1. FORMULA -The molecular formula Figure shows the impact of the hash layers on whether or not two molecules are considered to be the same as well as the actual contents of the hash layers for two molecules. The first five layers are generated using the RDKit's implementation of the MolHash software from O'Boyle and Sayle . The layer containing the molecule's SGroup data (if present) is handled by canonicalizing the data and then converting it to a simple JSON representation. The inclusion of the ESCAPE layer (i.e., a free text field allowing arbitrary information to be incorporated into the registration hash) is inspired by the molecule key used as part of the Novartis small-molecule registration system .