The EAN symbology
The barcode symbology most commonly seen in Europe and most of the rest of the world is EAN. It is a numeric-only bar code system used for identification of retail products. Unique numbers are allocated to each separate retail product, not just by product brand but by variation (weight, colour, flavour, etc..). Also separate numbers are required when the product changes (except when the price changes).
The EAN barcode symbolgy can encode GTIN-13 numbers (in EAN-13 barcodes) and GTIN-8 numbers (EAN-8 barcodes).
The 13 digit code is more common. The 8 digit code is generally used where space is restricted.
There are two other variants of EAN which have supplementary "add-on" codes: 13+2 and 13+5:
Although not often used in practice, the add-on codes are available for encoding supplementary information.
The EAN symbology is intended as a world wide standard (although some countries use other systems), therefore, no two retail products may have the same number. To ease the administration of number allocation, Each country using EAN has a country identifier at the start of the barcode. For the U.K. the digits 50 identify U.K. manufacture. Other countries have 2 or 3 digit prefixes, (93 for Australia, 773 for Uruguay, etc..)
The rest of the EAN13 code is divided into the Manufacturer Number, the Item Reference Number and the check digit.
GS1 offices in each country assign Manufacturer Numbers. The Item Reference Number is decided by the manufacturers, who are free allocate the available digits as they wish.
Although the UPC system preceded the use of EAN codes, EAN was made retrospectively compatible. In theory all scanners designed to read UPC should also read EAN, and vice-versa. In practice, all EAN scanners will read UPC but some scanners sold in the USA could not read EAN. Such scanners are no longer being sold and the systems are becoming compatible.
Like UPC, the EAN symbol is described by magnification, the allowable limits being 80% to 200%. For each magnification there is a recommended (or nominal) height. This figure is recommended to ensure symbol readability when read by a multi-directional scanner, therefore any reduction in height (truncation) should only be attempted if absolutely necessary.
In common with most other bar code implementations EAN8 and EAN13 have a check digit which is the last number on the right. It is used to check for an error in scanning or data entry. The most common error found with the transcribing or keying of data is that of transposition (reversing the order of two digits). Therefore, the following system is used:
1. Starting from the right of the number and excluding the check digit, add each alternate digit.
2. Multiply the result of 1. by 3
3. Add all remaining digits.
4. Add result 2. to result 3.
5. The check digit is the smallest number which when added to the result of step 4. produces an exact multiple of 10.
For example, the check digit for the number 401234567890 is calculated as follows:
20 x 3 = 60
9+7+5+3+1+4 = 29
60 + 29 = 89
89 + 1 = 90 - therefore the check digit is 1.
In both the UPC-A and EAN13 bar code symbologies 12 digits are encoded by the bar/space pattern above the human readable character. The major difference with EAN13 is that the 13th character (the one to the left of the code) is encoded by the variable parity of the left hand side of the code. The EAN number system uses 3 differing character sets (A,B and C). In each character set the bar/space pattern for a given digit is different. The right half of the code uses only character set C whereas the left half can use a mixture of sets A and B. It is the pattern of the mixture which determines the 13th character. For example if the left hand half of the code used ABBAAB then the 13th digit would be 5.
In common with other symbologies, EAN has a set of allowed tolerances for the quality of the printed code. These measurements relate to the maximum variation in the width of a single bar or space and vary according to magnification factor:
As the above table shows, the tolerances allowed reduce rapidly for magnification factors below 100%. For this reason the final print method should be considered carefully when choosing a magnification factor. For example, some printing presses are too variable to consistently print small (e.g. 80%) EAN codes.