The scope of this Recommendation is to define a "degradation function" of the Optical Network Elements (DWDM line segment, PXC,OADM, etc) between points MPI-SMand MPI-RM(Figures6-1to 6-3) in terms of ASE, non-linear impairment, Chromatic Dispersion, PMD, etc, independently from the network architecture / structure / configuration that the system is deployed in.