ODF also gained more support among word-processing applications from major technology vendors, Marcich said. Google Docs, Adobe Buzzword and OpenOffice.org's desktop and portable applications all now support ODF as a file format.

On the contrary, "I can count on my left hand how many .docx's I've received," he said, referring to the file extension for default Office 2007 files. However, to be fair, the OOXML/.docx implementation in Office 2007 differs from current OOXML specification, which has been altered through the standards process and is now known as ECMA 376.

Still, it's true that the default file format for exchanging most Office documents now is .doc, the default binary document file extension for Office before Office 2007. Even Marcich acknowledged that "the old binaries dominate the landscape" right now.

Unlike Marcich, Microsoft still believes there is room for more than one XML-based file format, said Dough Mahugh, a Microsoft senior program manager for Office interoperability, in an e-mail Tuesday.

"Microsoft is committed to interoperability, transparency and user choice," he said. "That is why we are supporting additional formats going forward; after all, users have always wanted access to multiple formats, and now they have even more options."