private function _readTertiaryOPT()
	{
		// offset: 0; size: 2; recVer and recInstance

		// bit: 4-15; mask: 0xFFF0; recInstance
		$recInstance = (0xFFF0 & PHPExcel_Reader_Excel5::_GetInt2d($this->_data, $this->_pos)) >> 4;

		$length = PHPExcel_Reader_Excel5::_GetInt4d($this->_data, $this->_pos + 4);
		$recordData = substr($this->_data, $this->_pos + 8, $length);

		// move stream pointer to next record
		$this->_pos += 8 + $length;
	}