When a generic name is repeated in specific name of a species, it is called tautonym. A tautonym is a scientific name of a species in which both parts of the name (the genera and species) have the same spelling. For example, Bison bison for American Bison. It is a binary combination of the generic name. The use of tautonyms is not allowed by International Code. However, it is valid names according to ICZN (International Code of Zoological Nomenclature). Hence, tautonyms are not accepted by botanical nomenclature although they are allowed in zoological nomenclature.