:- use_module(library(semweb/rdf11)).
An RDF literal term is of the form String@LanguageTag or
Value^^Datatype.
Success of this goal does not imply that the literal is well-formed or that it is present in the database (see rdf_literal/1 for that).
:- use_module(library(semweb/rdf_db)).
[semidet]rdf_is_literal(@Term)