(a) The declustered subsets of PKP(AB-DF) differential travel time residuals used in this study. Different symbols, corresponding to data from different analysts are explained in the legend. Residuals are calculated with respect to the ak135 model (Kennett et al., 1995) and plotted with respect to the angle $\xi$ between the PKP(DF) leg in the inner core and the rotation axis of Earth. Standard ellipticity corrections were applied. All earthquake locations and origin times are corrected with respect to the relocation catalog of Engdahl et al., 1998. Some specific polar paths are indicated by numbers as follows: 1) Svalbard Sea to SPA; 2) 63N,143W to SPA; 3) 79N,124E to SPA; 4) 67N,173W to SPA; 5) 60N,153W to SPA; 6) mid-Atlantic ridge to Alaska; 7) South Sandwich Islands to COL; 8) South Sandwich Islands to BILL; 9) South Sandwich Islands to SEY; 10) southeast Pacific to NRIL; 11) South Sandwich Islands to COL and NRIL; 12) mid-Atlantic ridge to Alaska; 13) south of New Zealand to FRB; 14) Bouvet Islands to COLA and INK; 15) Aleutian Islands to SYO; 16) Sea of Okhotsk to SYO; 17) south of New Zealand to KBS; 18) various locations to SYO; 19), 20) and 21) Aleutian Islands to SYO. (b) Same as (a), where circles and pluses correspond to paths for which PKP(DF) bottoms in the quasi-western and quasi-eastern hemisphere, respectively, as defined by Tanaka and Hamaguchi (1997).