65.—(1) A partial retirement option may only be exercised—
(a)by notice to the scheme manager in a form required by the scheme manager (“option notice”); and
(b)in the 3 months after P’s pensionable earnings are reduced, on a date agreed by the member and the scheme manager.
(2) An option notice must specify—
(a)whether P claims payment of—
(i)the whole of P’s accrued pensions; or
(ii)part only of P’s accrued pensions; and
(b)if P claims payment of part only—
(i)the descriptions of accrued pension for which payment is claimed; and
(ii)the proportion of each description of accrued pension for which payment is claimed (“option proportion”), which must comply with regulation 66.