Six representative CAFOS spectra. From top to bottom, spectra of standard stars with spectral type 1.0 and 0.5 subtypes earlier than the target (black), standard star with the same spectral type as the target (cyan), the target star (red; in this case, J04393+335 – M4.0 V, Simbad name: V583 Aur B), and standard stars with spectral type 0.5 and 1.0 subtypes later than the target (black). We mark activity-, gravity-, and youth-sensitive lines and doublets at the top of the figure (Hγ, Hβ, He i D₃, Na i D₂ and D₁, Hα, Li i, K i, and Na i, from left to right) and molecular absorption bands at the bottom. Note the three first lines of the Balmer series in emission in the spectrum of the target star.