5 C.F.R. § 630.204
Fractional pay periods
When an employee's service is interrupted by a non-leave-earning period, he earns leave on a pro rata basis for each fractional pay period that occurs within the continuity of his employment.
When an employee's service is interrupted by a non-leave-earning period, he earns leave on a pro rata basis for each fractional pay period that occurs within the continuity of his employment.