0$ or ${\varphi}(f) \in \{ a_0^{\pm 0}, b_0^{\pm 0}, \dots, b_{n_0-0}^{\pm 0} \}$ if $i =0$ and $f, f^{- 0} \in {\partial}{\Delta}$, or $\Gamma$ consists of all faces of an equivalence class $[\Pi]_{\sim_