ORIENTED SHELL
Definition
An object is a <ORIENTED SHELL> if and only if: it is a <TOPOLOGY SHELL>; there exists a <MANIFOLD VOLUME> such that: for any point within the <MANIFOLD VOLUME>, there exists an oriented_manifold_shell that is within the <MANIFOLD VOLUME> and that lies between the point within the <MANIFOLD VOLUME> and the boundary. for each point within the <ORIENTED MANIFOLD SHELL> the neighbouring point within the <ORIENTED SHELL> has the same sense