A combination of scaffold dissection and single-parent assignments through chemical prioritisation rules is the scaffold tree approach by Schuffenhauer et al. . As a first step, scaffolds are extracted from the given molecules according to the Murcko framework definition but additionally including all atoms connected via a double-bond to ring or linker atoms in the scaffolds. These elements are included as well to preserve correct hybridisation and structural alignment of the scaffold atoms. Via an iterative removal of rings, smaller parent scaffolds are created from the original child scaffolds. Ring perception for the removal is based on a smallest set of smallest rings (SSSR) approach. This way, ring systems sharing atoms or bonds between multiple rings are not considered as one entity but dissected into their constituting rings as well. One important aspect about the scaffold tree approach is the application of 13 chemical prioritisation rules at every ring removal step. Following these rules, only one terminal ring is specifically selected for removal and only one possible parent scaffold created at every scaffold dissection step. The term "terminal" indicates that the removal does not result in a disconnected scaffold structure. The specific prioritisation rules take only molecular characteristics of the rings, like size, hetero atom count, and aromaticity, into account and aim at removing the less characteristic, peripheral rings first to extract the characteristic, central parent scaffold. The scaffold dissection process continues until only one ring remains. When studying a collection of molecules, their original scaffolds and sets of created parent scaffolds are arranged in a hierarchy tree, the scaffold tree. Single-ring scaffolds form the roots and more complex scaffolds are placed at the higher levels. Due to the linear scaffold dissection process using the prioritisation rules, every child scaffold in the hierarchy is exclusively assigned to only one parent scaffold. Therefore, the scaffold tree represents a hierarchical, deterministic, and unique classification of chemical scaffolds. Unlike SCONP, it is datasetindependent because it does not consider the frequency of a scaffold in the studied collection.