A waveform that is generally constrained to lie between maximum and minimum voltage values. Between these extremes the waveform can only take on discrete and constant values of voltage for fixed periods of time. The waveform thus consists of a number of small step changes in voltage level, hence the term staircase. The height of each step will normally be made constant but may be variable, as may the period of time over which the waveform resides at a given voltage level.