code: private void processNavitation(final Element topicref) {
          // create new map's root element
          final Element root = (Element) topicref.getOwnerDocument().getDocumentElement().cloneNode(false);
          // create navref element
          final Element navref = topicref.getOwnerDocument().createElement(MAP_NAVREF.localName);
          final String newMapFile = chunkFilenameGenerator.generateFilename("MAPCHUNK", FILE_EXTENSION_DITAMAP);
          navref.setAttribute(ATTRIBUTE_NAME_MAPREF, newMapFile);
          navref.setAttribute(ATTRIBUTE_NAME_CLASS, MAP_NAVREF.toString());
          // replace topicref with navref
          topicref.getParentNode().replaceChild(navref, topicref);
          root.appendChild(topicref);
          // generate new file
          final URI navmap = currentFile.resolve(newMapFile);
          changeTable.put(stripFragment(navmap), stripFragment(navmap));
          outputMapFile(navmap, buildOutputDocument(root));
      }
docs: Create new map and refer to it with navref.