We study open and unoriented strings in a Topological Membrane (TM) theory
through orbifolds of the bulk 3D space. This is achieved by gauging discret
e symmetries of the theory. Open and unoriented strings can be obtained fro
m all possible realizations of C, P and T symmetries. The important role of
C symmetry to distinguish between Dirichlet and Neumman boundary condition
s is discussed in detail.