Cube interface for USV and external NAV

Hello

Can somebody direct me to the place outlining the configuration of the Cube when operating with external sensors for all navigation data. Cube would be connected to the single water-jet steering nozzle controlling the direction of the surface vehicle.
I am looking into the interface control document outlining the interface and commands of what messages the Cube would need to drive the vessel between way points or running a straight line.
Does it work similarly to to NMEA APB or it requires other messages?

thanks in advance.
Pawel