1σ (marked areas) and 3σ (dotted lines) confidence regions of the tested SED parameters for test cases A (upper panels) and B (lower panels). The three left panels show the projections into each of the three possible planes, i.e. Δ₁ versus Δ₂, Δ₃ versus Δ₂, and Δ₁ versus Δ₃, respectively. The right panels show the enhancement of the intensity break at 3 Ryd compared to the HM01 background, which means Δ₁ − Δ₂, versus the strength of the 4 Ryd break Δ₃, where the dashed line indicates a linear fit of the correlation (see text). The parameters of the input SEDs are marked with stars.