  This thesis is concerned with the calculation of fixed moments of the
O(a_s^3) heavy flavor contributions to the Wilson coefficients of the structure
function F_2(x,Q^2) in the limit Q^2 >> m^2, neglecting power corrections. The
massive Wilson coefficients in the asymptotic region are given as convolutions
of massive operator matrix elements (OMEs) and the known light flavor Wilson
coefficients. The former derive from the twist--2 operators emerging in the
light--cone--expansion and are calculated at the 3--loop level for fixed
moments. We also compute the massive OMEs which are needed to evaluate heavy
flavor parton distributions in the variable flavor number scheme to the same
order. All contributions to the Wilson coefficients and OMEs but the genuine
constant terms at O(a_s^3) of the OMEs are derived in terms of quantities,
which are known for general values in the Mellin variable N. For the OMEs
A_{Qg}^(3), A_{qg,Q}^(3) and A_{gg,Q}^(3) the moments N = 2 to 10, for
A_{Qq}^{(3), PS} to N = 12, and for A_{qq,Q}^{(3), NS}, A_{qq,Q}^{(3), PS},
A_{gq,Q}^(3)}to N=14 are computed. These terms contribute to the light flavor
'+'-combinations. For the flavor non-singlet terms, we calculate as well the
odd moments N=1 to 13, corresponding to the light flavor '-'-combinations. We
also obtain moments of the terms ~ T_F of the 3-loop anomalous dimensions in an
independent calculation, which agree with results given in the literature. The
mathematical structure of the occurring momentum integrals and of the final
results in terms of harmonic sums is discussed. We study applications of the
same techniques to the polarized and transversity case at the NLO and NNLO
level as well.
