The ‘EAN (International Article Number),’ equivalent to the UPC (Universal Product Code) of the United States, is an international standard number for identifying a material, which SAP allows you to assign (done in the ‘Eng./Design or Units of Measure’ screen) to the materials. The EAN is normally assigned to the manufacturer of a material. Made up of a prefix (to identify the country or company from where the material originates), article number, and a check digit (ensures correctness of an EAN number so that no incorrect entries are scanned or entered into the system).
A standards-compliant EAN can be generated here: http://barcoderobot.com/ean-13.html