The Supplemental Register is a secondary list of registered marks maintained by the USPTO. Marks on the Supplemental Register do not qualify for registration on the Principal Register, and as such, these marks do not receive the many benefits of registration available on the Principal Register. However, registration on the Supplemental Register allows the mark owner to use the ® symbol next to their mark, and also provides notice to potential users of the mark that the mark is already being used.
Typically, Supplemental Register marks are those that are registered in foreign countries but not yet used in the United States, as well as those that are not descriptive. Once a mark becomes distinctive through extensive use, or has been on the Supplemental Register for five years, the mark owner may petition to have it moved to the Principal Register.