99.25. Notwithstanding section 56, a pension shall be granted to every officer who
(1) has, in years of age and years of service, a combined total of 80 or more, if he is at least 50 years of age;
(2) has attained 60 years of age;
(3) is no longer able to perform his regular functions because of physical or mental disability;
(4) has at least 10 years of service and is 50 years of age or over.
The officer is required to be a member of the plan at the time he retires under any of the criteria listed above.