Ahhhh. I am enlightened. Thank you for your explanation. It is now clear in my mind. I was thinking that .ODT was something like .PDF in that it will open in any type of office suite, MS Word, Word Perfect, MS Works (?), etc. Yes, I suppose I am a bit (not frustrated) but disappointed. I love my iMac and I love Libre Office and will continue to use both. What is your opinion of the Libre "start page" where when you open LO you are confronted with icons of recently opened documents. I can tell you that I absolutely don't like it. In Windows there is a very easy work-around for deactivating that page. I tried to do the same in mac but apparently the program files are named differently than windows and I didn't recognize which file was which. In other words, which file represents Calc, Write etc.