  In this dissertation, a complete calculation of QED radiative corrections is
presented for total cross sections and forward- backward asymmetries for
s-channel fermion pair production in e+e- annihilation with kinematical cuts to
the final state. This includes cuts on the maximal acollinearity angle
theta_acol and on the minimal energies E_min of the final state fermion pair
and on the cosine of the scattering angle of one fermion, cos{theta}. The
applied cuts pose a realistic alternative for leptonic final states compared to
cuts on the invariant mass squared s' of the fermion pair and on cos{theta}.
The new formulae and the analysis presented in this thesis for high energies
and luminosities form an essential building block for an upgrading of
two-fermion codes like ZFITTER for a future e+e- Linear Collider.
