Furthermore, a term that is not initially generic may become so, if consumers come to believe that a mark is the generic name for a type of product. Marks that have become generic include aspirin, cellophane and escalator. Virtually anything capable of indicating source may serve as a trademark. Letters and numbers may be used as marks. For example, ABC, CBS and NBC are readily recognizable as the service marks of major radio and television broadcasting networks.
Slogans can function as marks.
A color or combination of colors may function as an indicator of source and be registered as a trademark. Musical notes and other sounds have been federally registered. A federal registration has even been granted for a particular fragrance, reminiscent of plumeria, used to identify sewing thread. However, if other physical arrangements can do the same functions without sacrificing a functional advantage, the design may be considered nonfunctional. The law protects trademarks based on bona fide commercial use in commerce subject to Congressional regulation.