The description of
annihilation into hadronic events involves a
number of components: the 
dependence of the total cross section
and flavour composition, multiparton matrix elements, angular
orientation of events, initial-state photon bremsstrahlung
and effects of initial-state electron polarization.
Many of the published formulae
have been derived for the case of massless outgoing quarks. For each
of the components described in the following, we will begin by
discussing the massless case, and then comment on what is done to
accommodate massive quarks.