We make some local products. To sell those in the market, we generate local barcodes for them.
EAN13 is the most used barcode in our region, that's why I developed my system to generate the first 12 digits of the barcode from some item information like number and date of release. The 13th digit is the key and it generates using it's standard algorithm which is available and known.
I have faced a problem with some hyper markets (like Carrefour) that their systems didn't accept some of my locally generated barcodes.
Are there any rules for those barcodes which let Carrefour to reject my generated ones?