In terms of functional groups attached directly to reacting aromatic rings the analysis covers more than 50 substituents that range from the four halogens to more exotic functionalities such as propellanes, imines, azides, and trifluoroborates. A subset of these groups is provided in Figure . An overview of functionalities present elsewhere in the dataset is provided in the SI (Figure ). These include common amine protective groups like tert-butyl oxo-carbonyl (Boc), benzyl oxo-carbonyl (CBz) and tosyl/nosyl sulfonamides as well as synthetically useful functional groups like silyl ethers, amides, esters and lactones, succinate esters (HOSU-esters), alkynes and olefins, aldehydes, ketones, and ketals. The set also covers conjugated epoxides and acrylonitriles, Weinreb amides, enol ethers, primary alkyl and benzyl halides, phosphonates, and unprotected catechols. Indeed, the dataset was assembled to cover not only a diverse set of ring systems but also a wide range of typical as well as less common functional groups to demonstrate the usefulness of RegioSQM as a synthesis planing tool.