(a) An employee or annuitant is eligible to enroll in an approved health benefit plan, in accordance with this part and the regulations of the board.
(b) Regulations may provide for the exclusion of employees on the basis of the nature, conditions, and type of their employment, including, but not limited to, short-term appointments, seasonal or intermittent employment, and employment of a like nature. However, no employee may be excluded solely on the basis of the hazardous nature of the employment.