Ownership has two principal special modes, co-ownership and superficies.
Co-ownership is ownership of the same property, jointly and at the same time, by several persons each of whom is privately vested with a share of the right of ownership. Co-ownership is called undivided where the right of ownership is not accompanied with a physical division of the property. It is called divided where the right of ownership is apportioned among the co-owners in fractions, each comprising a physically divided private portion and a share of the common portions. Superficies is ownership of the constructions, works or plantations situated on an immovable belonging to another person, the owner of the subsoil.