Neon line-ratio diagnostic diagram, showing [Ne V]₁₄ / [Ne II]₁₂ versus [Ne III]₁₅ / [Ne II]₁₂ for the five regions analysed: full Ch 1A mosaic (red circle), nucleus (magenta diamond), circumnuclear region (violet hexagon), PAH ring (yellow cross), and PAH-deficient region (green star). Blue density contours indicate the pure AGN models of Feltre et al. (2016), while red contours show the AGN+shock models of Feltre et al. (2023). The red arrow illustrates the effect of adding a 0 − 90% shock contribution to Hβ to an AGN model with Z = 0.017, log(⟨U⟩) = −2.5, n_H = 103 cm⁻³, ξ_d = 0.3, and α = −1.7 (black cross; Feltre et al. 2016). Orange diamonds mark AGN+shock models with a 90% shock contribution, with shock velocities increasing from 100 to 400 km s⁻¹ (light to dark).