ExcelTemplate.xml

<?xml version="1.0" encoding="utf-8" ?> 
<?mso-application progid="Excel.Sheet" ?>
<Workbook xmlns="urn:schemas-microsoft-com:office:spreadsheet"
          xmlns:o="urn:schemas-microsoft-com:office:office"
          xmlns:x="urn:schemas-microsoft-com:office:excel"
          xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet"
          xmlns:html="http://www.w3.org/TR/REC-html40">
  <Worksheet ss:Name="Sheet1">
     <Table>
       $ROWSPLACEHOLDER$
     </Table>
  </Worksheet>
</Workbook>