This part of IEC 63267 defines certain dimensional limits of a flat PC rectangular polyphenylene sulphide (PPS) ferrule optical interface in order to meet specific longitudinal offset requirements for fibre-to-fibre interconnection. Ferrules made from the material specified in this PAS are suitable for use in categories C, U, E, and O as defined in IEC 61753‑1.

Ferrule interface dimensions and features are contained in IEC 61754 (all parts), which deals with fibre optic connector interfaces.