A performance architect for a Fortune Fifty corporation deconstructed Microsoft's MS-OOXML specification for open documents and found many, many poor definitions and more just plain wrong formulas.
Rob Weir reports in his blog how Redmond allows mixing of radians and degrees in seven functions (remember the Mars Climate Lander, anyone?), doesn't define which units of measure with the same name (for an Imperial pint is not a U. S. pint, as any serious beer drinker can tell you) are used. Then, there are formulas that are clearly incorrect, like AVEDEV and ZTEST, as well as formulas which work OK Stateside but fail in the Middle East (NETWORKDAYS doesn't calculate well if the Sabbath starts at Friday sundown).
Maybe no one ever got fired for buying Microsoft software, but if you rely on its software, you just might crash... not just your PC, but your space probe. Weir dryly quotes a very relevant aphorism:
What do you call a scientist whose calculations are off by 50%? A cosmologist.
What do you call an accountant whose calculations are off by 1%? A crook.
Ironically, this revelation follows half a year of Microsofties' criticism of the alleged inadequacies of ODF. Given this revelation regarding the Emporer's New Algorithms, Free Software Foundation Europe has six simple questions regarding this proposal that seem eminently rational to ask, and I hope you agree.