Scaffold Generator dissects fused ring systems, i.e. rings that share bonds or atoms, into their constituting separate rings. This is the case not only when returning scaffold building blocks but also for the generation of parent scaffolds (see below). Internally, the CDK Cycles.relevant cycle finder algorithm is employed for ring detection. This algorithm detects the logical union of all smallest sets of smallest rings (SSSR, also minimum cycle basis, MCB) in the given molecule . This way, fused ring systems are not detected as one entity, but their constituting cycles are detected separately. The Cycles.relevant cycle finder was chosen for Scaffold Generator to be in accordance with the original scaffold tree implementation . But in rare cases, this cycle detection algorithm identifies too many rings in a given molecule, defined as more rings than there are atoms in the structure. One example is the natural product (NP) CNP0103752, taken from the COCONUT database (Figure ). Since the overarching ring connecting all 11 glycosidic rings in the structure can be detected on many different paths, Cycles.relevant detects 2059 rings here. In cases like this, i.e. more rings are detected than there are atoms in the molecule, Scaffold Generator uses the algorithm Cycles.mcb instead, which identifies one single set of SSSR/MCB instead of the logical union of all possible ones . In CNP0103752, it detects a more useful number for this application of 12 cycles.