Renormalizability and the model independent observables for abelian Z' search

The observables useful for the model independent search for signals of the abelian Z' in the processes e^+ e^- \to {\bar f}f are introduced. They are based on the renormalization group relations between the Z' couplings to the Standard Model particles developed recently and extend the variables suggested by Osland, Pankov and Paver. The bounds on the values of the observables at the center-of-mass energy \sqrt{s} = 500GeV are derived.