Defines various classifications for the applications, ratings and performance which arise out of the combination of generating sets consisting of an RIC engine, a.c.generator, controlgear, switchgear and auxiliary equipment. Applies to a.c. generating sets for land and marine use, excluding generating sets used on aircraft or to propel land vehicles and locomotives. For some specific applications (e.g. essential hospital supplies, high-rise buildings, etc.) supplementary requirements may be necessary.