10. The Commissioner may, with prior approval of the Board, by general or a special order in writing, direct that in respect of all or any proceedings relating to specified cases or classes of cases or specified persons of classes of persons within his jurisdiction, the powers and functions of the Deputy Commissioner of Taxes, ²[Inspecting Joint Commissioner, the Inspecting Additional Commissioner] and the Commissioner under this Ordinance shall be exercised by ³[Inspecting Joint Commissioner, the Inspecting Additional Commissioner], the Commissioner and the Board, respectively and for the purpose of any proceedings in respect of such cases or persons reference in this Ordinance or the rules made thereunder to the Deputy Commissioner of Taxes, ⁴[Inspecting Joint Commissioner, the Inspecting Additional Commissioner] or the Commissioner shall be deemed to be references to ⁵[Inspecting Joint Commissioner, the Inspecting Additional Commissioner], the Commissioner and the Board, respectively.