Lens system configurations of the three degenerate 2L1S solutions: A, B_c, and B_w. In each panel, the blue dots, marked by M₁ (host) and M₂ (planet), are the lens positions, the line with an arrow is the source trajectory, and the cuspy closed curves are the caustics. The dashed circle centered at M₁ represents the Einstein ring. The enlarged views in the central magnification regions for the individual solutions are presented inFig. 5.