RZ (return-to-zero) refers to a form of digital data transmission in which the binary low and high states, represented by numerals 0 and 1, are transmitted by voltage pulses having certain characteristics. The signal state is determined by the voltage during the first half of each data binary digit. The signal returns to a resting state (called zero) during the second half of each bit. The resting state is usually zero volts, although it does not have to be. in positive-logic RZ, the low state is represented by the more negative or less positive voltage, and the high state is represented by the less negative or more positive voltage. Examples are: Logic 0 = 0 volts for 1 bit.Logic 1 = +5 volts for 1/2 bit, then 0 volts for 1/2 bit. Logic 0 = -4 volts for 1/2 bit, then 0 volts for 1/2 bit. Logic 1 = 0 volts for 1 bit. in negative-logic RZ, the low state is represented by the more positive or less negative voltage, and the high state is represented by the less positive or more negative voltage. Examples are: Logic 0 = +5 volts for 1/2 bit, then 0 volts for 1/2 bit. Logic 1 = 0 volts for 1 bit; Logic 0 = 0 volts for 1 bit; Logic 1 = -4 volts for 1/2 bit, then 0 volts for 1/2 bit