"Uuhmmm, we're not too sure that we, or some other banks we know well, will be able to easily find the most reliable data on that", a handful of banks have more or less told the banking regulator, when advised they and the sector must prepare to report in a more detailed fashion on mortgage lending metrics.In October last year, APRA outlined forthcoming, new obligations on banks "to better enable APRA's supervisory monitoring and oversight of residential mortgage lending."The Australian Prudential Regulation Authority spelled out yesterday how ADIs will be required to report more detailed data on loans originated during the quarter than required now, including information on borrowers, loan-to-income ratios, collateral type and location and a more granular breakdown by loan to valuation ratio.Banks will also be required to report information on the average variable interest rate and average loan serviceability assessment rate of loans originated during the quarter, APRA said at the time.Banks will need to report under the new format by 2018, with APRA skipping through a further round of consultation.There are tweaks for bank to work on.APRA said it "revised the definition of owner-occupied and investor loans to be based on the purpose of the loan" and "will now include data items on non-housing lending secured by residential mortgages, such as personal loans, to maintain reporting of all lending secured by residential property. Report standards on loan-to-income ratios - detail of supreme interest to APRA at the moment - will be simplified and "based on borrowers' gross income, without any discounts or haircuts."