S. 263 : Commissioner-Revision of orders prejudicial to revenue-Business expenditure-Disallowance-Payments liable to deduction of tax at source-Amount offered to tax by payee and tax thereon paid-AO taking one plausible view-Order not erroneous or prejudicial to Revenue-Principal Commissioner cannot invoke revisional power-Not in default. [S. 40(a)(ia), 201(1), 260A]