Follett VERSION 6.00 - Manual (Page 697)

04/04 697 Appendix G The Bar Tender
Entering a check digit character in The Bar Tender will result in invalid barcodes.
Example: To define the barcode specifications for a Code 39 Mod 10 barcode with
a check digit, after selecting the symbology and check digit type, select the Data
Source tab:
Enter the beginning barcode
number in the Screen Data text
field without the check digit
(e.g., 318IU00000806 ), and
then set the Data Source.
The following is an example of a Code 39 Mod 43 barcode created by The Bar
Tender:
The Bar Tender automatically
calculates the check digit.
(Not shown actual size.)