684 Microsoft Excel 97-2003 Workbook (xls) 8 & 8X Microsoft Excel Workbook (97-2000) Spreadsheet None The Binary Interchange File Format (BIFF) is a spreadsheet file format developed by Microsoft. BIFF 8 is a native file format of Microsoft Excel 97. 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 8 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 2000. Binary Little-endian (Intel) 1 Digital Preservation Department / The National Archives 11 Mar 2005 This format can be identified via a container signature in DROID version 6 or later. The PRONOM database cannot currently represent container signatures. 18 Dec 2012 application/vnd.ms-excel MIME com.microsoft.excel.xls Apple Uniform Type Identifier fmt/61 PUID xls File extension xlw File extension Has lower priority than 44 Microsoft Excel Template Has lower priority than 1706 Microsoft Works Spreadsheet Has priority over 682 Microsoft Excel 5.0/95 Workbook (xls) Has priority over 767 OLE2 Compound Document Format Is previous version of 685 Microsoft Excel 2000-2003 Workbook (xls) Is subsequent version of 683 Excel 95 Workbook (xls) Is subtype of 767 OLE2 Compound Document Format