ScalingStacks

Definition 7.1.3. We say that an open neighbourhood $U$ of $x\in X$ is small if it is homeomorphic to $\operatorname{St}\nolimits(n_{x})$, if $|\overline{U}-U|=n_{x}$ and if $n_{x^{\prime}}=2$ for all $x^{\prime}\in\overline{U}-\{x\}$.