5 C.F.R. § 630.603
For the purpose of this subpart, service abroad:
(c) Includes (1) absence in a nonpay status up to a maximum of 2 workweeks within each 12 months of service abroad, (2) authorized leave with pay, (3) time spent in the Armed Forces of the United States which interrupts service abroad (but only for eligibility, not leave-earning, purposes), and (4) a period of detail.
In computing service abroad, full credit is given for the day of arrival and the day of departure.
[33 FR 12475, Sept. 4, 1968, as amended at 35 FR 14763, Sept. 23, 1970]