@Override
 public void beginHeader(int level, WikiParameters params) {
   beginElement();
   super.beginHeader(level, params);
   if (toc != null) {
     String id = toc.addHeading(null, level); // we don't know the title yet
     print("<a name=\"heading_" + id + "\">");
     mark = writer.getBuffer().length();
   }
 }