Chemprop supports the input of atom-mapped reactions, i.e. pairs of reactants and products SMILES connected via the "> >" symbol by using the keyword --reaction. The pair of reactants and products is transformed into a single pseudomolecule, namely the condensed graph of reaction (CGR), and then passed to a regular D-MPNN block. The construction of a CGR within Chemprop is described in detail in Ref. 59, and summarized in the following.