This part of IEC 61754 defines the standard interface dimensions for the type M12-FO family of connectors. Fibre optic interconnecting devices and passive components are often used in industrial environments for factories and process automation, such as control units, utility rooms on the supply level or in cabinets. The particular environmental conditions such as temperature, dust, humidity, vibrations, chemical, etcetera, require more robust components for industrial use than they can be found in standard environments. Multiple designs for machines and equipment require solutions with different fibre types. The standard contains the dimensions and tolerances of the mentioned connector family and specifies the mechanical interoperability of identical connectors, couplings and sockets. Thus, the standard provides manufacturers and users with investment security and provides test laboratories and manufacturers with defined information regarding the structure and interfaces. The responsible committee involved is DKE/UK 412.7 "LWL-Verbindungstechnik und passive optische Komponenten" ("Fibre optic interconnecting devices and passive optical components") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.