(1) Kind of Membership. — (a) Membership in a system shall consist of two kinds as follows:—

1. (i) Member in Service.— Any member who is regularly employed in the performance of his duties, except a member retired for disability who upon partial recovery is restored to active service as provided for in paragraph (2) (a) of section eight. Any member in service shall continue as such during any period of authorized leave of absence with pay or during any period of authorized leave of absence without pay if such leave is due to his mental or physical incapacity for duty or if such authorized leave of absence without pay is for not more than one year or is to permit such member to perform his duties as a member of a retirement board. In any event the status of a member in service shall continue as such until his death or until his prior separation from the service becomes effective by reason of his retirement, resignation, failure of re-election or reappointment, removal or discharge from his office or position, or by reason of an authorized leave of absence without pay other than as provided for in this clause. Any member in service shall have full voting powers in the system as provided for in section twenty of this chapter and in section sixteen of chapter fifteen.
2. (ii) Member Inactive. — Any member in service who has been retired and who is receiving a retirement allowance, any member in service whose employment has been terminated and who may be entitled to any present or potential retirement allowance or to a return of his accumulated total deductions under the provisions of sections one to twenty-eight inclusive, or any member in service who is on an authorized leave of absence without pay other than as provided for in clause (i) of this paragraph. Any member in-active shall have full voting rights as provided for in section twenty of this chapter and in section sixteen of chapter fifteen.
3. (b) A beneficiary shall not be deemed to be a member of the system nor shall he have any voting rights therein.
4. (c) No description of a person having any rights or privileges under the provisions of sections one to twenty-eight inclusive, such as member in service, member inactive, beneficiary or otherwise, shall serve to deprive him of any such rights or privileges. A member shall retain his membership in the system so long as he is living and entitled to any present or potential benefit therein.

(2) Eligibility for Membership. — (a) Membership in a system as a member in service as defined in clause (i) of paragraph (1) (a) of this section shall comprise the following persons:—

1. (i) Any employee who is a present member in service, including any employee for whom regular deductions are being made whether or not he was classified as a member under provisions of earlier laws;
2. (ii) Any employee in active service who is not now a member but who, while under the maximum age for the group in which he would be classified, hereafter files with the board on a prescribed form a written application for membership, subject to the provisions of sections one to twenty-eight inclusive; provided, that during his present period of service he had previously been eligible for membership;
3. (iii) Any person who hereafter resigns, transfers or is promoted from a position in the service under which he had inchoate rights to a non-contributory pension under this chapter or under corresponding provisions of earlier laws or of any other general or special law, to accept a position subject to the provisions of sections one to twenty-eight inclusive, if at the time of such resignation, transfer or promotion he is under the maximum age for the group in which he would be classified;
4. (iv) Any person, except as specifically otherwise provided for in sections one to twenty-eight, inclusive, who enters or re-enters the service as an employee of the commonwealth, a teacher as defined in section one, or an employee of any political subdivision of the commonwealth for which a system established under the provisions of such sections, or under corresponding provisions of earlier laws, is in operation on the date when he becomes an employee; provided, that any such person who becomes regularly employed, as determined by the board as provided for in paragraph (d) of this subdivision, on a part-time, provisional, temporary, temporary provisional, seasonal or intermittent basis, shall become a member in service, if he is to be classified in Group 1, upon the completion of six calendar months of service, and any other such person shall become a member in service upon his entry into service; and provided, further, that a physician or dentist who is employed as an intern in a municipal hospital shall not become a member unless he files a written application for membership within ninety days of his appointment.
5. (v) Any state official as defined in section one hereafter appointed to office who files with the board on a prescribed form a written application for membership within ninety days after the date of assuming the duties of his position; provided, that a member becoming a state official shall retain his membership and a state official who is a member shall remain a member upon his reappointment or upon his appointment or election to any other position which would otherwise entitle him to membership;
6. (vi) Any person hereafter elected by popular vote to a state, county or municipal office or position who files with the board on a prescribed form a written application for membership within ninety days after the date of assuming office; provided, that a member becoming an elected official shall retain his membership and an elected official who is a member shall remain a member upon his re-election or upon his election or appointment to any other position which would otherwise entitle him to membership;
7. (vii) Any person who hereafter is reinstated to or who re-enters the active service of the governmental unit in which he was formerly employed as provided for in subdivision (6) of this section; provided, that any such person who fails to pay into the annuity savings fund of the system the amount of the accumulated regular deductions, if any, withdrawn by him together with buyback interest to the date of reemployment, or fails to make provision for payment thereof, under the terms set forth in such subdivision, shall be considered as a person first entering the employ of such governmental unit and shall become a member in service only under the conditions applicable to such person as set forth in this section;
8. (viii) Any employee who enters the active service of any governmental unit and who was a member of any system established under the provisions of sections one to twenty-eight inclusive, or under corresponding provisions of earlier laws or of any special law, and who hereafter transfers or re-establishes his membership as provided for in subdivision (8) of this section to or in the system which pertains to such governmental unit; provided, that any such employee who fails to transfer or re-establish his membership as so provided for shall be considered as a person first entering the employ of such governmental unit and shall become a member in service only under the conditions applicable to such person as set forth in this section; and
9. (ix) Any member retired for disability who upon recovery hereafter is restored to full active service as provided for in paragraph (2) (b) of section eight.
10. (x) Any employee as defined in section one.

11. (xi) Any employee, any part or all of whose salary, wages or other compensation is derived from federal grants made to the commonwealth or to any political subdivision thereof, which federal grants are used by the commonwealth or political subdivision for the payment of salaries, and who as a result thereof is eligible for membership in the United States civil service retirement system, or who otherwise is eligible for such membership, and who also is eligible for membership in any retirement system established under this act, may have such portion of his salary, wages or other compensation as is derived from federal grants included in his regular compensation as defined by section one, but as a condition precedent to membership, he shall file an affidavit with the retirement board certifying that he is not a member of the United States civil service retirement system, eligible to make contributions thereto based upon his current salary. If the employee certifies that he is a member of the United States civil service retirement system, eligible to make contributions thereto based upon his current salary, he thereby waives all rights to membership in any retirement system established under this chapter, and no deductions shall be made from his compensation for any retirement system established under this chapter. If, when becoming a member of a retirement system established under this chapter, he is not a member of the United States civil service retirement system, eligible to make contributions thereto based upon his current salary, but later at any time before retirement becomes a member of the United States civil service retirement system, except after resignation or discharge from the service which makes him eligible to membership in a retirement system established under this chapter, he shall cease to be a member of any retirement system established under this chapter, and his accumulated deductions shall be returned to him. When he or any beneficiary of his becomes eligible to receive any benefit under this chapter, he or his beneficiary, as a condition precedent to the receipt of such benefit, shall file an affidavit stating that the member is not or was not at his death a member of or eligible to receive any benefits under the United States civil service retirement system. Eligibility for membership in a retirement system established under this chapter and the right to receive a retirement allowance or benefit thereunder shall not be affected by the receipt of a federal pension or retirement allowance by a ''veteran'' for federal service, as defined in section one, or by any potential right thereto. Any employee who on January first, nineteen hundred and fifty-two was a member of the United States civil service retirement system and also a member of a retirement system established under this chapter, and any employee who was a member of the United States civil service retirement system and thereafter ceased to be a federal employee and became eligible for membership in a retirement system established under this chapter, and any employee who was a member under this chapter and thereafter resigned or was discharged and became a federal employee, may continue his membership in both systems on the condition that he shall at his retirement, or his beneficiary shall at his death, present to the retirement board established under this chapter proof of the amount of the retirement or survivorship allowance to be received from the United States civil service retirement system, and the retirement or survivorship allowance from the system established under this chapter shall be fixed at an amount which shall not exceed the difference between the annual federal retirement or survivorship allowance and the largest annual salary received by the employee during a calendar year of the employment which made him eligible for membership in the retirement system established under this chapter.

    [There are no clauses (xii) and (xiii).]