Pass Book-based customs exemption permits duty-free import of inputs subject to credit verification, input norms, valuation and non-transferability. Imports against a Pass Book issued under paragraph 54 of the Export and Import Policy 1992-97 are exempt from basic customs duty and, if claimed, the additional duty, provided the importer holds an authorised Pass Book with credited basic duty entries verified by customs. Credits are limited to inputs specified in standard input-output norms, require proof of actual use and prime quality, are subject to valuation rules using specified sequential methods, and cannot exceed seventy-five percent of FOB value unless authorised. The Pass Book must be produced for debiting, is non-transferable, and credits lapse under the prescribed validity periods.