Therefore, RXNMapper was utilized to map the remaining reactions. If some species are completely unmapped (due to multiple candidate species present after step 6), they are removed from the relevant reactions, which are then processed by steps 6 and 7 again. In some cases such as Figure , due to complex species, the balanced reaction SMILES string length passed in exceeded the maximum sequence length that the mapper could cope with, resulting in errors. These reactions are removed, together with any imbalanced reactions that could not be balanced with help species in step 6. The final set of 64,499 reactions are fully balanced and mapped, ensuring every product atom can be traced back to a reactant atom.