Figure 1.

A molecule depicted by different scaffold representations. The molecule (a) is dissected into (b) Ring Systems: cycles within the graph representation of the molecules, (c) Linkers: atoms that are on the direct path connecting two ring systems, (d) Side Chains: any non-ring, non-linker atoms, and (e) Murcko Framework: the union of ring systems and linkers in a molecule; (f) Graph Framework can be obtained by considering all atoms and bonds in the molecule indentified as carbon and single bond. Different complexity-level ring systems include (g) Ring Assemblies: contiguous ring systems, (h) Bridge Assemblies: contiguous ring systems that share two or more bonds, and (i) Rings: individual rings; (j) The different levels of the Scaffold Tree.