"An Exterior, Surface, Boundary, and Interior are picked out relative to the Ground. This Ground may either occupy only the Boundary (in which case the Interior is negative space) or the Ground may fill the Interior."@en . . . . . . . . . . . . . . . "Bounded_region" . "2019"^^ . "2008-02-25T15:52:34+01:00"^^ . .