The board may, in its discretion, deny the right to become a member to any class of employees who are serving on a temporary basis or whose compensation is set on any basis other than a per annum basis.

PL 1985, c. 801, §§5, 7 (NEW). PL 1991, c. 619, §13 (RPR). PL 1991, c. 619, §18 (AFF).