if (exp.dt instanceof XSDatatypeImpl) {
XSDatatypeImpl base = (XSDatatypeImpl)exp.dt;
final Vector ns = new Vector();
String lex = base.convertToLexicalValue(exp.value, new SerializationContext() {
public String getNamespacePrefix(String namespaceURI) {
int cnt = ns.size() / 2;
ns.add("xmlns:ns" + cnt);
ns.add(namespaceURI);
return "ns" + cnt;