This part of IEC 61754 defines the standard interface dimensions for the type LF3 family of connectors. 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 test laboratories and manufacturers with detailed information on structure and interfaces. The standard describes various connector variants for quartz glass fibres. The products of the IEC 61754 standard series are applied together with the standards of the IEC 61755 (Optical interface) and IEC 61753 (performance standard) series and tested by the standards of the IEC 61300 (Basic test and measurement procedures) series. The responsible committee 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.