Appendix B: Code 128 Information
The 128 bar code is divided into 3 ch aracter sets (Code A,
Code B, and Code C). Dependi ng on the character set used,
the same bar pattern can be one o f three characters. Table 1,
at the end of this appendix, l ists 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 prin ts one bar pattern for each pa ir of
numbers. This doubles the numeri c data per inch.
Therefore, it may be better to pad numeric data with a zero if it
has an odd number of character s. 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 z eros.
Bar Code 1
Data = 1234567
Bar Code 2
Data = 01234567
Appendix B:
Code 128 Information
B-1