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Appendix K:
MSI/Plessey Specifications
Plessey
is a variable length numeric only bar code.
MSI
Bar Code is a variable length, numeric-only code with an automatically appended
Modulus 10 check digit. MSI is sometimes called
Modified Plessey Code
. If the user specifies an additional check digit, the MSI code can
be 14 digits long, otherwise it has a maximum length of 13 characters. This is how the MSI check digit(s) are calculated:
The MSI Mod 10 check digit is calculated as follows:
The example bar code data is:
82345
Form a number from the odd positions, starting in the units position.
835
Multiply the new number by 2
(835) x 2 = 1670
Add the digits of product
1 + 6 + 7 + 0 = 14
Add the even digits of the original number to the result in 3
2 + 4 + 14 = 20
Subtract the result from the next highest multiple of 10
20 - 20 = 0
New Check Digit
0
Data with check digit is:
823450
The MSI Mod 11 check digit is calculated as follows:
The example bar code data is:
943457842
Assign a checking factor to each number, starting with the units position of the number (in this example, the
2
) up to the
highest order position (the
9
). Use checking factors of:
2,3,4,5,6,7,2,3,4,5,6,7...
Multiply the checking factor with its assigned number and add the products:
4 + 12 + 32 + 35 + 30 + 28 + 6 + 12 + 36 = 195
Divide the sum by 11
195/11 = 17 remainder 8
Subtract remainder from 11
11 - 8 = 3
New Check Digit
3
(If the remainder is 10, no check digit is added.)
Data with check digit is:
943457823
