{
 "id": "microsoft-excel-4-0-workbook-xls-4w",
 "name": "Microsoft Excel 4.0 Workbook (xls)",
 "category": "spreadsheet",
 "identifiers": {
  "extensions": [
   "xlw"
  ],
  "puid": [
   "fmt/58"
  ],
  "wikidata": [
   "Q63036234"
  ],
  "mime": [
   "application/vnd.ms-excel"
  ],
  "uti": [
   "com.microsoft.excel.xls"
  ],
  "magic": [
   {
    "offset": 0,
    "hex": "09040600",
    "notes": "BIFF 4 Workbook/Workspace"
   }
  ],
  "signatures": [
   {
    "name": "BIFF 4 Workbook/Workspace",
    "sequences": [
     {
      "position": "bof",
      "offset": 0,
      "pattern": "09040600(0000|0004)0001"
     }
    ]
   }
  ]
 },
 "status": "unknown",
 "summary": "The Binary Interchange File Format (BIFF) is a spreadsheet file format developed by Microsoft. BIFF 4W is a native file format of Microsoft Excel 4.0 for Windows. Excel 4.0 allowed either a single worksheet to be stored as a worksheet file (BIFF 4S), or for multiple worksheets to be combined in a single workbook file (BIFF 4W). The format is proprietary and Microsoft does not make details of its structure public. The information contained here is derived primarily from OpenOffice.org's reverse-engineered documentation of the format, and should not therefore be regarded as definitive. BIFF is a stream based format, and a BIFF 4W file comprises a Workbook Globals Substream, containing a Beginning of File (BOF) record, one or more embedded Worksheet streams (in BIFF 4S format), and terminated by an End of File (EOF) record.",
 "tools": [
  {
   "name": "MediaRich Server",
   "url": "https://equilibrium.com/mediarichserver/",
   "reads": true,
   "writes": false
  },
  {
   "name": "Microsoft Office Excel 2007",
   "url": "https://www.wikidata.org/wiki/Q10329635",
   "reads": true,
   "writes": false
  }
 ],
 "projects": [
  {
   "name": "PRONOM fmt/58",
   "url": "https://www.nationalarchives.gov.uk/PRONOM/fmt/58",
   "kind": "format-doc"
  },
  {
   "name": "Wikidata Q63036234",
   "url": "https://www.wikidata.org/wiki/Q63036234",
   "kind": "wiki"
  }
 ],
 "provenance": {
  "sources": [
   "pronom",
   "wikidata"
  ]
 },
 "updated": "2026-10-20",
 "version": "4W",
 "aliases": [
  "Microsoft Excel Workbook (4.0)"
 ],
 "structure": [],
 "parsers": [],
 "conversions": [],
 "samples": [],
 "claims": [],
 "verification": [],
 "family": "microsoft-excel"
}