How do barcodes in items found in shops work? And how are they registered?

Question

How do barcodes in items found in shops work? And how are they registered?

In: 5

Answer 1

The shops’ point-of-sale, inventory control, and stock-ordering systems are computerized and share the same data. Every product has a number and description in the system. The store usually gets all this data from the vendors/distributors the store buys from.

As for how they are registered, a central organization called GS1 standardizes barcode schemes and item numbering systems. GS1 delegates authority to regional organizations, who in turn register manufacturers.

Each manufacturer gets a number and an allotment of item numbers. The manufacturer decides how to assign the item numbers to products. Most retail products have a 13-digit number called a GTIN or EAN.

The actual numbering system is complicated, but it can be thought of as basically a leading digit to indicate the general region of the world, then some digits for the manufacturer, then some digits for the item, and then a “check digit” which is just calculated from the others.

This 13-digit number is encoded and printed on the item as a set of 2-dimensional, machine-readable bars. Human-readable digits are often printed below; they’re for manual keying-in if the scanner is broken.

The slightly older North American UPC standard was 12 digits, with no region code. Each digit is directly represented by a pattern of black and white lines. EAN expanded on this by making the last 6 digits be represented by one of 10 different sets of patterns; an EAN scanner can then infer the leading digit (the region code) from which pattern set was used. If the original UPC patterns were used, the region code was interpreted as zero.

Prior to the 2000s, a typical UPC scanner only knew about the original patterns and couldn’t read most EANs. But EAN is the standard nowadays; scanners know the patterns and always interpret the bars as a 13-digit EAN…even if they call it a UPC, and even if the barcode is printed in the old UPC-A format. UPC-A has some superficial differences to the standard EAN barcodes, like taller lines and a different layout of the human-readable part. For backward compatibility, some modern scanners can be programmed to report only 12 digits if the leading digit is zero.

13 digits is a lot, but not enough for some products, like books, so these may have supplemental numbers encoded in a mini barcode that comes after the main one.