While HierS overcomes most limitations of the Murcko framework approach and is a good first attempt for scaffold classification, it also has some disadvantages: ring systems are not split into their constituting single rings, which can be especially problematic when studying complex ring systems of NP where the approach may be too coarse-grained. In addition, child scaffolds are linked to multiple parents in the hierarchy, which is a multi-class assignment that is often undesirable for classification tasks.