Total source function of Hε, effect of Balmer continuum line blanketing, and Hε multi-level source function for the FALC model. Upper panel: line (S_Hϵ), background (S_b), and total source function (S_t), for the FALC model including Balmer continuum line blanketing. The dotted grey line shows the ratio δ between line extinction and total extinction (Eq. (2)). The three vertical ticks mark the total optical depth heights τ_λ = 3, 1, 0.3. The 32% label shows that at the τ_λ = 1 height 32% of the total source function consists of the Hε source function. Middle panel: fraction of the total, line, and background source function including Balmer blanketing and no Balmer blanketing. The change in the total source function with Balmer blanketing results from a change in the Hε source function, only making up 32% of the total source function. Bottom panel: Hε source function split up in the multi-level source function terms (Eq. (14); scattering , thermal ϵB(T_e), and interlocking ηB(T_e)). The Hε source function is dominated by interlocking and not by the Balmer edge (dotted green), with the hydrogen ground level as the dominant intermediate level ().