  We consider the superconformal index of class S theories of type D, which
arise by compactification of the (2,0) D_n theories on a punctured Riemann
surface C. We also allow for the presence of twist lines on C associated to the
Z_2 outer automorphism of D_n. For a two-parameter slice (p=0, q, t) in the
space of superconformal fugacities, we determine the 2d TQFT that computes the
index.
