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Appendix B: Code 128 Information
The 128 bar code is divided into 3 character sets (Code A,
Code B, and Code C). Depending on the character set used,
the same bar pattern can be one of three characters. Table 1,
at the end of this appendix, lists the characters in each
character set.
Code A
contains upper case letters (A-Z), special
characters, and control characters. Code A does
not have lower case letters.
Code B
contains upper and lower case alphanumeric
characters and special characters. Code B does
not have control characters.
Code C
character set contains pairs of numbers. In code
C, each bar pattern represents a pair of numbers,
ranging from 00 to 99.
When the data contains at least four numbers in a row, 128
switches to code C, then prints one bar pattern for each pair of
numbers. This doubles the numeric data per inch.
Therefore, it may be better to pad numeric data with a zero if it
has an odd number of characters. The bar codes below show
the difference between an odd number of numeric characters
and an even number of numeric characters. Do this only if
your system can ignore leading zeros.
Data = 1234567
Data = 01234567
Bar Code 1
Bar Code 2
B-1
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