Weighment procedure for excisable goods: pre-authorised challans and weighbridge certification required for duty assessment prior to clearance. Where a factory lacks a weighbridge, the assessee must obtain the Assistant Collector's permission naming the goods and nearest weighbridge; consignments for external weighing must move only under a separate set of serially numbered, pre-authenticated challans identifying the weighbridge and recording goods details, estimated weight, transport mode and reference to Gate Pass I. Gate Pass I is prefilled except for weighment-related fields; post-weighment endorsements and weighbridge certificates must be submitted and matched with duplicate gate passes and RT 12 monthly returns for duty assessment.