The same physics that correctly predicted superconductivity ofPrBa2Cu3O7also explains flux pinning by Ba-site magnetic rare-earth ions in(rare-earth)1+uBa2−uCu3Oxcompounds withx≈7.The customary cuprate-plane picture of superconductivity must be revised in the same way to consistently explain the observations either of flux pinning or ofPrBa2Cu3O7superconductivity withTc≈90K. ©1997 American Institute of Physics.