The revision of a decision on which an action was predicated will be subject to the following sections:
(a) Clear and unmistakable error, § 3.105(a) of this chapter;(b) Difference of opinion, § 3.105(b) of this chapter;(c) Character of discharge, § 3.105(c) of this chapter;(d) Severance of service connection, § 3.105(d) of this chapter;(e) Veteran no longer totally and permanently disabled, § 21.4135(o) .