  We study a special combination of the compact directions of the spacetime
(compactified on tori) and the worldsheet parity transformed of these
directions. The transformations that change the compact part of the spacetime
to this combination, are more general than the T-duality transformations. Many
properties of this combination and also of the corresponding worldsheet
fermions are studied. By using the boundary state formalism, we study the
effects of the above transformations to D-branes. For the special cases the
resulted branes reduce to the known mixed branes, or reduce to the modified
mixed branes.
