Heavy Flavor Contributions to DIS Structure Functions at $O(\alpha_s^3)$

We calculate moments of the $O(\alpha_s^3)$ heavy flavor contributions to the Wilson coefficients of the structure function $F_2(x,Q^2)$ in the region $Q^2\gg m^2$. The massive Wilson coefficients are obtained as convolutions of massive operator matrix elements (OMEs) and the known light flavor Wilson coefficients. The calculation of moments of the massive OMEs involves a first independent recalculation of moments of the fermionic contributions to all 3--loop anomalous dimensions of the unpolarized twist--2 local composite operators stemming from the light--cone expansion. The expressions for the massive OMEs are now known for general values of the Mellin variable $N$ apart of one coefficient in the constant term, for which only a series of moments is computed.