“…where (fS, f T, f b 1 , f b 2 , fq), with (S, T, b 1 , b 2 , q) all constants, are the corresponding distortion characteristics. These equations are equivalent versions, fit to the present purpose, of the compatibility conditions considered in [19]. As for using them as sufficient conditions to determine quasi-uniform distortions, the same caveats issued in [19] also apply here, as witnessed by the limited use we make of them.…”