Bar code symbols, which contain invalid characters, are replaced with a checked box to visually indicate the error. The Code 39 mod 43 symbol structure is the same as Code 39, with an additional data security check character appended. The check character is the modulus 43 sum of all the character values in a given data string. It is designed to uniquely identify a product and its manufacturer. It is a fixed length, numeric, continuous symbology.
Every character has four elements.
The first digit is the number system character, the next five are the manufacturer number, the next five are the product number, and the last digit is the checksum character. U.P.C. E1 U.P.C. E0 stands for Universal Product Code Version E zero. U.P.C. E0 is a zero suppression form of U.P.C. A and is used by pre-arrangement with the Uniform Code Council. The ten digit input string consists of the five digit manufacturer's number and the five digit product code. U.P.C. E1 stands for Universal Product Code Version E1, it is also a numeric only and fixed length code, and is typically used for shelf labeling in the Retail environment.