Vertical plane passing through the field line containing the feature. The field line is shown by the dotted black line. A vertical plane with a curved base, containing the field line is shown for various quantities. The base of this plane on the τ₅₀₀ = 1 surface is indicated by the dashed green curve in Fig. 9. Panel (a) shows the proxy (normalised κ) in the vertical plane. Panel (b) is the hydrogen number density at the n = 2 atomic level. Panels (c) and (d) are the vertical velocity and magnetic field components. Panel (e) is the temperature. Panel (f) shows the viscous and resistive heating rate. A time-series for the evolution of this feature and its MHD properties and heating in this plane is available online.