AmberPOS will generate a local sequential UPC number that starts with a 4, if there is no proper UPC number already linked to the product and a UPC barcode is printed.
Please check the criteria for a proper UPC code here: http://www.azalea.com/white-papers/upc-barcode-check-digit/
Here is an example of what an AmberPOS generated UPC number would look like:
1. A NON UPC number is entered under the "Lookup/UPC" field
2. When printing a barcode label, AmberPOS will create the local sequential UPC number.
3. This number will be added under the "Lookup/UPC" field.