Likelihood corner plots for the parameters in our combined PDR shock model. Internal panels give the two-dimensional likelihoods of PDR density, PDR UV field, shock velocity, and pre-shock density. Where shown, contours enclose the 95, 68, and 38% most likely regions of parameter space (they have been suppressed for the parameters of the coarsely sampled shock models). The green dot indicates the best-fit model shown in Fig. 3.