Natural logarithm of the ratio of the line strength S in the Babushkin form to the line strength S in the Coulomb form, as a function of the G_{S = 0} parameter. The figures show the results of present transition calculations (each dot represents a certain transition). Panel (a) shows three distinct parts, each plotted on a separate graph: (1) the upper part of the graph (blue points), where − ∞ <G_{S = 0} < 0 (or part b); (2) the lower left part of the graph (red points), where (or part c); and (3) the lower right part of the graph (green points), where (or part d).