The RDF vocabulary (rdfV) is a set of IRI references in the RDF namespace, http://www.w3.org/1999/02/22-rdf-syntax-ns#. The rdf:type predicate expresses class membership, rdf:Property is the class of properties, rdf:XMLLiteral is the datatype of XML literals, rdf:List, rdf:first, rdf:rest, and rdf:nil can be used to write lists (RDF collections). Ordered, unordered, and alternate containers of values can be described using rdf:Seq, rdf:Bag, rdf:Alt, rdf:_1, rdf:_2. Reification can be expressed with rdf:Statement, rdf:subject, rdf:predicate, and rdf:object. Structured values are described using rdf:value.