Fig. 10

Functional group standardization statistics. A total of 522,757 substances is modified in the Verify Functional Groups step, which normalizes non-standard functional group configurations to preferred ones based on a set of standardization rules, each of which is designated with an integer called a “transformation index” for convenience. The total number of substances modified in this step is smaller than the sum of functional group transformations because multiple changes can be performed in the same structure. Nine standardization rules set ionic bonds (8, 9, 10, 22-27), one sets complex bonds (15—the processing of transition metals), and two set dative bonds (11, 28). Rule 13 is not used, indicating that carbon monoxide is only encountered in the correct configuration