Spine polarization angle as a function of inclination. The individual panels represent the background emission (left), foreground emission (middle), and net sum (right). The location of the true light cylinder is given by a black dashed line, and the predictions of Equation (34) for ﹩{\tilde{R}}_{{\rm{spine}}}﹩ (the location where EVPA = ±45°) are plotted as face-up triangles for the background emission and face-down triangles for the foreground emission. In all cases, we see that Equation (34) is an excellent prediction for the location of the polarization swing. As inclination is increased, the location of the polarization swing begins to align with the true light cylinder. On the curves of the right panel, we include both the face-up and face-down triangles, respectively giving the predictions for both the background and foreground swing locations. The location where the net EVPA = 45° lies roughly between these two estimates.