Fundamental vibration rotation CO lines at 4.67 μm and response functions. Left panels: synthetic CO lines (solid lines) and FoV average (dotted lines) in brightness temperature scale, and response functions to temperature as a function of optical depth in plage (a) and in the cold pocket (c, e); Right panels: corresponding temperature profiles (solid lines, FoV average (dotted lines), and response functions to temperature at the core of the CO 3-2 R14 line in plage (b) and in the cold pockets (d, f). The observed and synthetic ALMA brightness is indicated.