Section 8(1) in The Indian Supply Service (Group `A') Rules, 2017
(1)The relative seniority of the members of the Service shall be in accordance with the relative seniority in their respective grades as already determined before the commencement of these rules:Provided that if the seniority of any such member had not been determined before the commencement of these rules, it shall be determined by the cadre controlling authority in accordance with the general orders or instructions on seniority issued by the Central Government from time to time.
