Microsoft Excel File Format

The binary interchange file format (BIFF) is the file format in which Microsoft Excel workbooks are saved on disk. Microsoft Excel versions 5.0 and later use compound files; this is the OLE 2 implementation of the Structured Storage Model standard. For more information on this technology, see the OLE 2 Programmer's Reference, Volume One, and Inside OLE 2, both published by Microsoft Press and available from your local bookstore.