Stokes I, normalized to the continuum intensity I_cont (first and third rows), and fractional linear polarization Q/I profiles (second and fourth rows), shown as a function of wavelength distance from the center of each line under consideration. The intensity profiles of the UV doublet and of the IR triplet lines are normalized to the continuum value at λ = 3954.8 Å and at λ = 8500.5 Å, respectively. The profiles were computed in the semi-empirical model C of Fontenla et al. (1993) assuming a 5L atomic model. The emergent profiles are shown at a line of sight with μ = 0.1. The various curves represent the results of different redistribution treatments: CRD (solid black), IRCRD (dashed red), and PRD (dotted blue). The reference direction for positive Stokes Q is the parallel to the nearest limb.