ECMA 376 is explicitly intended as documentation of what Office 2007 does. Michael Meeks of LO (then at Novell) worked on it and says it did this job: https://p

ECMA 376 is explicitly intended as documentation of what Office 2007 does. Michael Meeks of LO (then at Novell) worked on it and says it did this job: https://people.gnome.org/~michael/blog/2014-02-26-cabinet-office.html#tc45 https://people.gnome.org/~michael/blog/2014-02-26-cabinet-of... But in practice there's no such thing as "OOXML" - there's only what Office 2007, 2008, 2010, 2011, 2013 and 2016 happen to do. So if you want to work with the stuff, you verify everything. The standard is, like so much Microsoft documentation, best treated as based-on-a-true-story fiction with an unreliable narrator.