  The electroweak O(alpha) contribution to the resonant single W production in
a general 4-fermion process is discussed with particular emphasis on a gauge
invariant decomposition into a QED-like and weak part. The cross section in the
vicinity of the resonance can be represented in terms of a convolution of a
`hard' Breit-Wigner-cross section, comprising the (m_t,M_H)-dependent weak
1-loop corrections, with an universal radiator function. The numerical impact
of the various contributions on the W line shape are discussed, together with
the concepts of s-dependent and constant width approach. Analytic formulae for
the W decay width are also provided including the 1-loop electroweak and QCD
corrections.
