Section 87

The declarations referred to in sections 85 and 86 shall give a full and true account of the particulars for which provision is made:

Provided that if, in the case of imported goods, any of the particulars required are unknown to the importer thereof, delivery of such goods may be given on a written undertaking of the importer or his agent to furnish the necessary information to the proper officer of excise within 10 days of such undertaking or such further period as the proper officer of excise may allow, and if the importer or his agent fails to furnish the information as required by the undertaking, he shall be deemed to have failed to make the required declaration.