The EU came fairly close to forcing Microsoft to open up the Office document formats as part of their string of antitrust actions against Microsoft. In the end

The EU came fairly close to forcing Microsoft to open up the Office document formats as part of their string of antitrust actions against Microsoft. In the end they did force Microsoft to open up the protocols used by Windows clients to communicate with Microsoft's own servers (to allow third party interoperability with server products like Samba), but did not do the same thing with the various Office document formats. After an additional $1.3 billion fine, Microsoft stopped dragging it's feet and complied with the ruling. https://www.computerworld.com/article/2537525/eu-fines-microsoft-another--1-3b.html https://www.computerworld.com/article/2537525/eu-fines-micro...