Interlocking source function description of the Ly-β spectral line synthesized from the FALC atmosphere. Panel (a) shows the contribution to interlocking by the different intermediate states, expressed by 38 and paths, expressed by 41. γ₂, γ₄, and γ₅ refers to the intermediate states n = 2, n = 4, and continuum, respectively. ω₁ refers to the first-order path connected to p₂₁(1 − p₅₄p₄₅) and p₂₃(1 − p₅₄p₄₅). Panel (b) explains the dominance of the first-order path ω₁, with P_ij the transition rates and p_ij transition probabilities between states. Panel (c) shows the contribution of the source function connected to ω₁ (blue) to the “total” interlocking source function.