  The properties of hard photon radiation in $W$ pair production at LEP 2 are
studied, with emphasis on the energy loss relevant to the W mass measurement.
We use a combination of the exact 1-photon matrix element and leading
logarithmic structure functions. Defining unobservable, observable and initial
state photons in the phase space, it is shown that neither the one-photon
matrix element nor the leading logarithmic structure functions alone give an
adequate description of the energy loss due to observable or initial state
photons. An event generator based on these calculations is available.
