This Recommendation is concerned with the characteristics of monitoring systems for optical fibre submarine cable systems. It covers the aspects relating to functional architecture@ the characteristics of monitoring equipment and the parameters for monitoring. The purpose of this Recommendation is to help users (e.g.@ submarine network operators) in their operation and maintenance@ diagnostics and deployment of optical fibre submarine cable systems. Detailed information is given for: 1) monitoring system architecture 2) reference points 3) parameters for monitoring