APEX-detected spectral lines of HCN and HNC isotopologues towards R CrA IRS 7B (black histogram), with corresponding LTEMCMC models shown as solid red lines. The HCN and HNC J = 3–2 transitions, exhibiting excitation temperatures (T_exc) of 26(5) K and 27(5) K, respectively, and a column density ratio N(HNC)/N(HCN) ≈ 0.30. The H¹³CN and HN¹³C J = 3–2 transitions, with T_exc of 11(3) K and 12(2) K, respectively, and N(HN¹³C)/N(H¹³CN) ≈ 0.38. The HC¹⁵N and H¹⁵NC J = 3–2 transitions, with T_exc of 11(4) K and 14(2) K, respectively, and N(HN¹⁵C)/N(HC¹⁵N) ≈ 0.39.