A model function²² 2 Model functions are called algebraic in [CL06] and smooth in [CL10]. is a function $\varphi$ on $X$ such that there exists a model $\mathcal{X}$ and a divisor $D\in\Div_{0}(\mathcal{X})_{\mathbf{Q}}$ with $\varphi=\varphi_{D}$. We let $\mathcal{D}(X)=\mathcal{D}(X)_{\mathbf{Q}}$ be the space of model functions on $X$.