This Recommendation: ?C describes functional requirements and methods for optical fibre identification for the construction and maintenance of optical access networks; ?C deals with an optical fibre identification technique that functions by measuring certain optical characteristics. The optical fibre characteristics should comply with [ITU-T G.652] and [ITU-T G.657]@ which relate to single-mode optical fibres. It also considers the procedures and requirements for optical fibre identification@ including in-service fibre lines@ without interfering with optical communication signals in access networks; ?C describes the optical fibre identification technology that can be applied to different topologies of optical access networks.