Office documents since the 2007 have used a zipped XML approach. Just take an .docx and open it in 7zip.
EDIT: Narrowed the date.
Office documents since the 2007 have used a zipped XML approach. Just take an .docx and open it in 7zip.
EDIT: Narrowed the date.
I’m aware. IIRC this was a response to Microsoft being forced to use some “open” protocol or something.