38 CFR §21.414
The revision of a decision on which an action is based is subject to the following regulations:
- (a)Clear and unmistakable error, § 3.105(a);
- (b)Difference of opinion, § 3.105(b);
- (c)Character of discharge, § 3.105(c);
- (d)Severance of service-connection, § 3.105(d);
- (e)Reduction to less than compensable evaluation, § 3.105(e); (See §§ 21.48, 21.322, and 21.324)
- (f)Review of decisions, § 21.416.