Cockpit Management and Data system - COMAND for short - acts as a combined command and control center 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 fiber network. The first generations of COMAND used the D2B optical network standard whereas later models are based on MOST. A key feature of all COMAND systems is to provide deep integration between the various functions such as multimedia, navigation and telephony and to also allow multiple presentation and control facilities. An example of functional integration is where other audio sources can be muted when a phone call comes in or when navigation guidance is being given. It is also the case that the main audio system, speakers and microphone are used for all these functions instead of being logically and functionally separate. With regard to multiple presentation and control facilities, COMAND-based vehicles allow steering wheel controls to be used alongside the main COMAND buttons and controller and COMAND-related status information and instructions can be displayed in the instrument cluster in addition to the main COMAND display. On vehicles with a factory-fitted Mercedes-Benz rear seat entertainment system, this also provides integration with the COMAND system, allowing for instance the rear seat displays to show content from the COMAND TV receiver or to play out the rear DVD audio over the car's surround sound system. On newer S-Class and CL-Class models such as the W221, the integration between COMAND and other vehicle functions is even more complete, including access via COMAND to the HVAC system, seat controls, etc. On these cars, in contrast to most other Mercedes-Benz vehicles, COMAND is part of the standard specification rather than an optional extra. COMAND was introduced first exclusively on the flagship S-Class and CL-Class models. Later, it became available on other Mercedes cars too. Model history COMAND 2.5 Somewhat confusingly, COMAND 2.5 (not to be confused with the much later COMAND-APS NTG2.5) actually refers to the first generation of COMAND systems, introduced on the W220. The "2.5" label seems