The input to the EGAT architecture is an ordered set of features for each atom and bond in the reactant and product. Table and 2 list the input atom (i.e., node) features, n, and bond (i.e., edge) features, e, fed into the EGAT model, respectively, and their comparisons with input features of Chemprop. Many of the features could be incorporated as either distinct numeric values (i.e., integers) or categorical values (i.e., one-hot vectors). In such cases we elected to use integers over one-hot vectors wherever possible to simplify the representation. For example, hybridization in EGAT is represented using a four bit one-hot vector (i.e., this is clearly a categorical feature), but the number of bonded hydrogens are featurized with integers (i.e., this is a case that could be treated either numerically or categorically). Wherever one-hots are used, they are transposed and concatenated with the other features during the input preprocessing. The resulting dimensions for the featurized node and edge vectors are 17x1 and 14x1, respectively.