rulie
Head Pro
When I'm marking a course for competitions, I will paint the area with white paint, and then paint a large "NPZ" just outside the area. If the area is large, more "NPZ" may be required. It is also included in the Notice to Players.I think if a club has a No Play Zone, and as a player you do not know it is a No Play Zone when you find your ball in it, then I'm guessing the failure is with the Club Committee in not making it clear, rather than you as the golfer. If it just has a white ring around it, like any other area of land that is marked GUR in the same way, then you'd be forgiven in thinking it is GUR as well.
One would expect similar markings and/or communication for club play, competition or not. There's obviously a reason for making it a NPZ and that reason needs to be respected!