In his analysis, Mahugh came to the opposite conclusion: Excel 2007 actually rendered results from an OpenOffice.org-created spreadsheet more correctly than Lotus Symphony did.

Microsoft and IBM have been trading barbs on document format standards for half a decade, since Microsoft first announced plans to create an XML-based document format for Office 2007. In reaction, of the ODF standard by global standards bodies such as ISO and OASIS in 2006.

That led to Microsoft's successful push to get its document format, now called Office Open XML (OOXML), to by the same standards bodies two years later.

Rather than taking sides in this squabble, Guy Creese, an analyst with Burton Group, blames the data corruption problems in ODF on the reluctance of standards makers to strictly define the spreadsheet formulas when ODF was first approved.

ODF 1.2 will finally do that, but in the meantime, others supporting ODF, such as Google Inc. and its Google Docs, had followed OpenOffice.org's de facto example. Perhaps naturally, Microsoft was reluctant to join that camp.