alright, so i built a field cairn to protect my extended farm from my fellow villagers. one of them was just trying to cross the area and found out that he can get inside by the bottom of the area but not from the sides. if he tries from the sides, he'll get a message saying he can. if he enters through the bottom of the area, no message and he can walk freely. maybe it's a bug? he still can't do anything else, just walk. but just not on the edges on the side.
also, just noticed the field cairn can also be used to extend the vclaim? because mine did. the 30x30 area i claimed with it is a tile larger to one of the sides than the vclaim. i wasn't meaning to expand, just didn't want anyone touching my crops.