As a result, no OOXML document can be opened in non-MS Office software and get the same result. In fact, Word/Excel documents created in the Windows version can barely be opened in MS Office for OS X, because the OS X version is always lagging behind, always lacking features, like macros. I routinely got and still getting Word/Excel documents that I can't view in MS Office on OS X or in LibreOffice in Linux, because users can't help themselves in using totally useless features and also can't be convinced to use more portable formats, because in their worldview, what could be more standard than MS Office?
OOXML is Microsoft's response to ODF - they released it because governments started worrying about keeping their data in binary formats. But make no mistake, OOXML is just a farce, meant to sidetrack a real standard from happening.