685 Microsoft Excel 2000-2003 Workbook (xls) 8X Microsoft Excel Workbook (XP-2003), Microsoft Excel Workbook (2002-2003) Spreadsheet None The Binary Interchange File Format (BIFF) is a spreadsheet file format developed by Microsoft. BIFF 8X is a native file format of Microsoft Excel XP. The format is proprietary and Microsoft does not make details of its structure public. The information here is derived primarily from OpenOffice.org's reverse-engineered documentation of the format and should not therefore be regarded as definitive. BIFF 8X is based on Microsoft’s generic OLE2 Compound Document Format. An Excel workbook is stored as a ‘Book’ stream within a Compound Document Format file. The Book stream comprises a Workbook Globals Substream, containing a Beginning of File (BOF) record, the Workbook global records, and terminated by an End of File (EOF) record. This is followed by one or more Worksheet substreams, containing a Beginning of File (BOF) record, the worksheet records, and terminated by an End of File (EOF) record. The format remained unchanged with the release of Excel 2003. Binary Little-endian (Intel) 1 Digital Preservation Department / The National Archives 11 Mar 2005 02 Aug 2005 com.microsoft.excel.xls Apple Uniform Type Identifier fmt/62 PUID Has priority over 767 OLE2 Compound Document Format Is subsequent version of 684 Microsoft Excel 97-2003 Workbook (xls) Is subtype of 767 OLE2 Compound Document Format