Applies to optical amplifiers (OAs) and optically amplified, elementary sub-systems for terrestrial applications, using active fibres (optical fibre amplifiers, OFAs), containing rare-earth dopants, which are commercially available. The black box approach is used in this IEC standard. The black box approach is adopted in order to give product specifications which are independent of OA implementation details. For reliability qualification purposes, some information about the internal components is needed; these internal parts are themselves treated as black boxes. This standard gives requirements for the evaluation of OA reliability by combining the reliability of such internal black boxes. Experts in IEC SC 86C (Fibre optic systems and active devices) explain that "this is the first international standard devoted to reliability testing of optical fibre amplifiers. This publication is intended for engineers in the fibre optic communications industry in particular, but also for suppliers of optical fibre amplifiers and their immediate customers.. In addition, fulfilling the testing requirements of these optical amplifiers and their internal components gives some assurance that the network element will perform in field application for the environments stated there."