  We consider the possibility that one extra $Z\equiv Z'$ exists with a mass of
more then two TeV and fermion couplings that do not violate (charged) lepton
universality. We show that, in such a situation, a functional relationship is
generated between the \underline{deviations} from the SM values of three
leptonic observables of two-fermion production at LC 2000 that is completely
independent of the values of the $Z'$ mass and couplings. This selects a
certain region in the 3-d space of the deviations ($Z'$ "reservation") that is
\underline{characteristic} of the model and that would have no observable
intersection with analogous regions corresponding to other interesting models
of new physics.
