Cockpit Management and Data system - COMAND for short - acts as a combined command and control centre for all audio, telematics and telecommunications functions on Mercedes-Benz vehicles and includes a dedicated flat display screen. In addition to the GPS navigation system and general processing and control logic, COMAND includes components such as an address book, telephone, radio and in many cases a CD/DVD drive. It is connected to other (often separate) devices such as CD/DVD changers, sound system and surround sound amplifier, TV receiver and the optional Linguatronic voice control system via an optical fibre network. The first generations of COMAND used the D2B optical network standard whereas later models are based on MOST.