This supplement describes design considerations for repeatered, repeaterless and optically amplified systems supporting SDH and OTN signals in optical submarine cable systems. In particular, this supplement focuses on the specific matters relevant to the optical fibre submarine cable systems.

This supplement also describes a common way of thinking of the requirements for designing the optical fibre submarine cable systems and aims of consolidating and expanding on materials related to several Recommendations, including G.971, G.972, G.973, G.974, G.975, G.975.1, G.976 and G.977.