Historic atom environment analysis. Most frequent atom environments as described by Adamson et al. . The term ‘incidence’ refers to the percentage of structures in the survey that contained a particular atom environment, ‘occurrence’ describes the fraction of all generated atom environments that were of the particular type. Incidence was used for ranking. Dashed line indicates aromatic bond. Adamson et al. did not provide a definition of aromaticity but distinguished between ring and chain bonds. ‘Ring’ and ‘Chain’ refers to the complete atom environment.