The FCC is a two-part code that defines an update to a product in the FCC database. This code is defined in the Code of Federal Regulations, Title 47, volume 2.
Part 1 is the Grantee Code. This consists of 3 to 5 characters (either letters or numbers) that is given to a grantee or an applicant when interacting with the FCC.
If a code begins with a letter then it will consists of three letters. All letters are capitalized.
If a code begins with a number then it will be five characters, either letters or numbers may appear. All letters are capitalized. No ones or zeros are used.
These codes are permanent and will persist across a company during its dealings with the FCC.
Part 2 of an FCC ID is the product code.
Product codes are determines by the grantee, not the FCC, and have to be unique for each product that is to be approved by the Telecommunication Certification Body (TCB).
A product code can be up to 14 characters long, containing capital letters, numbers, and hyphens. Consecutive hyphens are not allowed nor are special characters (like question marks).