Section 384-e of the Retirement and Social Security Law, which was enacted pursuant to chapter 453 of the Laws of 1988, provides a benefit improvement which may be adopted by employers who have previously adopted the section 384-d optional twenty year plan. The section 384-e benefit improvement provides an additional pension component equal to one sixtieth of final average salary; provided, however, that the total allowance payable shall not exceed three quarters of the member's final average salary. An employer's adoption of the section 384-e benefit improvement entitles all individuals who are in their employ and enrolled in the 384-d plan during the “coverage period” to elect the section 384-e improvement. All such employees may elect the benefit improvement by filing an election with the Comptroller at any time during their current employment with that employer and while enrolled in the section 384-d plan. The employer establishes a “coverage period” by so providing in the election to provide the benefit, which the employer must file with the Comptroller. This Part shall provide the procedure under which employers may file an election to provide the section 384-e benefit improvement and the guidelines with respect for establishing a “coverage period.”