LOCATION OF HOLES IN Y1-XPRXBA2CU3O7

Recent experiments by Merz er al. [Phys. Rev. B 55, 9160 (1997)] demon strated that the loss of superconductivity upon Pr doping is associate d with the change of the character of the oxygen holes from p(sigma) t o p(pi). This experiment sheds light onto the long-standing problem of T-c suppression by Pr, and helps to rule out a number of theoretical models, leaving only those which predict such a transfer of the O hole s. To distinguish between the two models that do predict such an effec t, one has to access the ratio of the planar and axial character of th e holes. We do so in this paper.