UPC Code Rules

UPC-A barcodes have 12 digits total 

S2K Rules: 

1.  Always Drop the last digit (on the far right) no matter what number it is

2.  Drop the first digit (on the far left) ONLY if the number is a Zero (0)

3.  The inner 10 digits are ALWAYS included.

UPC-E barcodes have 8 digits total

S2K Rules:

1.  Include all 8 digits in S2K

2.  Press the UPCe to UPCa expansion button.