Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xls/Workbook.php
private function writeCodepage()
    {
        $record = 0x0042; // Record identifier
        $length = 0x0002; // Number of bytes to follow
        $cv = $this->codepage; // The code page

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

        $this->append($header . $data);
    }
private function writeCodepage()
    {
        $record = 0x0042; // Record identifier
        $length = 0x0002; // Number of bytes to follow
        $cv = $this->codepage; // The code page

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

        $this->append($header . $data);
    }
Stores the CODEPAGE biff record.