A code in which "1s" are represented by one significant condition and "0s" are represented by another, with no neutral or rest condition, such as a zero amplitude in amplitude modulation (AM,) zero phase shift in phase-shift keying (PSK,) or mid-frequency in frequency-shift keying (FSK. ) Note: For a given data signaling rate, i.e., bit rate, the NRZ code requires only one-half the bandwidth required by the Manchester code.