In pulsed telephone signaling (dialing,) the ratio, expressed in percent, of (a) the open-circuit (break) time to (b) the sum of the open- and closed-circuit times of a single dial pulse cycle. Note: For example, at a pulse rate of 10 per second, the pulse period is 100 milliseconds. If, during each pulse period, the equipment generating the dial pulses (e.g., a telephone set) presents an open circuit (high impedance) for 48 milliseconds, and a closed circuit (low impedance) for 52 milliseconds, the percent break is = 0. 48, or 48%.