Since the value that a given typed literal denotes is defined by the typed literal's datatype, and, with the exception of rdf:XMLLiteral, RDF does not define any datatypes, the actual interpretation of a typed literal appearing in an RDF graph (e.g., determining the value it denotes) must be performed by software that is written to correctly process not only RDF, but the typed literal's datatype as well. Effectively, this software must be written to process an extended language that includes not only RDF, but also the datatype, as part of its built-in vocabulary.