What serves as the unique key for the Prior Notice submissions?

What serves as the unique key for the Prior Notice submissions?

For FDA, this, along with a filer or issuer code of the bill of lading and Reference Identifier number, serves as the unique key for the Prior Notice submission.

ENT Entry number

BOL Bill of Lading Number (Ocean, Rail or Truck)

AWB Air waybill

FTZ FTZ admission number

INB In-bond number