Section 128(10)(ii) in The Central Motor Vehicles Rules, 1989
(ii)Seating layout shall be [two and two or one and two or one and one] [Substituted by GSR 933(E), dated 28.10.1989, for 'two and two'(w.e.f. 28.10.1989). ] on either side, all seats facing forward, with a clear gangway of at least 355 millimetres width at the centre. Each passenger seat shall have a minimum area of 447 millimetres × 457 millimetres and an arm rest on both sides and seat back of full height.