Calculated and observed line profiles, I/I_c (left-top panels), their residuals (as a percentage; left-bottom panels), and the corresponding bisectors (right panels) for four lines. The bisector curves were fitted using a sixth-degree polynomial (black and yellow curves) and the actual data (in gray) are shown. In the individual panels we show the Fe I 624 line (a), the Fe 1627 line (b), the Fe 1680 line (c), and Fe II 771 line (d).