This Recommendation describes the geometrical, mechanical, and transmission attributes of a single‑mode optical fibre which has the absolute value of the chromatic dispersion coefficient greater than some non-zero value throughout the wavelength range from 1530 nm to 1565 nm. This dispersion reduces the growth of nonlinear effects which are particularly deleterious in dense wavelength division multiplexing systems. This is the latest revision of a Recommendation that was first created in 1996. This revision creates a new category of the fibre having a reduced PMD link design value of 0.20 ps/km, in order to accommodate systems with higher bit rate/distance products than had been possible with prior revisions. This revision is intended to maintain the continuing commercial success of this fibre in the evolving world of high-performance optical transmission systems.