The main facts concerning the dependence of superconductivity on rare-
earth ion R in the homologues of RBa2Cu2NbO8, RBa2Cu3O7, RBa2Cu4O8, R2
-zCezCuO4, and R2-zCezSr2Cu2NbO10 are organized using the principles t
hat the supercurrent is where the holes are and the superconducting co
ndensate is beyond the pair-breaking range of active rare-earth magnet
ic moments. Experiments to test this organization are proposed. (C) 19
97 American Institute of Physics. [S0021-8979(97)08223-6].