Section 31-A - Participation by school district public librariesa. A school district public library, by resolution legally adopted by its board of trustees, may elect to become a participating employer in the retirement system, separate and distinct from the school district. Acceptance of the school district public library as a participating employer in the retirement system shall be mandatory with the comptroller.b. The officers and employees of such library shall be credited with such periods of prior service as shall be certified by the library for service rendered to it, or its predecessor, or the state, or in any other capacity approved by such library and the comptroller. Service for such library after the date on which it commences to participate in the retirement system shall be considered as member service. An officer or employee of such library who, as of the date he is so approved for membership in the retirement system, is already a member thereof, shall not have his total credit reduced by such approval. Any reserve held on account of any such officer or employee in the pension accumulation fund shall be used as an offset against the deficiency contribution payable thereafter by such library on account of such officer or employee for any prior service credit and any such previous credit.N.Y. Retire. and Soc. Sec. Law § 31-A