Specifies a symbol recommended for use only to signify the potential or actual presence of ionizing radiation and to identify devices, objects, materials or combinations of materials which emit such radiation. For this standard's purpose, ionizing radiation means X - and gamma rays, high speed electrons, alpha and beta particles, protons, neutrons and other ionizing particles; but not sound or radio waves, or visible, ultra-violet, or infra-red light. Does not specify the radiation levels at which the symbols are to be used.

BS 3510(1962) : LATEST

ISO 361 : 1975(R2015) - Identical