This Recommendation describes the geometrical, mechanical and transmission attributes of a singlemode optical fibre and cable which has the zero-dispersion wavelength around 1300 nm wavelength and which is loss-minimized and cut-off wavelength shifted at around the 1550 nm wavelength region. This is the latest revision of the Recommendation that was first created in 1988. This revision changes the notation of PMD in order to make it consistent with that of ITU-T recommendation G.652.creates new categories 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.