Under our current library system, we use 14 digit patron barcodes, and the 14th digit is determined as follows: 1. Multiply every other digit starting with the leftmost by 2 and total the digits of any multi-digit product. Sum the resulting digits. 2. Add remainder of digits (every other digit starting with the second from the left). 3. Add result of step 1 and step 2 and substract the rightmost digit of the sum from 10 to obtain the check digit. Example: Given: 2 1 1 1 2 0 0 0 6 9 8 1 3 C (C to be determined) (mult by 2) 4 2 4 0 12 16 6 sum = 26 step 1 1 1 0 0 9 1 sum = 12 step 2 Step 3: 26 + 12 ----- 38 10 - 8 = 2 = check digit. Back in January, I tried to modify the checkdigit subroutine of Input.pm to fit our circumstances, but I'm not sure that my code was completely successful. Would anyone want to take a shot at modifying this subroutine to fit our circumstances, since we would like to use our existing patron barcodes in Koha? Larry Currie -- Lawrence W. Currie User Services Librarian California Academy of Sciences Golden Gate Park San Francisco, CA 94118 lcurrie@calacademy.org (415) 750-7108 (415) 750-7106 fax http://www.calacademy.org/research/library/