private function _writeDefinedNameBiff8($name, $formulaData, $sheetIndex = 0, $isBuiltIn = false)
	{
		$record = 0x0018;

		// option flags
		$options = $isBuiltIn ? 0x20 : 0x00;

		// length of the name, character count
		$nlen = PHPExcel_Shared_String::CountCharacters($name);

		// name with stripped length field
		$name = substr(PHPExcel_Shared_String::UTF8toBIFF8UnicodeLong($name), 2);

		// size of the formula (in bytes)
		$sz = strlen($formulaData);

		// combine the parts
		$data = pack('vCCvvvCCCC', $options, 0, $nlen, $sz, 0, $sheetIndex, 0, 0, 0, 0)
			. $name . $formulaData;
		$length = strlen($data);

		$header = pack('vv', $record, $length);

		return $header . $data;
	}