The purpose of this part is to prescribe rules governing the calculation and payment of benefits payable in terminated single-employer plans under section 4022 of ERISA. Subpart A, which applies to each plan providing benefits guaranteed under title IV of ERISA, contains definitions applicable to all subparts, and describes benefits that are guaranteed by the PBGC subject to the limitations set forth in subpart B. Subpart C is reserved for rules relating to the calculation and payment of unfunded nonguaranteed benefits under section 4022(c) of ERISA. Subpart D prescribes procedures that minimize the overpayment of benefits by plan administrators after initiating distress terminations of single-employer plans that are not expected to be sufficient for guaranteed benefits. Subpart E sets forth the method of recoupment of benefit payments in excess of the amounts permitted under sections 4022, 4022B, and 4044 of ERISA from participants and beneficiaries in PBGC-trusteed plans, and provides for reimbursement of benefit underpayments. (The provisions of this part have not been amended to take account of changes made in section 4022 of ERISA by sections 766 and 777 of the Retirement Protection Act of 1994.)