(1)Where the rent of a holding has been commuted under section 40, it shall not, except on the grounds specified in clauses (ii) and (iii) of section 30 or on the ground of a subsequent alteration of the area of the holding, be enhanced for twenty years, nor shall it be reduced for twenty years save on the ground of alteration in the area of the holding or on the ground specified in clauses (a) and (b) of sub-section (1) of section 38.
