The types of service creditable in the retirement system are:

1. (1) membership service;
2. (2) military service; and
3. (3) equivalent membership service.

Acts 1981, 67th Leg., p. 1876, ch. 453, Sec. 1, eff. Sept. 1, 1981. Renumbered from Vernon's Ann.Civ.St. Title 110B, Sec. 43.001 by Acts 1989, 71st Leg., ch. 179, Sec. 1, eff. Sept. 1, 1989.