The chemical operator changes only one atom (Figure ) or bond (Figure ) to ensure the explanation is defined for exactly one atom or bond. The molecules are represented as molecular graphs with implicit hydrogens, considering chemical validity is sufficient to determine the location and number of hydrogens. The decision trees of chemical operations shown in Figures and ensure the application of only one chemical operation per atom or bond. For atoms, the decision tree (Figure ) is as follows: if the atom is a heteroatom (noncarbon), then convert this atom into a carbon atom; else remove the carbon atom if it is a terminal atom (methyl group). For non-terminal carbon atoms, there is no chemical operation to avoid breaking the molecule into several molecules. For bonds, the decision tree (Figure ) is as follows: if the bond is unsaturated, then saturate this bond; else break the bond if the bond is in a ring. For saturated bonds not in rings, there is no chemical operation to avoid breaking the molecule into several molecules. The decision trees define pairs of molecules that are directional since the chemical operations have a direction. The paired molecule might not be found in the existing dataset. For larger datasets, the odds of finding the paired molecule are higher. The different decision trees of chemical operations are the main differences between the approaches for atomwise and bondwise attributions. The explanation values for different atoms (or bonds) in one molecule can be identical, as visible in Figures and, when the paired molecules are identical, for example, for neighboring methyl groups.