31 C.F.R. § 29.402
In this subpart-
Beneficiary means an individual designated by a participant, or by the terms of the Judges Plan, Police and Firefighters Plan, or Teachers Plan, who is or may become entitled to a benefit under those plans.
Claimant means any person seeking a benefit for themselves or another under the Judges Plan, Police and Firefighters Plan, or Teachers Plan.
Department means the Secretary of the Treasury or a designee authorized to exercise the Secretary's authority with respect to Federal Benefit Payments under the Act.
Participant means an individual who is or may become eligible to receive a benefit under the Police and Firefighters Plan or the Teachers Plan based on credit for service accrued as of June 30, 1997, or under the Judges Plan, or whose beneficiaries may be eligible to receive any such benefit.
31 C.F.R. §29.402