In this Act, unless the context otherwise requires,-

(4). "adjudicating authority" means any authority, appointed or authorised to pass any order or decision under this Act, but does not include the Commissioner, Revisional Authority, the Authority for Advance Ruling, the Appellate Authority for Advance Ruling,the Appellate Authority, the Appellate Tribunal and the Authority referred to in sub-section (2) of section 171;