Arrangement of the positive and negative magnetic sources and the corresponding semilunar region of topological instability (yellow) in the GKSS model. Four color arrows (red, magenta, blue, and cyan) designate four different types of topological connectivity of the magnetic field lines between these sources. Various positions of the fourth magnetic source, x₄ = 1, 0.7, 0.4, 0.1, 0.0, −0.1, −0.4, −0.7, and −1.0, employed later, are shown by the black dotted circles.