Small spectral section showing the intensity line variations in the secondary Ap component. Ticks correspond to the spectral lines Fe iiλ4541.5, Sm iiλ4537.9, and Sm iiλ4543.9. Arbitrary vertical shifts have been applied for clarity. The ordinate scale is 0.1 per tick. Orbital phases are labeled at the right side, increasing from bottom to top. The first curve is the standard deviation of the residual of the 11 spectra with respect to the mean spectrum of the secondary, scaled by a factor of 5 for better visibility.