On May 3, 2017 U.S. Customs and Border Protection (CBP) released Cargo Systems Messaging Service (CSMS) #17-000255 in partnership with the U.S. Foods and Drug Administration (FDA) regarding certain FSVP requirements.
According to the CSMS, in an effort to assist the trade while the FSVP is being on boarded, the FDA will allow for the temporarily filing of “UNK” (unknown) as a Unique Facility Identifier. UNK may only be used if the importer does not yet have a nine-digit, site specific DUNS number. A DUNS number will be unique for each location under an importer.
Read more at expeditors.com