The placement of the vertical edges must occur

The placement of the vertical edges must occur in increments of 0.013 inches from the first right-hand edge. There are five characters that have two positive and two negative peaks similar to the character 0 and also appear in a positive-negative-positive-negative format. They are 0, 2, 4, 5, and the transit character, which are differentiated from one another by the horizontal location of the peaks in the waveforms. The peaks do require different amplitudes, but ANSI standards allow them to vary from 50% to 200% of the nominal amplitudes (Canadian standards allow them to vary from 80% to 200% of the nominal amplitudes). This is why the placement of the waveform is so important and why the characters are shaped unusually.
Signal level can vary based on a number of factors. The amount of iron oxide (concentration) that is present in the character will affect the signal level. This is a function not only of the toner itself, but also of how it is laid on the paper and the pile height, which can be controlled by numerous other cartridge components (i.e., "hot" OPCs).
The taller the vertical edge of the character, the taller the peak (either positive or negative). A vertical edge that is not regular and/or not vertical will result in a reduction in the amplitude of the peak and will flatten the peak out.