Section 10k(9)(a) in The Standards of Weights and Measures (General) Rules, 1987
(a)For instrument of class II, III or IV liable to be tilted, the influence of tilting shall be determined under the effect of a lengthwise or transverse tilting equal to 2/1000 or corresponding to the limiting value of tilting marked on, or indicated by a level indicator, whichever is the greater tilt.