Overview of a-type (–) HOCH₂CN transitions covered by the PILS spectrum towards the full-beam offset position of IRAS 16293B, illustrating the non-detection of these lines in this spectrum. The observed spectrum is plotted in black and synthetic spectra for a column density of 1.0 × 10¹⁵ cm⁻² and excitation temperatures of 150 (blue) and 300 K (red) are overplotted. The synthetic spectrum of the entire molecular inventory determined with PILS data towards this position is plotted in green. The quantum numbers of the transition are indicated at the top of each panel and the upper state energy is given in the top left of each panel.