Evolution of the solution with the number of lines considered for a benchmark run. Each row corresponds to a parameter, and each column represents a different number of lines from three to 13 ([C ii]+[O iii] 88 µm+[O i] 63 µm, +[N ii] 205 µm+[O i] 145 µm, +[Ne ii] 12.8 µm+[Ne iii] 15.6 µm+[N iii] 57 µm+[Ar ii] 7 µm, +[Ar iii] 9 µm+H₂ 17 µm+[Si ii] 34 µm+[Ne v] 14 µm. The horizontal black lines indicate the expected solution. The model used here is radiation-bounded.