Microsoft Excel 97-2003 Workbook (xls) 8 & 8X
Unknownspreadsheet · also known as Microsoft Excel Workbook (97-2000)
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.
Identify it
| Extensions | .xls.xlw |
|---|---|
| MIME types | application/vnd.ms-excel |
| PRONOM | fmt/61 |
| Wikidata | Q60886160 |
| Apple UTI | com.microsoft.excel.xls |
Not sure your file is this? Identify it from its first bytes, in your browser.
Open it
Convert it
No conversion recorded. One of the tools above may export it; search for a chain.
0Sources
From PRONOM, Wikidata. Updated 2026-10-20.