22 C.F.R. § 20.1
As used in this part, unless otherwise specified, the following have the meaning indicated:
COLA means cost-of-living adjustment in annuity.
Creditable service or service means employment or other periods that are counted under sections 816, 817, or 854 in determining retirement benefits.
Disability annuitant means a participant in FSRDS or FSPS entitled to a disability annuity under section 808 of the Act or subchapter V, chapter 84, title 5 U.S.C., and a disability annuity means a Foreign Service annuity computed under those sections.
FSRDS means the Foreign Service Retirement and Disability System established by subchapter I, chapter 8, of the Act.
FSPS means the Foreign Service Pension System established by subchapter II, chapter 8, of the Act.
Former spouse means a former wife or husband of a participant or former participant who was married to such participant for not less than 10 years during service of the participant which is creditable under chapter 8 of the Act with at least 5 years occurring while the employee was a member of the Foreign Service and who retired from the Foreign Service Retirement System.
Full annuity equals the annuity the former participant would be eligible to receive except for deductions made to provide survivor benefits or because of payment of a portion of the annuity to others.
Participant means a person who contributes to the Fund identified in § 20.2 . Such person may participate in either FSRDS or FSPS.
Principal means a participant or former participant whose service forms the basis for a benefit for a former spouse under this part.
Pro rata share, in the case of a former spouse of a participant or former participant, means the percentage obtained by dividing the number of months during which the former spouse was married to the participant during the creditable service of the participant by the total number of months of such creditable service. In the total period, 30 days constitutes a month and any period of less than 30 days is not counted. When making this calculation for a former spouse married to a participant during a period the participant earned extra service credit under section 817 of the Act, the number of months of such extra service credit earned during that period of the marriage shall be added to the total number of months of the marriage.
22 C.F.R. § 20.1