Relates to individual fibre optic adaptors such as: -adaptors for connecting a plug connector to an identical type of plug connector; -adaptors for connecting one type of plug connector to a different type of plug connector; -adaptors for connecting a fibre optic connector to their optical devices such as LEDs, switches, etc. The specification includes: -adaptor requirements; -quality assessment procedures. The specific technical changes from the previous edition include the updating of the classification, specification system and standardization system.