(iii)where a Government servant is formally appointed to hold charge of another post or posts which is or are not in the same office, or which, though in the same office, is or are not in the same cadre/ line of promotion, he shall be allowed the pay of the higher post, or the highest post if he holds charge of more than two posts, in addition to ten percent of the presumptive pay of the additional post or posts, if the additional charge is held for a period exceeding thirty days but not exceeding ninety days :
