ISO/IEC 15420:2009

Manufacturers of bar code equipment and users of bar code technology require publicly available standard symbology specifications to which they can refer when developing equipment and software.
ISO/IEC 15420:2009 specifies the requirements for the bar code symbology known as EAN/UPC. It specifies EAN/UPC symbology characteristics, data character encodation, dimensions, tolerances, decoding algorithms and parameters to be defined by applications. It specifies the Symbology Identifier prefix strings for EAN/UPC symbols.
Data content and the rules governing the use of this symbology are outside the scope of ISO/IEC 15420:2009; they are defined in the GS1 General Specifications.