Use the country codes below to identify the origination of the National Stock Number (NSN) for a part. The NSN is a 13-digit number assigned to a part under the Federal Cataloging System. The first four digits of the NSN are the Federal Supply Class (FSC) of the part. The second two digits are the County of Origin Code and signify the country that assigned the NSN, and the last seven digits are the unique code number for the part. Each item cataloged in the Federal Supply System is assigned a unique number. Together, the Country of Origin Code and the unique item number make up the National Item Identification Number, or NIIN.