FOREIGN TRADE ZONES 21 
warehouses and smelting and refining warehouses are special classes, 
for which separate rules and regulations have been prescribed by 
the Customs Service. 
Drawback —Merchandise upon which duties have been paid and 
which have remained continuously in bonded warehouse or otherwise 
in the custody and control of customs officials may be entered or 
withdrawn at any time within three years from date of importation 
for exportation or for transportation and exportation. Upon such 
entry or withdrawal 99 per cent of the duty paid thereon may be 
refunded. Upon exportation of articles manufactured or produced 
in the United States with the use of imported merchandise, the duties 
paid on the merchandise so used less 1 per cent of such duty may be 
refunded as drawback, except that such duty shall not be so refunded 
apon the exportation of flour or by-products produced from imported 
wheat unless an amount of wheat grown in the United States equal 
to not less than 30 per cent of the amount of such import wheat has 
been mixed with such import wheat. This provision also applies to 
vessels constructed and equipped in the United States with the use 
of imported materials for foreign account and ownership, or for the 
government of any foreign country. 
As exportation contemplates shipment to a foreign country, draw- 
back can not be allowed on shipments to United States possessions, 
unless the same is authorized by specific provision of law or by 
necessary implication. No drawback of additional duty imposed for 
undervaluation, nor of discriminating duty, nor of additional duty 
paid on any wool used in violation of the bond provided for in para- 
graph 1101 of the tariff act of 1922, nor on merchandise remaining 
nelaimed in general order for more than one year, will be allowed. 
The entry or withdrawal of merchandise in customs custody for 
exportation with benefit of drawback must be made within three 
years from the date of importation. No drawback will be paid unless 
the merchandise is exported in the original packages in which imported, 
without diminution or change in quantity, quality, or value, unavoidable 
wastage or damage excepted, or in the packages to which transferred 
when repacked under special authority. No drawback will be allowed 
on any merchandise if it has been released from the custody or con- 
trol of the government prior to being laden for exportation, as such 
custody must be continuous and uninterrupted from the time of 
importation until the time of exportation. Drawback will not be 
allowed on merchandise loaded at night or on Sundays or legal 
holidays without customs inspection and supervision. 
It is essential in the administration of the drawback law that 
exporters in all cases provide the requisite opportunity and the nec- 
essary facilities for official inspection, sampling and ascertainment of 
quantities. Collectors, in their discretion, indicate on the notices of