Syntax: @NOT(X)
X = a numeric value
@NOT returns 1 if X=0; 0 if X=1; otherwise -1 (unknown).
Examples:
A1 = 1, B1 = 1, C1 = 0, D1 = 0, E1 = 1 and A2 = 24
@NOT(A1) = 0
@NOT(A2) = -1
@NOT(C1) = 1