38 CFR §7.2

1. (a)A statement over the signature of the Commanding Officer or a commissioned officer of equal or higher rank than the insured, on the insured's application, may be accepted as a certification that the insured is a person in the military service.
2. (b)If the insured is unavailable because of service, the application may be certified by the person who has custody of the insured's service record.
3. (c)If an application is submitted by a person designated by the insured or by the insured's beneficiary, the Department of Veterans Affairs will obtain from the service department evidence that the insured is a person in the military service.