(1)Subject to subsection (2) and section 10(3), where the instrument by which any disposition is made so provides, the perpetuity period applicable to the disposition under the rule against perpetuities, instead of being of any other duration, shall be of a duration equal to such number of years not exceeding eighty as is specified in that behalf in the instrument.
(2)Subsection (1) shall not have effect where the disposition is made in exercise of a special power of appointment, but where a period is specified under that subsection in the instrument creating such a power the period shall apply in relation to any disposition under the power as it applies in relation to the power itself.