All veterans who are basically eligible and who are unable to secure and follow a substantially gainful occupation by reason of disabilities which are likely to be permanent shall be rated as permanently and totally disabled. For the purpose of pension, the permanence of the percentage requirements of § 4.16 is a requisite. When the percentage requirements are met, and the disabilities involved are of a permanent nature, a rating of permanent and total disability will be assigned if the veteran is found to be unable to secure and follow substantially gainful employment by reason of such disability. Prior employment or unemployment status is immaterial if in the judgment of the rating board the veteran's disabilities render him or her unemployable. In making such determinations, the following guidelines will be used:
38 C.F.R. §4.17
Authority: 38 U.S.C. 1155 ; 38 U.S.C. 3102