Background-substracted LETGS ± 1 0.1−10 keV spectrum of Ark 564, with the best-fit hard power law and the addition of two black bodies (the PL_hard+2BB model). The upper panel shows the data with the convolved model in red (BW v. as a solid line). Below, the ratio data/model. The lower panel shows the flux spectrum with the composed physical model (and its components separately) as a solid line.