Model-independent determination of $Z'$ couplings at LEP 200
  All couplings of a new heavy gauge boson to ordinary fermions can be determined in a model-independent way at a large $e^+e^-$ collider for large enough statistics. No such determination is possible at LEP 200, however, because its design integrated luminosity is too low for existing and forthcoming limits on $Z'$ interactions. At any rate, it should be possible to distinguish between models for $Z'$ masses $< 1\ TeV$, or to set limits of this order on $Z'$ masses for definite models. These are (preliminary) $1\sigma $ limits. We neglect systematic errors and assume an integrated luminosity of $0.5\ fb^{-1}$. 
F. del Aguila