(b)empower the Director-General or Chief Commissioner or Commissioner to issue orders in writing that the powers and functions conferred on, or, as the case may be, assigned to, the Assessing Officer by or under this Act in respect of any specified area or persons or classes of persons or incomes or classes of income or cases or classes of cases, shall be exercised or performed by ] [an Additional Commissioner] [ Inserted by Act 22 of 2007, Section 42 (w.r.e.f. 1.6. 1994).] [or an Additional Director or] [ Inserted by Act 22 of 2007, Section 42 (w.r.e.f. 1.10.1996).][a] [Substituted by Act 4 of 1988, Section 32, for Section 120 (w.e.f. 1.4.1988).][Joint Commissioner] [ Substituted by Act 21 of 1998, Section 3, for " Deputy Commissioner" and " Deputy Director" , respectively (w.e.f. 1.10.1998).][or] [Substituted by Act 4 of 1988, Section 32, for Section 120 (w.e.f. 1.4.1988).][a [Joint Director] [Substituted by Act 33 of 1996, Section 41, for certain words (w.e.f. 1.10.1996).][, and, where any order is made under this clause, references in any other provision of this Act, or in any rule made thereunder to the Assessing Officer shall be deemed to be references to such ] [Substituted by Act 4 of 1988, Section 32, for Section 120 (w.e.f. 1.4.1988).][Additional Commissioner or] [ Inserted by Act 22 of 2007, Section 42 (w.r.e.f. 1.6. 1994).][an Additional Director or] [ Inserted by Act 22 of 2007, Section 42 (w.r.e.f. 1.10.1996).][joint Commissioner or ] [Substituted by Act 4 of 1988, Section 32, for Section 120 (w.e.f. 1.4.1988).] [Joint Director] [Substituted by Act 33 of 1996, Section 41, for certain words (w.e.f. 1.10.1996).][by whom the powers and functions are to be exercised or performed under such order, and any provision of this Act requiring approval or sanction of the ] [Substituted by Act 4 of 1988, Section 32, for Section 120 (w.e.f. 1.4.1988).] [Joint Commissioner] [ Substituted by Act 21 of 1998, Section 3, for " Deputy Commissioner" and " Deputy Director" , respectively (w.e.f. 1.10.1998).][shall not apply. [Substituted by Act 4 of 1988, Section 32, for Section 120 (w.e.f. 1.4.1988).]