Section 21(v) in The U.P. Cinematograph Rules, 1951
(v)The openings in front of the projection room for each projection machine shall not be more than three in number of which the middle one shall not exceed 8 inches square and the other shall not be more than 5 inches square. Each such aperture shall be provided with a fire proof place glass screen not less than 5/ 16 inch thick fixed in position with some light joints.
