I am currently trying to apply Patton's Symmetric Joe-Clayton Copula, described in his "Modelling Asymmetric Exchange Rate Dependence". I am currently looking for the closed-form relation (if there is any) between the upper/lower parameters of SJC and Kendall's tau. I've been looking into Joe's "BB7" family (Patton bases SJC on that), but I cannot find anything. Any help is appreciated! Thanks!