Intensity (left column), Q/I (middle column), and U/I (right column) as a function of vacuum wavelength for the Mg II h&k doublet (first row) and the H I Ly-α line (second row), obtained with PRD–AD calculations in a static magnetic FAL-C atmosphere (see text) for a LOS with µ = 0.1. The solid black curves correspond to reference calculations, whereas the red (dashed), yellow (dot-dashed), and purple (dotted) lines are the results of calculations with increased spatial, angular, and frequency resolution, respectively. The reference direction for positive Stokes Q is the parallel to the limb.