  Theoretical model is presented to describe the anomalous ordered phase of Pr
ions in PrBa_2Cu_3O_(6+x) below T_Pr = 12-17 K. The model considers the Pr
multipole degrees of freedom and coupling between the Cu and Pr subsystems. We
identify the symmetry allowed coupling of Cu and Pr ions and conclude that only
an ab-plane Pr dipole ordering can explain the Cu spin rotation observed at
T_Pr by neutron diffraction by Boothroyd et al. [A. T. Boothroyd et al., Phys.
Rev. Lett. 78, 130 (1997)]. A substantial enhancement of the Pr ordering
temperature is shown to arise from the Cu-Pr coupling which is the key for the
anomalous magnetic behavior in PrBa_2Cu_3O_(6+x).
