ISO/IEC 646, is an ISO/IEC standard in the field of character encoding. It is equivalent to the ECMA standard ECMA-6 and developed in cooperation with ASCII at least since 1964. The first version of ECMA-6 had been published in 1965, based on work the ECMA's Technical Committee TC1 had carried out since December 1960. The first edition of ISO/IEC 646 was published in 1973, and the most recent, third, edition in 1991.