This part of the IEC 61755 defines the dimensional limits of an optical interface for reference connectors necessary to meet specific requirements for fibre-to-fibre interconnection of non-angled polished multimode reference connectors with cylindrical ferrules intended to be used for attenuation measurements in the field or factory.

One grade of reference connector is defined in this document. The reference connector is terminated to selected IEC 60793‑2‑10:2015 A1a fibre. The geometrical dimensions and tolerances of the specified reference connector have been developed primarily to limit the variation in measured attenuation between multiple sets of two reference connectors, and therefore to limit the variation in measured attenuation between randomly chosen reference connectors when mated with connectors in the field or factory.