private function _writeRichTextString($row, $col, $str, $xfIndex, $arrcRun){
		$record	= 0x00FD;				   // Record identifier
		$length	= 0x000A;				   // Bytes to follow
		$str = PHPExcel_Shared_String::UTF8toBIFF8UnicodeShort($str, $arrcRun);

		/* check if string is already present */
		if (!isset($this->_str_table[$str])) {
			$this->_str_table[$str] = $this->_str_unique++;
		}
		$this->_str_total++;

		$header	= pack('vv',   $record, $length);
		$data	= pack('vvvV', $row, $col, $xfIndex, $this->_str_table[$str]);
		$this->_append($header.$data);
	}