Additionally, they preserve SMILES codes of their origin molecules, i.e. structures from the data set that possess the respective scaffold. These origins are subdivided into virtual and non-virtual ones. Non-virtual origin molecules are those that have the node scaffold as their original scaffold, e.g. their Murcko framework. Virtual origins on the other hand are molecules that generate the respective scaffold only through enumerative or Schuffenhauer dissection, i.e. it is one of their parent scaffolds. This concept has been introduced in Scaffold Generator based on the definition of virtual scaffolds described in the literature . This term denotes scaffolds that are not directly in the data set but only identified when parent scaffolds are generated. If a scaffold node has only virtual origins, it is a virtual scaffold in Scaffold Generator. When analysing the results of a high-throughput screening (HTS) campaign, virtual scaffolds can be of particular interest if many of their child scaffolds exhibit bioactivity. A promising next step can be a second screening with a smaller library based on this scaffold because the first screen might have failed to include the true active scaffold structure.