This part of IEC 62257, which is a technical specification, intends to describe the various rules to be applied to acceptance, operation, maintenance and replacement (AOMR) of decentralized rural electrification systems (DRES) which are designed to supply electric power for sites which are not connected to a large interconnected system, or a national grid, in order to meet basic needs. The majority of these sites are: isolated dwellings; village houses; community services (public lighting, pumping, health centers, places of worship or cultural activities, administrative buildings, etc.); economic activities (workshops, micro-industry, etc.). This technical specification proposes a methodology to achieve the best technical and economic conditions for acceptance, operation, maintenance and replacement of equipment and complete system life cycle. It does not substitute for technical manuals provided by manufacturers for each equipment. The complexity of the system and application will dictate the level of required AOMR documentation.