Top panel: the CFLD_DI for the 1D-RSG model (Table 1). Middle panel: the depth function D (λ) ≡ log τ₀ (CFLD_max (λ)) corresponding to the crest line of the CFLD in the λ − log τ₀ plane. Star symbols correspond to minima of the depth function. The horizontal bands represent the log τ₀ ranges spanned by the different masks. The horizontal blue line identifies the spectral interval of the displayed CFLD (top panel). Bottom panel: the corresponding synthetic spectrum.