**HU** - head unit, the dash mounted radio/cd/cassette player.


**[[RTI]]** - road traffic information. Provides mapping and navigation. Consists of base unit in the trunk of the car and motorised screen in dash.


**[[MELBUS]]** - (Mitsubishi Electric BUS)?
Communication interface found in Volvo cars and used for communication between HU and various audio sources- CD changer, RTI unit, TV tuner and others.