I don't understand what you mean by "self relation" or relating objects "to" others. Relations are objects themselves, with tags, that contain other objects. Each child of a relation has a role. A building relation is supposed to have all of the tags for the building, and have all of the building parts as children, with the role "part." A building relation is also supposed to have a building way with the role "outline," and that seems to have been the only error.