Abundance of H₂CCCHC₃N both in the gas (solid lines) and in the mantle (dashed lines). Blue lines correspond to the model in which H₂CCCHC₃N was formed both in the gas and on grains, while red lines show results from the model in which cyanoacetyleneallene was produced only on grains. The range of column densities derived from Source Models A and B are represented by the horizontal gray bar.