Although additional abbreviated forms for writing RDF/XML are available, the facilities illustrated so far provide a simple but general way to express graphs in RDF/XML. Using these facilities, an RDF graph is written in RDF/XML as follows: - All blank nodes are assigned blank node identifiers. - Each node is listed in turn as the subject of an un-nested rdf:Description element, using an rdf:about attribute if the node has a URIref, or an rdf:nodeID attribute if the node is blank. For each triple with this node as subject, an appropriate property element is created, with either literal content (possibly empty), an rdf:resource attribute specifying the object of the triple (if the object node has a URIref), or an rdf:nodeID attribute specifying the object of the triple (if the object node is blank).