This Recommendation provides physical layer specifications for dense wavelength division multiplexing (DWDM) applications in point-to-point repeaterless optical fibre submarine cable systems. The goal is to enable longitudinally compatible applications. The primary purpose is to enable multiple vendors to provide transmission equipment for submarine fibre links that are compliant with this Recommendation. This Recommendation includes a generic reference model for the physical layer applications. The specifications take into account parameters such as maximum attenuation@ fibre types@ wavelength ranges@ maximum chromatic dispersion@ minimum local chromatic dispersion coefficient@ maximum differential group delay@ and minimum effective area. This Recommendation focuses on repeaterless optical fibre submarine cable systems without remotely pumped optical amplifiers. This Recommendation presumes that the optical tributary signals transported within optical channels are digital.