(4)The Commissioner shall not revise any order under this section in the following cases- (a) where an appeal against the order lies to the Appellate Assistant Commissioner or to the Appellate Tribunal but has not been made and the time within which such appeal may be made has not expired, or the assessee has not waived his right of appeal; or(b)where the order is pending on an appeal before the Appellate Assistant Commissioner; or(c)where the order has been made the subject of an appeal to the Appellate Tribunal.
