Section 6(1)(v) in The Tinsukia and Dibrugarh Electric Supply Undertakings (Acquisition) Act, 1973
(v)the book value of all plants and equipments existing on the vesting date, if taken over by the Government, but no longer in use owing to wear and tear or to obsolescence, to the extent such value has not been written off in the books of the licensee less depreciation calculated in accordance with Schedule I;