Tax depreciation v. Actual depreciation.  If property is depreciating by 10%/year, but the debtor depreciates it at 20%/year for tax purposes, the creditor may try to argue that protection for 20% depreciation needs to be provided.  Debtor would argue that there is an artificiality to the tax process, so 10% is fine.  This latter arg makes more sense since you need to make sure creditor gets full value and nothing more—if they get prop at end of year, plus 20% depreciation from debtor and then sell prop that has only depreciated 10%, they have been overpaid.