The IUPAC International Chemical Identifier (InChI), either in its standard form or one of the non-standard forms, provides a hash that could be used for molecular identity checking. InChI is also composed of a variety of layers, which can be carefully extracted and stored to provide some of the layers mentioned above. However, we opted not to use InChI in lwreg so that we have full control over both the molecular standardization and details of the hashing. Standardization is an integral part of the InChI algorithm and cannot be disabled .