A Facilities Information and Resources Management System (FIRMS) Code is a four-digit alpha-numeric identifier assigned by U.S. Customs and Border Protection to:
- Container Freight Stations,
- Warehouse Deconsolidators,
- Foreign Trade Zones,
- Bonded Warehouses,
- or any other US Customs Service bonded facility.
The FIRMS Code represents the location of certain goods. The FIRMS location must be bonded and on file in Automated Manifest System (AMS). The FIRMS Code is assigned to a location when the bond for that location has been filed with Customs and Border Protection.
CBP does provide Form Code List, you can check the below link.
Friendly warning: Call the location to make sure your input the right code as Firms code is always being updated by the owner of the code.