Used with permission. This Tutorial was created by George Laurer, the creator of the U.P.C. Barcode Symbol. Copyright ID History Museum 2007-2012 http://www.idhistory.com
Understanding the construction of the U.P.C. symbol starts with an understanding of the character sets used by the U.P.C. In order to encode the ten decimal digits in bars, a character structure consisting of seven modules of equal width is used for each character. Each charter must start with a white space and end with a black bar. Also each character must have two white spaces and two black spaces or bars. Figure #1 depicts a typical character.
There are twenty bar space patterns that satisfy the rules stated. Using the notation that a “0” represents a white module and a “1” represents black module, the twenty patterns are listed below along with the arbitrary digit assignments used in the U.P.C. code.
Odd Parity Patterns
Even Parity Patterns
Guard bar pattern
Version E end pattern