I’ve seen plenty of inventive hold-open devices on fire-rated doors, but I’ve never seen instructional signage to go along with them! Coincidentally, I received photos of a chain hold-open and the signage for a chain hold-open on the same day from two different people. The photos are not from the same facility or even the same country for that matter.
Maybe I’m naive, but in some cases I think people don’t even realize that they’re compromising life safety for the sake of convenience when they make these modifications. Even more evidence of why the annual inspection of fire doors is a positive step forward.