Diagnostic sensitivities for three limits of the ratio B_*/B_Hanle. This figure presents a summary of how our theoretical results may be used to derive the magnetic properties of a stellar envelope. Plotted is the normalized line polarization (as in Figs. 5 and 6) as a function of B_*/B_Hanle for a fictitious field distribution (shown only for reference). The space is divided into three regions, corresponding to B_*/B_Hanle 1 (left), B_*/B_Hanle ~ 1 (middle), and B_*/B_Hanle 1 (right). As discussed in the text and as indicated in the figure, the regimes of (1) small B_*/B_Hanle ratios provide information about the envelope density distribution, (2) large B_*/B_Hanle ratios give an indication of the vector magnetic field geometry, and (3) B_*/B_Hanle ratios near 1 are useful for deriving the surface field strength.