Invoice authentication under Rule 57G: officer availability extended to weekends and holidays to permit timely dispatch. Certain excise invoices issued by registered second-stage dealers, registered importers (including from registered depots or consignment agent premises), and first- or second-stage dealers of imported goods require authentication by the proper officer. In response to industry representations about delays in obtaining such authentication, divisional offices will maintain staff on Saturdays, Sundays and holidays from 11 A.M. to 1 P.M. to authenticate invoices and facilitate timely dispatch.