38 CFR 3.17: Disability and survivors pension; Mexican border period and later war periods.

In computing the 90 days' service required for pension entitlement (see § 3.3), there will be included active service which began before and extended into the Mexican border period or ended during World War I, or began or ended during World War II, the Korean conflict, the Vietnam era or the Persian Gulf War, if such service was continuous. Service during different war periods may be combined with service during any other war period to meet the 90 days' service requirement.