Deductions. The deductions described in this subparagraph are allowances (and amounts treated as allowances) for depreciation or amortization (other than amortization under section 168, 169 (as enacted by section 704(a), Tax Reform Act of 1969 (83 Stat. 667)), or 185). Thus, for example, such deductions include a reasonable allowance for exhaustion, wear, and tear (including a reasonable allowance for obsolesence) under section 167, the periodic deductions referred to in 1.16211 in respect of a specified sum paid for the acquisition of a leasehold and in respect of the cost to a lessee of improvements on property of which he is the lessee. However, such deductions do not include deductions for the periodic payment of rent.