Windabs uses the 'sei' method of Lamers et al. 1987 Ap. J. 314 726 to take the line center optical depth calculated by the usual warmabs routines and spread them in wavelength space in order to model the scattering in an outflowing wind. Bound-free absorption is treated the same as in warmabs. For lines, the optical depths from warmabs are input to the sei routines as the value of the paramter ttot (optical depth normalization). The input velocity vturb is used as the terminal velocity of the wind. Other sei parameters are assumed to be fixed: gamma=1 (run of optical depth with velocity), apha=1 (velocity law), and eps=0 (thermalization parameter). Windabs has the same input parameters as warmabs, except that it also has a covering fraction parameter, (not part of the standard sei formulation), which should be in the range 0-2. The physical meaning of is that, when 01, the emission component is reduced by a factor of . A feature added on 09/04/2007: when covering fraction 1, the absorption component is reduced by a factor . So at , the model produces pure scattered emission. Values of 2 have no physical meaning.