  Quasi-elastic scattering of the vector bosons W and Z is a sensitive probe of
the details of electroweak symmetry breaking, and a key process at future
lepton colliders. We discuss the limitations of a model-independent
effective-theory approach and describe the extension to a class of Simplified
Models that is applicable to all energies in a quantitative way, and enables
realistic Monte-Carlo simulations. The framework has been implemented in the
Monte-Carlo event generator WHIZARD.
