§ 652. Definitions. a. The term "normal retirement age" shall mean age fifty-five for a member of Tier one, and age sixty-two for a member of Tier two, three or four.

b. The term "covered employment" shall mean paid service as a bridge and tunnel officer, sergeant, lieutenant, assistant bridge and tunnel maintainer, bridge and tunnel maintainer, senior bridge and tunnel maintainer or laborer with the Triborough bridge and tunnel authority by a member described in section six hundred fifty of this article.

c. The term "Tier one member" shall mean a member whose benefits are prescribed by chapter one of title thirteen of the administrative code of the city of New York and who is not subject to the provisions of article eleven, fourteen or fifteen of this chapter.

d. The term "Tier two member" shall mean a member whose benefits are prescribed by chapter one of title thirteen of the administrative code of the city of New York and who is subject to the provisions of article eleven of this chapter.

e. The term "Tier three member" shall mean a member who is subject to the provisions of article fourteen of this chapter.

f. The term "Tier four member" shall mean a member who is subject to the provisions of article fifteen of this chapter.