682 Microsoft Excel 5.0/95 Workbook (xls) 5/95 Microsoft Excel Workbook (5.0) Spreadsheet None The Binary Interchange File Format (BIFF) is a spreadsheet file format developed by Microsoft. BIFF 5 is a native file format of Microsoft Excel 5.0 for Windows. 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. From Excel 5.0 onwards, BIFF 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. 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/59 PUID xlw File extension xls File extension Has lower priority than 684 Microsoft Excel 97 Workbook (xls) Has priority over 767 OLE2 Compound Document Format Is subsequent version of 680 Microsoft Excel 4.0 Worksheet (xls) Is subsequent version of 681 Microsoft Excel 4.0 Workbook (xls) Is subtype of 767 OLE2 Compound Document Format