Section 100(1)(ii) in The Central Motor Vehicles Rules, 1989
(ii)any windscreen or window at the front of the vehicle, the inner surface of which is at an angle [more than thirty degrees] [Substituted by GSR 214(E), dated 18.3.1999, for 'extending to thirty degrees' (w.e.f. 18.3.1999).] to the longitudinal axis of the vehicle shall be deemed to face to the front.