I could have sworn this had been suggested already, but I couldn’t find a thread for it…
Currently, protection signs are only useful to protect a 31x31 area from all non-admin users and the owner. While this is great, it makes protection signs useless if world modification is set to “admin only”.
Permission signs would let world owners set the world to admin only modification, and then assign plots to players one by one. This would especially be useful in worlds like Kepler - where you need to be assigned a plot to build (near spawn)
Additionally, if no name was placed on the sign, any player would be able to modify blocks within it’s radius.