Determination of Ṁ for HD 156292 from the UV lines. The IUE spectrum is in black. We show the models in green (lower limit on Ṁ), red (final model), and blue (upper limit on Ṁ). Mass-loss rate unit is in M_⊙ yr⁻¹. We note that Si IV λλ1394,1403 and C IV λλ1548,1551 are the most useful lines for the analysis of the wind mass loss in late O giants. All the models have v_∞ fixed in 1300 km s⁻¹.