Intensity (upper left panel), V/I (upper right panel), Q/I (lower left panel), and U/I (lower right panel) profiles as a function of wavelength. The various colored curves show the results of reference PRD calculations in which the magnetic field is fully taken into account in all RT coefficients (black curves), neglecting its impact only in the computation of the emission coefficient (red curves), and accounting for it only for η_I and ρ_V (blue curves). The magnetic field is horizontal (θ_B = 90°) with χ_B = 0° and has a strength of 50 G.