Document designGeneric MICR Fundamentals Guide 4-19MICR character spacing requirementsReader sorters have timing limits that prevent them fromhandling extreme variations in character spacing. The averagespacing requirement for MICR characters is 0.125 inch/6.4 mmper character (8 characters per inch).The MICR specifications have a tolerance on the 0.125 inch/6.4mm spacing requirement of ± 0.010 inch/.3 mm. Specificationsalso state that the accumulated error must not exceed fieldboundaries, shown in table 4-1. MICR characters are rightjustified and the numbers are read from right to left. This meansthat you might need to pad the MICR line with leading blanks sothat the numbers start in the correct position.Character spacing algorithm for 300 dpiMICR printing systems print at 600 or 300 dots per inch. At 600dpi, there are no issues with character spacing. 600 dpi can bedivided evenly by 8 characters per inch, resulting in 75 dots percharacter.However, 300 dpi, when divided by 8 characters per inch, resultsin 37.5 dots per character. The system cannot print half a dot, soit cannot print each character at exactly 8 characters per inch.You can achieve an average of 37.5 dots per character by usinga proportional spaced font with a spacing algorithm that places aspace of one dot after every second character. In other words,two characters of 37 dots are printed, followed by a one-dotspace, then the sequence is repeated. This algorithm is usedextensively in high volume printing installations.Fixed pitch and proportional font spacingThe relationship between the input character and the outputcharacter or space is shown for proportional spaced fonts intable 4-3, and for fixed pitch fonts in table 4-4.NOTE: The relationship between the input character and theoutput character may differ slightly from these tables for someXerox MICR products. These differences are primarily found withthe revision control character (?) and the special symbols.
