In order to employ the same signal or variable as an input to more than one block or summing point, a take off point is used, as shown in Fig. 2.7. This permits the signal to proceed unaltered along several different paths to several destinations. A block with N inputs and M outputs is represented by a rectangle as shown in Fig. 2.8. The blocks representing the various components of a system are connected in a fashion which characterizes their functional relationship within the system. The arrows connecting one block with another represent the direction of flow of signals or information. In general, a block diagram consists of a specific configuration of four types of elements: blocks summing points, takeoff points, and arrows representing unidirectional signal flow.