RDF/XML, is an XML serialization of RDF graphs and one of the technologies underlying the Semantic Web. CL-RDFXML builds upon CXML (for XML processing) and Puri (for URIs).
ASDF-install package (obsolete) http://www.cs.rpi.edu/~tayloj/CL-RDFXML/cl-rdfxml_0.9.tar.gz