1975IEC 60255-1-00:1975 Electrical relays. Part 1 : All-or-nothing electrical relays
IEC 60255-1-00:1975 Electrical relays. Part 1 : All-or-nothing electrical relays was changed to IEC 61810-1:1998 Electromechanical non-specified time all-or-nothing relays - Part 1: General requirements.