As used in this article, the following terms shall have the meanings indicated:
Deferred Retirement Option Plan.
A separate interest-bearing subsidiary DROP participant account shall be established for each DROP participant. While a retired member is employed as a DROP participant, the member's monthly, normal retirement benefit and interest thereon shall be credited to the DROP participant's subsidiary DROP participant account. The interest shall be compounded and credited monthly at the actual rate earned by the DROP participant account that shall not be less than 0% nor more than 4 1/2%.