38 CFR § 3.15 - Computation of service.
For nonservice-connected or service-connected benefits, active service is countable exclusive of time spent on an industrial, agricultural, or indefinite furlough, time lost on absence without leave (without pay), under arrest (without acquittal), in desertion, while undergoing sentence of court-martial or a period following release from active duty under the circumstances outlined in § 3.41. In claims based on Spanish-American War service, leave authorized under General Order No. 130, War Department, is included.
Duty periods. See § 3.6(b)(6).