code: private function writeFileVersion(XMLWriter $objWriter)
      {
          $objWriter->startElement('fileVersion');
          $objWriter->writeAttribute('appName', 'xl');
          $objWriter->writeAttribute('lastEdited', '4');
          $objWriter->writeAttribute('lowestEdited', '4');
          $objWriter->writeAttribute('rupBuild', '4505');
          $objWriter->endElement();
      }
docs: Write file version.
  
  @param XMLWriter $objWriter XML Writer