code: public void processingInstruction(String target, String data)
              throws SAXException {
          write(nl + "     <?" + target + " " + data + "?>");
      }
docs: Overrides <code>processingInstruction(String <i>target</i>,
  String <i>data</i>)</code> in
  <code>org.xml.sax.helpers.DefaultHandler</code>,
  which in turn implements <code>org.xml.sax.ContentHandler</code>.
  Called whenever a processing instruction (PI) is encountered.