19 C.F.R. § 4.38
(a) No imported merchandise shall be released from Customs custody until a permit to release such merchandise has been granted. Such permit shall be issued by the port director only after the merchandise has been entered and, except as provided for in § 141.102(d) or part 142 of this chapter, the duties thereon, if any, have been estimated and paid. Generally, the permit shall consist of a document authorizing delivery of a particular shipment or an electronic equivalent. Alternatively, the permit may consist of a report which lists those shipments which have been authorized for release. This alternative cargo release notification may be used when the manifest is not filed by the carrier through the Automated Manifest System, the entry has been filed through the Automated Broker Interface, and Customs has approved the cargo for release without submission of paper documents after reviewing the entry data submitted electronically through ABI and its selectivity criteria (see § 143.34). The report shall be posted in a conspicuous area to which the public has access in the customhouse at the port of entry where the cargo was imported.
(1) Where the cargo arrives by vessel, the report shall consist of the following data elements:
(2) Where the cargo arrives by air, the report shall consist of the following data elements:
(3) In the case of merchandise traveling via in-bond movement, the report will contain the following data elements:
(iv) Entry number (including filer code).
When merchandise is released without proper permit before entry has been made, the port director shall issue a written demand for redelivery. The carrier or facility operator shall redeliver the merchandise to Customs within 30 days after the demand is made. The port director may authorize unentered merchandise brought in by one carrier for the account of another carrier to be transferred within the port to the latter carrier's facility. Upon receipt of the merchandise the latter carrier assumes liability for the merchandise to the same extent as though the merchandise had arrived on its own vessel.
(c) If the port director determines that, in a port or portion of a port, the volume of cargo handled, the incidence of theft or pilferage, or any other factor related to the protection of merchandise in Customs custody requires such measures, he shall require as a condition to the granting of a permit to release imported merchandise that the importer or his agent present to the carrier or his agent a fully executed pickup order in substantially the following format, in triplicate, to obtain delivery of any imported merchandise:

The pickup order shall contain a duly authenticated customhouse broker's signature, unless it is presented by a person properly identified as an employee or agent of the ultimate consignee. When delivered quantities are verified by a Customs officer, he shall certify all copies of the pickup order, returning one to the importer or his agent and two to the carrier making delivery.
[28 FR 14596, Dec. 31, 1963, as amended by T.D. 71-39, 36 FR 1892, Feb. 3, 1971; T.D. 77-255, 42 FR 56321, Oct. 25, 1977; T.D. 91-46, 56 FR 22330, May 15, 1991; 56 FR 27559, June 14, 1991]