Appendix G Operator’s Guide
RJS, Minneapolis, MN 002-5572
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Appendix G (ANSI Decodability)
ANSI Decodability Calculations
There is a specified method for calculating decodability for each symbol. But the method is generally the same for all.
Each element width in a barcode symbol should be consistent across the symbol.
Code 39
In the case of Code 39, two element widths are needed to produce a symbol.
For optimum scanning, each narrow element, whether a bar or space, should have the same width dimension.
And each wide element should have the same width dimension.
Simply stated, the Decodability grade indicates the amount of tolerance remaining in the width of the most deviant
element in the symbol. The more tolerance remaining, the higher the grade.
The grade is displayed showing both a calculated numeric and a letter grade, i.g. “D/bility .90 A.”
UPC/EAN
In the case of UPC and EAN symbols, the grade is calculated per a proposed guideline draft dated Septem-
ber 4, 1990 issued by the USS.
Decodability Grade Conversions
>= .62 = A
>= .50 = B
>= .37 = C
>= .25 = D
< .25 = F
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