EAN-13, based upon the UPC-A standard, was implemented by the International Article Numbering Association (EAN) in Europe. Now, the GS1 organization is responsible for the maintainance of barcode standards (refer to GS1 Homepage for more information.)
The EAN-13 barcode contains 13 digits, no letters or other characters. The first two or three digits represents the country. The leading zero actually signifies the USA, and UPC-A coding. The last digit is the “check digit”, the checksum. The check digit is calculated using the first twelve figures when the barcode is constructed. So, for the correct EAN-13 code, you should specify only the first 12 digits.