DocumentBuilder db = dbf.newDocumentBuilder();
            Document doc = db.newDocument();

            Element root = doc.createElement(ROOT);
            doc.appendChild(root);

            stack.serializeTo(root);
            track.createReverseStack().serializeTo(root);

            OutputFormat of = new OutputFormat(doc, "utf-8", true);
            XMLSerializer serializer = new XMLSerializer(os, of);
            serializer.processingInstruction("xml-stylesheet", "type=\"text/xsl\" href=\"demo.xsl\"");
            serializer.asDOMSerializer().serialize(doc);