Zoom-ins of the CX Tau spectrum (black) around the [Ne II] and [Ne III] lines. In the left panel, a Gaussian fit to the [Ne II] line is shown in dark blue together with the best-fit H₂O model from the 13.5-17.5 µm range in light blue. In the right panel, the combined model containing ¹²CO₂,¹³CO₂, HCN, C₂H₂, H₂O, and OH is shown in red. A blue dashed line indicates the position of the [Ne III] line and the shaded region surrounding it indicates the region in which the upper limit on its flux is derived.