Model spectra for accretion disks with different extensions, compared to the observation (black line). Shown are the changes of the inner edge (top left panel), the outer edge (right), and simultaneous changes (bottom) under i = 40   °. The given numbers correspond to the disk rings in Fig. 1. For clarification, the computed spectra are shifted vertically (from top to bottom; top panels: −0.03, −0.06, −0.09; bottom panel: + 0.05, 0.00, −0.05).