ISO 4254-12:2012, where used with ISO 4254-1, specifies the safety requirements and their verification for the design and construction of rotary disc mowers, rotary drum mowers, as used for forage crop harvesting in agriculture only, and flail mowers with a horizontal axis for use in agriculture only, that are mounted, semi-mounted, trailed or self-propelled. It describes methods for the elimination or reduction of hazards arising from the intended use and reasonably foreseeable misuse of these machines by one person (the operator) in the course of normal operation and service. In addition, it specifies the type of information on safe working practices to be provided by the manufacturer.

Flail mowers with a horizontal axis that can be opened at the rear only for maintenance reasons are included.

ISO 4254-12:2012 is also applicable to mowers equipped with a conditioning device and only to mowers intended to work at ground level.

ISO 4254-12:2012, taken together with ISO 4254-1, deals with all the significant hazards, hazardous situations and events (with the exception of noise and vibrations) relevant to rotary disc mowers, rotary drum mowers and flail mowers, when they are used as intended and under the conditions of misuse that are reasonably foreseeable by the manufacturer.

It is not applicable to flail mowers that have the rear part which can be opened for particular field use operations, mowers with an articulated arm, mowers with one or more vertical axes designed for mulching, pedestrian-controlled motor mowers, lawn mowers, inter-row mowing units and machines specifically designed for highway and road maintenance.