Excel an XML format

An example:

    <?xml version="1.0"?>
    <?mso-application progid="Excel.Sheet"?>
    <Workbook
        xmlns:x="urn:schemas-microsoft-com:office:excel"
        xmlns="urn:schemas-microsoft-com:office:spreadsheet"
        xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet">
        <Worksheet ss:Name="Sheet1">
            <Table ss:ExpandedColumnCount="2" ss:ExpandedRowCount="4">
                <Row ss:Index="4">
                    <Cell ss:Index="2">
                        <Data ss:Type="String">hello, world</Data>
                    </Cell>
                </Row>
            </Table>
        </Worksheet>
    </Workbook>