Specifies basic performance requirements for impact attenuation, strength of the retention system and its attachment points. Includes peripheral vision clearance for lightweight protective helmets intended to mitigate the adverse effects of a blow to the head. Marking requirements are also proposed. Changes to this edition include amalgamation of the relevant requirements of AS 2063, Parts 1 and 2, a decrease in the recommended maximum mass for helmets, a requirement that the nominal mass of the helmet be marked on the helmet itself, a change in the recommended order in which tests are to be performed, and deletion of the requirement that the helmet manufacturer determines the helmet positioning index.