S. 50 :Capital gains-Depreciable assets-Block of assets-Rate of tax-Deeming fiction is to be confined only to section 50 and it could not convert short term capital asset into long term capital asset and vice versa for other purpose of Act-Rate of tax would be in terms of section 112 at rate of 20 percent and not 30 percent.[S. 2(29AA) 2(29B), 2(42A), 45, 48,49, 112(1)]