code: protected function toXMLFragment()
      {
          $xml = "";
          foreach ($this->fields as $fieldName => $field) {
              $fieldValue = $field['FieldValue'];
              if (!is_null($fieldValue)) {
                  $fieldType = $field['FieldType'];
                  if (is_array($fieldType)) {
                      if ($this->isComplexType($fieldType[0])) {
                          foreach ($fieldValue as $item) {
                              $xml .= "<$fieldName>";
                              $xml .= $item->toXMLFragment();
                              $xml .= "</$fieldName>";
                          }
                      } else {
                          foreach ($fieldValue as $item) {
                              $xml .= "<$fieldName>";
                              $xml .= $this->escapeXML($item);
                              $xml .= "</$fieldName>";
                          }
                      }
                  } else {
                      if ($this->isComplexType($fieldType)) {
                          $xml .= "<$fieldName>";
                          $xml .= $fieldValue->toXMLFragment();
                          $xml .= "</$fieldName>";
                      } else {
                          $xml .= "<$fieldName>";
                          $xml .= $this->escapeXML($fieldValue);
                          $xml .= "</$fieldName>";
                      }
                  }
              }
          }
          return $xml;
      }
docs: XML fragment representation of this object
  Note, name of the root determined by caller
  This fragment returns inner fields representation only
  @return string XML fragment for this object