With these potential variations in mind, it is worth considering whether if one were to design from scratch a linear notation for molecules for use in Deep Neural Networks, that syntax would be SMILES, DeepSMILES, or indeed a variant of one of the other chemical line notations. What are the features of these strings that aid learning the underlying chemical structure, and what are those that hinder? Perhaps the perfect notation would be one where (1) every string represents a valid molecular structure, (2) there are few duplicate representations, (3) small changes in the string tend to result in small changes to the structure (and vice versa) and (4) string size is related to pharmaceutical usefulness or synthetic accessibility.