Maryland State Personnel and Pensions Section 25-303
§ 25-303.
  Eligibility service for a member consists of service credit:
    (1)   for employment as a member;
    (2)   regained under § 25-304 of this subtitle by a member who redeposits accumulated contributions previously withdrawn;
    (3)   transferred from a retirement or pension system under Title 37 of this article or Title 31, Subtitle 1 of this article;
    (4)   for military service as provided in Title 38 of this article;
    (5)   purchased under this subtitle; or
    (6)   transferred from the Employees' Pension System under § 25-306.1 of this subtitle.