ISO/TR 9721:1992

Applies to the description of refined nickel as well as of wrought and cast nickel and nickel alloys. The description for nickel alloys shall consist of the chemical symbols of the base element (Ni) and the alloying elements, followed preferably by whole numbers indicating their amount (the chemical symbols being listed in decreasing order according to the nominal alloy contents). Varieties of an alloy are specified by letter suffixes.