private function writeObjectProtect()
    {
        // Exit if sheet protection is not active
        if (!$this->phpSheet->getProtection()->getSheet()) {
            return;
        }

        // Exit if objects are not protected
        if (!$this->phpSheet->getProtection()->getObjects()) {
            return;
        }

        $record = 0x0063; // Record identifier
        $length = 0x0002; // Bytes to follow

        $header = pack('vv', $record, $length);
        $data = pack('v', 1);

        $this->append($header . $data);
    }