53. (1) Every application for port-clearance shall be made by the master of a vessel at least twenty-four hours before the intended departure of the vessel: Provided that the ¹[Commissioner of Customs] or an officer authorised by him in this behalf may for special reasons to be recorded allow a shorter period for the delivery of the said application. ²[: ³[Provided further that when the master is a registered user, he may make the application under this sub-section by transmitting it to the Customs computer system, and an application so transmitted shall be deemed to have been duly signed by him.]]. (2) The master shall, at the time of applying for port-clearance,-(a) deliver to the appropriate officer an export manifest in duplicate in such form as may from time to time be prescribed by the Board signed by such master specifying all goods to be exported in the vessel and showing separately all goods and stores entered in the import manifest, and not landed or consumed on board or transhipped;(b) deliver to the appropriate officer such bills of export or other documents as such officer acting under the general instructions of the Commissioner of Customs requires; and(c) answer such questions respecting the departure and destination of the vessel as are put to him by the appropriate officer ⁴[: Provided that if the master is a registered user, he may transmit to the Customs computer system the export manifest and other documents specified at clauses (b) and (c) and the documents so transmitted shall be deemed to have been signed by him for the purposes of this section.] (3) The provisions of section 45, relating to the amendment of import manifests shall, mutatis mutandis, apply also to export manifest delivered under this section or under section 54.