Fitted model to OCN⁻ absorption feature. Orange dashed and solid lines show red and blue OCN⁻ (sometimes attributed to CO absorption instead), showing that the bulk of the XCN feature is dominated by OCN⁻. The blue and purple lines show the Lorentzian and Gaussian contributions to the CO band, respectively. The XCN and CO bands are fit simultaneously. The total fit is shown in green. The 3σ uncertainty on optical depth is shown in shaded gray. The y-axis limit is set for better visibility of the ice features in all sources, which cuts off the fit to the CO band in B335. The fit to the CO ice band in B335 is similar to the other sources and does not overpredict the data.