However the MMS prescription for calculating twisted K-theory is easily S-covariantized, as the Freed-Witten anomalies respect S-duality. Thus the S-covariantized form of the MMS construction may be applied to construct the S-covariantized twisted K-theory, as a set, without knowing having any geometric description for just what this strange covariant object is. This program has been carried out in a number of papers, such as and , and was also applied to the classification of fluxes by . use this approach to prove Diaconescu, Moore, and Witten's conjectured constraint on the 3-fluxes, and they show that there is an additional term equal to the D3-brane charge. shows that the Klebanov-Strassler cascade of Seiberg dualities consists of a series of S-dual MMS instantons, one for each Seiberg duality. The group, formula_1 of universality classes of the formula_6 supersymmetric gauge theory is then shown to agree with the S-dual twisted K-theory and not with the original twisted K-theory.