goal precludes the use of more sophisticated models. Rotationally broadened $IUE$ Si[iv]{} spectra of B dwarfs were used as the photospheric input to the SEI models. (A TLUSTY plane-parallel model atmosphere spectra (e.g. Hubeny [&]{} Lanz, 1995) was adopted for the SMC star AV264.) We assume a standard “$\beta$-law” for the expansion of the wind, and set (for $w$ = $v/v_\infty$) the initial velocity $W_0$ = 0.01 and the extent of the optical depth for resonance lines $W_1$ = 1. A non-linear least squares procedure is used to match the wind profiles, with the velocity law index ($\beta$) and turbulent velocity parameter ($v_{\rm turb}$) also allowed to vary. Generally in order to match the NACs well there was a tendency for $v_\infty$ to be placed very close to the shortward edge of the profile with low values of $v_{\rm turb}$. The adopted SEI model fitting parameters are listed in Table 2.

Examples of the independent SEI line profile matches to red and blue Si[iv]{} doublet components are shown in Fig. 1, where we also plot the corresponding values for $\tau_{\rm{rad}}(w)$. The models generally match the observed absorption very well for the NAC region and at low velocities (typically down to 