You can find information about the Excel file spec at Microsoft.com (msdn probably) or at openoffice:
http://sc.openoffice.org/excelfileformat.pdf http://www.microsoft.com/interop/docs/OfficeBinaryFormats.mspx http://download.microsoft.com/download/0/B/E/0BE8BDD7-E5E8-422A-ABFD-4342ED7AD886/Excel97-2007BinaryFileFormat(xls)Specification.pdf Good luck!
