19 CFR § 19.13a - Recordkeeping requirements.
The proprietor of a manufacturing warehouse shall comply with the recordkeeping requirements of §§ 19.4(b) and 19.12. In addition, the proprietor shall:
(a) Record all transfers from any storage area to a manufacturing area, and record all transfers from a manufacturing area to a finished product storage area, in the proprietor's inventory control and accounting records;
(b) Take an annual physical inventory of the merchandise as provided in § 19.12(d)(5) in conjunction with the annual submission required by § 19.12(g); and
(c) Record all manufacturing operations performed within the warehouse with sufficient detail to determine whether there has been compliance with the manufacturing formula filed with Customs and to permit Customs to audit use and disposition of the merchandise.