Isocontours of the ratio of the initial kinetic energy flux contained in an interstellar shock to the radiative energy flux contained in ultraviolet photons, , where 10⁻⁴ G₀ erg cm⁻² s⁻¹, as a functionof G₀, the shock speed V_S, and the pre-shock density n_H (indicatedon the isocontours). The dashed region corresponds to the parameter domain, for n_H = 10⁴ cm⁻³, where the amount of UV radiative energy reprocessed into heat within a shock is larger (on average) than the amount of mechanical energy reprocessed into heat (Eq. (36)).