Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xls/Parser.php
private function convertRef3d($cell)
    {
        // Split the ref at the ! symbol
        list($ext_ref, $cell) = explode('!', $cell);

        // Convert the external reference part (different for BIFF8)
        $ext_ref = $this->getRefIndex($ext_ref);

        // Convert the cell reference part
        list($row, $col) = $this->cellToPackedRowcol($cell);

        // The ptg value depends on the class of the ptg.
        $ptgRef = pack('C', $this->ptg['ptgRef3dA']);

        return $ptgRef . $ext_ref . $row . $col;
    }
private function convertRef3d($cell)
    {
        // Split the ref at the ! symbol
        list($ext_ref, $cell) = explode('!', $cell);

        // Convert the external reference part (different for BIFF8)
        $ext_ref = $this->getRefIndex($ext_ref);

        // Convert the cell reference part
        list($row, $col) = $this->cellToPackedRowcol($cell);

        // The ptg value depends on the class of the ptg.
        $ptgRef = pack('C', $this->ptg['ptgRef3dA']);

        return $ptgRef . $ext_ref . $row . $col;
    }
Convert an Excel 3d reference such as "Sheet1!A1" or "Sheet1:Sheet2!A1" to a
ptgRef3d.

@param string $cell An Excel cell reference

@return mixed the packed ptgRef3d token on success