L2 setting of AFGL 2136 in the range where absorption lines are present. In red is shown an LTE model of HCN at column density and temperature of 1 × 10¹⁷ cm−2 and 500 K respectively, and C₂H2 at column density of 8 × 10¹⁶ cm−2 and 500 K respectively. The identifications of the HCN v₁ band and C₂H2 v₂ + (v₄ + v₅) band are given as blue and green dashes respectively. The grey model is the atmospheric ATRAN model and regions of very bad transmission have been masked out of the science spectrum.