> The two office suites take very different paths here. LibreOffice uses the OpenDocument Format (ODF), an open standard meant to be controlled by no single company. Microsoft, on the other hand, created its own Office Open XML (OOXML) to support every feature in its own software, giving us the familiar .docx and .xlsx

It's so impressively underhandedly sneaky that Microsoft named their ODF-competitor format “Office Open” just as OpenOffice.org's (LibreOffice's direct ancestor) hype peaked with OO.o 2.0 having ODF as its native format, when MS Office finally had a viable and popular competitor for like the first time ever.

https://www.openoffice.org/press/2.0/press_release.html (2005-10-20)

https://news.microsoft.com/2005/11/21/qa-microsoft-co-sponso... (2005-11-21)