I would have thought everyone knew this.

I just want to say one thing: If you're going to work on a door that opens inward - i.e. TOWARDS you - you should put a sign on the door so no one opens it when you're up on the ladder. Because if you don't you could get hurt and it WOULDN'T be the fault of the door opener. I guess that is two things. But still, people need to do this.