Syntax: @NOR(argumentlist)
argumentlist = any combination of numbers, cells, or ranges
@NOR returns 0 if any argument is 1; 1 if all arguments are 0; otherwise -1 (unknown).
Examples:
A1 = 1, B1 = 1, C1 = 0, D1 = 0, E1 = 1 and A2 = 24
@NOR(C1, D1) = 1
@NOR(A1..E1) = 0
@NOR(A1..A2) = -1