OC|processor 18 comprises various modules that take the different modalities of chemistry into account, aiming at a comprehensive annotation of chemistry terms in documents. This allows the identification of novel concepts and compounds that were not yet known at the time before annotating a given document. If new compounds are identified, these are registered in Google BigQuery tables in the open access SciWalker-Open-Data project, giving access to >150 million small molecules with a unique standard InChI (version 1.03) . These unique InChIs were generated from connection tables generated from the SMILES representations of chemical structures. SMILES containing a wildcard entry (i.e. "*") were considered as representing a scaffold containing an undefined substituent and were not registered. Thus, the current approach is limited by the expressivity of SMILES as well as the InChI rules. For example, standard InChI will represent different tautomers of a molecule as one unique structure, while neither SMILES nor InChI consider coordinate (dative) or hydrogen bonds. Since valence isomerism is not handled by either system, this would result in different structures for molecules exhibiting valence isomerism .