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Appendix G

Interleaved 2 of 5 Code
Interleaved 2 of 5 Code is a numeric-only, even-number-of-digits bar code. It is
widely used in warehouse and industrial applications. A combination of five
elements, two wide and three narrow represent each character. Odd-number
position digits are encoded in the bars, even-number positions in the spaces.
Interleaved 2 of 5 Code is so susceptible to partial scans being
interpreted as valid reads that we recommend at least one of the
following safeguards:
• Use one length of I 2 of 5 code. Using one length of data allows
you to tell the RF Laser Reader to look for one length of I 2 of 5
code only. By default, the RF Laser Reader is set to look for a 6
digit I 2 of 5 code but you can set the length to something different
using the RF Laser Reader Setup Menu. Setting the length to 00
digits allows variable length bar codes scanning but also
dramatically increases your chance of a mis-read.
• Use a check digit. Worth Data’s LabelRIGHT printing program
automatically calculates and prints a check digit upon request using
the method below:

Interleaved 2 of 5 Mod 10 check digit calculation

1. Assume that the bar code data is 1987.
2. Starting with the least significant digit (in this case, a 7), label the
digits alternatively even and odd.
7 - even
8 - odd
9 - even
1 – odd
3. Take the sum of the odd digits:
8 + 1 = 9
4. Multiply the sum of the even digits by 3:
(7 + 9) x 3 = 48
5. Add the results of steps 3 and 4:
9 + 48 = 57
123456