PhpSpreadsheet Reading WorkBook Data Example #02
        Read a list of Custom Properties for a WorkBook
        load($inputFileName);
        echo '
';
        /*  Read an array list of any custom properties for this document  * */
        $customPropertyList = $spreadsheet->getProperties()->getCustomProperties();
        echo 'Custom Property names: 
';
        foreach ($customPropertyList as $customPropertyName) {
            echo $customPropertyName, '
';
        }
        ?>