Let $\mathfrak{X}$ be a strongly nondegenerate strictly polystable formal scheme with skeleton $\Delta$ and $\mathfrak{D}$ a subdivision of $\Delta$ with associated formal structure $\mathfrak{X}^{\prime\prime}$. Then there is a bijective correspondence between the open faces of $\mathfrak{D}$ and the strata of $\tilde{\mathfrak{X}}^{\prime\prime}$ given by

$$R=\red(p_{\mathfrak{X}^{\prime\prime}}^{-1}(\tau)),\hskip 56.9055pt\tau=p_{\mathfrak{X}^{\prime\prime}}(\red^{-1}(R)).$$

Furthermore, in the second equality, $R$ can be replaced by any nonempty subset of $R$.