangle’s vertex indicates 
the target’s bow or COG. 
 
Activated target 
The heading direction is displayed with a 
solid line, and the COG vector is displayed 
with a dotted line. The line perpendicular to 
the heading direction indicates the direction to 
which the course is to be changed.    This line 
may not be displayed. 
 
Numeric-displayed target 
This symbols is displayed around the target 
for which numeric data is displayed. 
 
Dangerous target 
Alarm characters (CPA/TCPA) 
An alarm sounds. 
The characters are displayed in red and the 
symbol is blinks. 
 
Lost target 
The dangerous target is regarded as a lost 
target when data cannot be received for 
specified time. When it is determined as a lost 
target, this symbol is displayed at the position 
calculated from the last-received data such as 
the course and speed.