“…(1.1) f'(x;d) = p (d)-p_(d) = max <v,d> -max <w,d>, ve3f (x) we-af(x) where both of p^d) and p 2 (d) are sublinear operators, i.e., as the sum form of a pair of sublinear operator and superlinear operator, or as the difference form of two sublinear operators, [4], [8], [13]. This kind of structure of derivatives of quasidifferentiable function brings on that a quasidifferential of a quasidifferentiable function, called bidifferential also in [7], is not unique, but the quasidifferential class of equivalence of a quasidifferentiable function is unique.…”