"Microsoft is way too smart to let the ecosystem suspect of a potential issue with document formats based on a specific obstacle built into the standard. For instance, it took quite a long time to spot the C-Font trick built into the last versions of MS Office, and most users – including corporate IT managers – are still completely unaware of it."

Why you should never use Microsoft's OOXML pseudo-standard format

The UK government recently announced that they would use ISO approved document standard ODF for viewing and sharing government documents. It's a very important move because it breaks Microsoft's vendor lock where single US-based company 'owns' and 'controls' all the documents created on Earth.