This Recommendation describes a dispersion-shifted@ single-mode optical fibre and cable which has a nominal zero-dispersion wavelength close to 1550 nm@ and a dispersion coefficient which is monotonically increasing with wavelength. This fibre is optimized for use in the 1550 nm region@ but may also be used at around 1310 nm subject to the constraints outlined in this Recommendation. Some provisions are made to support transmission at higher wavelengths up to 1625 nm and lower wavelengths down to 1460 nm. Chromatic dispersion coefficient values at these wavelengths may be specified to support coarse wavelength division multiplexing (CWDM) systems that do not have significant impairment due to non-linear effects. The geometrical@ optical@ transmission and mechanical parameters are described below in three categories of attributes: ?C fibre attributes are those attributes that are retained throughout cabling and installation; ?C cable attributes that are recommended for cables as they are delivered; ?C link attributes that are characteristics of concatenated cables@ describing estimation method of system interface parameters based on measurements@ modelling@ or other considerations. Information for link attribute and system design are in Appendix I. This Recommendation@ and the different performance categories found in the tables of clause 7@ is intended to support the following related system Recommendations: ? [b-ITU-T G.957]; ? [b-ITU-T G.691]; ? [b-ITU-T G.692]; ? [b-ITU-T G.693]; ? [b-ITU-T G.959.1]; ? [b-ITU-T G.977]; ? [b-ITU-T G.695]; ? [b-ITU-T G.698.1]. The meaning of the terms used in this Recommendation and the guidelines to be followed in the measurements to verify the various characteristics are given in [ITU-T G.650.1] and [ITU-T G.650.2]. The characteristic of this fibre@ including the definitions of the relevant parameters@ their test methods and relevant values@ will be refined as studies and experience progress.