Publication 91 - Confirmation Services Technical Guide

Confirmation Services Technical Guide
calculation of the first 19 data digits and is placed in the 20th position to meet
Postal Service requirements.
USS Code 3 of 9
Code 3 of 9 requires a MOD 10 check sum in the 20th position in lieu of the
optional standard MOD 43 check sum to meet Postal Service requirements. It
should precede the stop character. The standard MOD 43 check sum must
be omitted; otherwise, it will cause an invalid barcode that cannot be read.
The algorithm for calculating the MOD 10 check digit appears at the end of
this appendix. This mandatory MOD 10 check digit is a data element that
must appear in human-readable form and is transmitted as data.
MOD 10 Check Digit Calculations
UCC/EAN Code 128
Digit positions are numbered from right to left for this calculation so that the
MOD 10 check-digit position counts as position 1. If concatenating the
routing code (AI of 420) with the PIC, calculate the MOD 10 check digit
beginning with position 1 up to and including the 91 AI. For example, the PIC
number 9101 1234 5678 9123 44 consists of the following:
AI = 91 (UCC/EAN Code 128 only)
Service Type Code = 01
Customer ID (D-U-N-S Number) = 123456789
4-digit Sequential Package ID = 1234
MOD 10 check digit = 4
The MOD 10 check digit is calculated using the following steps:
Step 1: Set up a two-row matrix, labeled 1 through 18, 1 being the most
significant position in the matrix (i.e., the right-most position). Starting from
the least significant position of the matrix (position 18), copy each digit of the
PIC all the way to position 2 (excluding the position of the check digit shown
in the example below by a “?”).
Position 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
PIC 9 1 0 1 1 2 3 4 5 6 7 8 9 1 2 3 4 ?
The dimension of the matrix (the number of cells) will vary depending on the
length of the Sequential Package ID. In this example, the Sequential
Package ID is 4 digits long (1234), requiring a matrix with a total of 18 cells
(including the cell for the check digit).
Consequently, the length of the matrix may vary from 16 cells (if the
Sequential Package ID is 2 digits long, which is very unlikely) to 22 digits (if
the Sequential Package ID is 8 digits long, which is the maximum allowable
length of the Sequential Package ID).
80 Publication 91, September 2002