Tally Genicom Matrix Printer - Manual (Page 396)

Add-On 2 3 numbers are transmitted: check number (c) and 2 informations (n).
The check number results from the remaining integer value of modul (4).
Example 1
Information 0 0 4
Remainder (0) 0
Example 2
Information 2 0 6
Remainder (2) 2
Example 3
Information 3 9 9
Remainder (3) 3
Example 4
Information 1 0 9
Remainder (1) 1
The check number always lies between "0" and "3"; it is not printed in the HRI line.
Barcode Printing 41