This Guideline applies to reciprocating internal combustion (RIC) engines in accordance with DIN ISO 3046-1@ hereinafter calied reciprocating internal combustion (RIC) engines@ working after the two- or four-cycle principle with dieselengine combustion. Such kind of reciprocating internal combustion (RIC) engines are used@ for example@ - in industry (e.g. as stationary engines) and - to drive equipment@ machines@ watercraft@ railbound and road vehicles. Purpose This Guideline describes the State of the art of the abovementioned engines with respect to their airborne sound radiation. The indicated noise emission values have been determined in accordance with a standardised measurement method. The characteristic emission values defined in clause 4 and presented in clause 5 are used to describe the noise emission. Furthermore@ Annex A of this Guideline gives Information regarding methods for the reduction of airborne sound and structure-borne sound of reciprocating internal combustion (RIC) engines. This Guideline presents an aid to its users (designers@ manufacturers@ operators and institutions dealing with the evalua? tion@ checking or monitoring of the noise emission of recipro? cating internal combustion [RIC] engines) in assessing the acoustic aspects.