ISO 3166-1 alpha-3 codes are three-letter country codes in the ISO 3166-1 standard to represent countries and dependent territories . They are published by the International Organization for Standardization ( ISO ) as part of its ISO 3166 standard . ISO 3166-1 alpha-3 codes are three-letter country codes defined in ISO 3166-1 , part of the ISO 3166 standard published by the International Organization for Standardization ( ISO ) , to represent countries , dependent territories , and special areas of geographical interest .