a) Shaded surface of v_A(x,y,z₀) = | B₀(x,y,z₀) | in the xy-plane at z₀ = 0.1, with local maxima at (x,y,z) = ( ± a,0,0), i.e. the dipoles’ location. b) Colour contour of v_A(x,0,z) = | B₀(x,0,z) | in the y = 0, xz-plane. Contour is colour coded: 0 ≤ v_A ≤ 0.3 (white); 0.3 ≤ v_A ≤ 0.5724 (green); 0.5724 ≤ v_A ≤ 2 (yellow); 2 ≤ v_A ≤ 30 (orange); v_A ≥ 30 (black). Red lines indicate the separatrices in this plane. c) Colour contour of v_A(0,y,z) = | B₀(0,y,z) | in the x = 0, yz-plane. Blue line indicates the X-line in this plane. Contour is colour coded in the same way as b). d) Plot of | B_x(0,r) | = v_A(0,y,z) where r² + y² + z² and axis displays 0.5 ≤ r ≤ 2. Colour coding corresponds to that of b) and c), except now black represents | B_x(0,r) | ≤ 0.3.