case Node.ENTITY_NODE :
case Node.NOTATION_NODE :
case Node.DOCUMENT_FRAGMENT_NODE :
case Node.ATTRIBUTE_NODE :
throw new CanonicalizationException("empty");
case Node.DOCUMENT_NODE :
for (Node currentChild = currentNode.getFirstChild();
currentChild != null;
currentChild = currentChild.getNextSibling()) {
canonicalizeXPathNodeSet(currentChild,ns);