Rehabilitation allowance permits a deduction of qualifying depreciation when an industrial business is re-established after destruction. Rehabilitation allowance allows an assessee who discontinues an industrial business due to prescribed causes (natural convulsion, riot, accidental fire or explosion, or enemy action) and thereafter re-establishes or reconstructs the business within three years to claim, in the year of re-establishment, a deduction equal to sixty percent of the deduction otherwise allowable under clause (iii) of section 32(1) for the damaged or destroyed building, machinery, plant or furniture. 'Industrial undertaking' is defined to include generation or distribution of power, ship construction, manufacture or processing of goods, and mining.