Mark-to-market loss deductions are restricted to losses computed strictly under prescribed accounting standards. No deduction is generally allowable for mark-to-market losses or other anticipated losses. An exception applies only where the loss is calculated strictly in accordance with the Income Computation and Disclosure Standards, specifically ICDS VI, as notified under the relevant provision. Under the earlier law, no deduction or allowance is permitted for marked-to-market loss or other expected loss except to the extent otherwise allowable under the specified deduction clause.