I've never seen this before in my life:
I downloaded my professor's programming notes and all the PowerPoints have a little "lock" icon on them. Presentations I make myself don't.
What's it mean? I seem to be able to edit and save over them just fine, I'm just curious why they have a lock over them.
Oh, and as far as "security" goes, it seems all the users have full permission.
I did download these using Firefox, but it seems ONLY pptx files have a lock, mp3s, jpegs, whatever else doesn't.