  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
$0.5\ fb^{-1}$.
