This Recommendation describes the transmission related attributes of single-mode optical fibre and cable with chromatic dispersion (absolute value) that is greater than some non-zero value throughout the wavelength range of anticipated use within the 1550 nm window. This chromatic dispersion suppresses the growth of four-wave mixing, a non-linear effect that can be particularly deleterious in dense wavelength division multiplexing (DWDM) systems. These fibres are optimized for use in the wavelength range from 1530 nm to 1565 nm. Some provisions are made to support transmission at higher wavelengths - up to 16xx nm, with xx less than or equal to 25 nm. Extensions are possible, in the future, to wavelengths lower than 1530 nm (to be determined). Definitions and test methods are contained in a separate ITU-T G.650. Tables of recommended values for different subcategories of this fibre type are provided to allow ease of reference with regard to the types of systems that are supported. Subcategories described in the tables may differ for technological aspects or for the intended application. Allowed ranges are recommended for both fibre and cable attributes. Information for link attributes and system design is found in Appendix I.