  We present technical aspects of next-to-next-to-leading order calculations
for heavy-to-light decays such as top quark decay, semileptonic b quark decay
into a u quark, muon decay, and radiative decays like b -> s gamma. Algebraic
reduction of integrals to a set of master integrals is described, methods of
determining the master integrals are presented, and a complete list of master
integrals is given. As a sample application, the top quark decay width is
calculated to O(alpha_s^2) accuracy.
