D-branes in an asymmetric orbifold
  We consider the asymmetric orbifold that is obtained by acting with T-duality on a 4-torus, together with a shift along an extra circle. The chiral algebra of the resulting theory has non-trivial outer automorphisms that act as permutations on its simple factors. These automorphisms play a crucial role for constructing D-branes that couple to the twisted sector of the orbifold. 
Matthias R Gaberdiel, Sakura Schafer-Nameki