Dutch Digital Preservation Testbed, From digital volatility to digital permanence, part two: preserving spreadsheets (available at http://www.digitaleduurzaamheid.nl/bibliotheek/docs/volatility-permanence-spreadsh-en.pdf, accessed 26.11.2007).

DPT looks at the three basic migration routes. Backward compatibility is the most commonly used, such as using Excel 2003 to open a file created in Excel 97, and then saving it as a 2003 file. The filename extension .xls covers a lot of different formats, the one here for instance mentions specifically Excel 2.1, 3.0. 4.0, 5.0/95, 97-2000. Here’s a crib on some history of Excel: “When Microsoft unveiled the original Windows in 1987, Excel was one of the first products to be written for it, and even now many people still use Excel 2.1 which was written to run under Windows version 2. When Windows finally took off with Version 3.0 in late 1989, Excel was its flagship product. It remained the only Windows spreadsheet for nearly 3 years and only received any real competition from other products in the summer of 1992.” (from http://www.leeds.ac.uk/iss/documentation/beg/beg17/beg17-2.html accessed 27.11.2007).

Excel 2, BIFF2, Excel 2.0, 1987, worksheet
Excel 3, BIFF3, Excel 3.0, 1990, worksheet, workspace
Excel 4, BIFF4, Excel 4.0, 1992, worksheet and combined workbook/workspace
Excel 5, BIFF5, Excel 5.0, 1993, workbook or workspace
Excel 7, BIFF5, Excel 95, 1995, ditto
Excel 8, BIFF8, Excel 97, 1997, ditto. Major changes to how the binary data was stored, and number of rows went up from 16384 (2 to 14) to 65536 (2 to 16).
Excel 9, BIFF8, Excel 2000, 1999, ditto
Excel 10, BIFF8, Excel XP, 2001, ditto
Excel 11, BIFF8, Excel 2003, 2003, ditto.

BIFF really just a memory dump of how the data looks inside the application’s own memory.

Microsoft have often used Excel to promote new ideas and technologies. Excel 3.0 was the first major product to come out with a Toolbar, by which commonly-used commands can be quickly accessed. Excel 4.0 was the first main product to support the Object Linking and Embedding technology. Excel 5.0 was the first Microsoft application to support the Visual Basic for Applications Edition programming language.