Definitions and symbology of AIS?

Sleeping target

A target symbol indicating the presence and orientation of a vessel equipped with AIS in a certain location. No additional information is presented until activated thus avoiding information overload.

Activated target

A symbol representing the automatic or manual activation of a sleeping target for the display of additional graphically presented information including: a vector (speed and course over ground); the heading; and ROT or direction of turn indication (if available) to display actually initiated course changes.

Selected target

A  symbol representing the manual selection of any AIS target for the display of detailed information in a separate data display area. In this area, received target data as well as the calculated CPA and TCPA values will be shown.

Dangerous target

A symbol representing an AIS target (activated or not) which data contravene pre-set CPA and/or TCPA limits.

Lost target

A symbol representing the last valid position of an AIS target before the reception of its data was lost.