Revision power of Commissioner allows review of subordinate assessments, subject to hearing rights, appeal bar and limitation rules. Commissioner may call for records and make enquiries into proceedings of a subordinate Assessing Officer and pass such orders on his own motion or on assessee's application, subject to the Act. No adverse order without an opportunity to be heard; no revision while an appeal against the notice of demand is pending before Commissioner (Appeals); revision barred after two years from end of the financial year in which the order sought to be reviewed was passed. Time limits for disposal of applications are subject to exclusions for re hearing and court stays, and revisions may be made to implement appellate or judicial directions.