This part of ISO 8528 specifies the principal characteristics of a Reciprocating Internal Combustion (RIC) engine when used for alternating current (a.c.) generating set applications. It applies to RIC engines for 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), supplementary requirements may be necessary. The provisions of this part of ISO 8528 should be regarded as the basis for establishing any supplementary requirements. The terms which define the speed governing and speed characteristics of RIC engines are listed and explained where they apply specifically to the use of the engine for driving a.c. generators. For other reciprocating-type prime movers (e.g. steam engines), the provisions of this part of ISO 8528 should be used as a basis for establishing these requirements.