About your second point, I just tested it on my machine, Word 2016 saves and opens *.odt files just fine. Is there some unsupported stuff?

Yes, their implementation is (deliberately?) patchy with many bugs. They've been lobbying to prevent governments from adopting ODF (an open ISO standard with multiple implementations): https://www.theregister.co.uk/2014/02/22/microsoft_uk_odf_re...

There's a nice documentary about Microsoft vs. FLOSS. https://www.youtube.com/watch?v=_wGLS2rSQPQ

What do you mean by 'wrapper over binary blobs'?

I know the old .doc format was basically a memory dump of the document; but how does OXML relate to that?

> OpenXML on the other hand, is a high-level specification which describes the high level envelopes used to embed binary objects which are included in the content. The content itself contains the binary code which can call any function in any Microsoft library and has all permissions of the person opening the document.

http://slated.org/ooxml_dissecting_the_binary_blob_problem http://ooxmlisdefectivebydesign.blogspot.com/2007/08/microso...

But lots of Office-like apps have implmented OpenXML read/write without MS libraries

They'll do it the day they think it's profitable for them to do so, as their public company status obliges them to do, unless their shareholders vote otherwise.

Of course. That's the point of criticizing them. So that they can see the potential profit in behaving nice.

Absolutely.