The first general definition of a molecular scaffold was the Murcko framework developed by Bemis and Murcko in 1996 . According to this concept, a scaffold consists of all the rings in a molecule and the non-cyclic chains connecting them, called linkers. Excluded from the scaffold are all terminal side chains. In addition to the Murcko framework definition representing molecular properties like atomic elements and bond multiplicities, Murcko introduced a more abstract representation that reduced each atom in the framework to a simple graph node and each bond to a simple graph vertex, called graph framework or archetype. The authors used their framework definitions to assess the structural diversity of a set of drug molecules.