As I have said many times in the past I used to write document conversation tools. I believe this gives me a valid reason to be able to pass comment on the ODF/OOMXL debate that is raging at the moment. If these types of questions interest you, have a look at the book I talk about later ( In Search of Stupidity: Over 20 Years of High-Tech Marketing Disasters (UK) or here for US link ) Lets start with some history about the Office 97-2003 file formats. Joel was writing about this today ( Why are the Microsoft Office file formats so complicated? (And some workarounds) - Joel on Software ). Note that part of what he has commented on is the fact that the documentation for the binary file format is now available from Microsoft: Why are the Microsoft Office file formats so complicated? (And some workarounds) This item ran on the Joel on Software homepage on Tuesday, February 19, 2008 Last week, Microsoft published the binary file formats for Office . These formats appear to be almost completely insane. The Excel 97...