N.Y. Est. Powers & Trusts Law § 10-3.4

§ 10-3.4 Classification of powers of appointment as to duty to exercise;\n imperative and discretionary\n (a) A power of appointment is either imperative or discretionary.\n (b) A power of appointment is imperative if the instrument creating it\nimposes on the donee a duty to exercise it, and it may be imperative\neven though it is exclusive.\n (c) A power of appointment is discretionary if the donee is authorized\nto exercise or not to exercise it.\n