Another 2 cents worth: See ANSI Standards N2.1-1989 (Radiation Symbol) and N12.1-1989 (Fissile Material Symbol) for definition. H. Dean Chaney, CHP - USNRC, Region IV/WCFO hdc@nrc.gov ddchaney@castles.com The views put forth above are my own and do not necessarily reflect the beliefs or policies of the USNRC or any other governmental entity.