To make sense of the 8 data bytes, the controller will decode the data into signal such as engine RPM, fuel level, or brake pedal position. Each signal has a start bit and end bit, which are used to select the correct bits out of the 8 bytes. No signal information is transmitted over the bus. Instead all controllers must agree on the layout of messages and signals beforehand. Below is the table of signals, and the graphical layout of a sample message.