If you are talking about what I think you are, it's called a CAN bus system. In simple terms its a way to transmit information and cut down on the wiring used in a car and amount of sensors needed. So lets take a coolant temperature sensor (CTS). The engine control module (ECM0, the transmission control module (TCM), the instrument cluster, and even the climate control module all need a coolant temperature reading. Instead of haviing a temp sensor for each module they use one sensor that sends its information to a module (in this case usually the ECM). THe ECM then takes the information and puts it out on the CAN bus. Any module that is looking for the information now can get it. With Audi's system they only use two wires for the CAN bus also which saves a lot of wiring on top of not needing all those extra sensors.