checksum standard inchi inchi id IUPAC International Chemical Identifier (InChI) - a machine-readable character string describing a chemical structure, developed by IUPAC and the InChI Trust as a standard to allow interoperability and linking between chemical resources. The standard InChI differs from the non-standard InChI in that it is generated with a fixed set of parameters, ensuring consistency between different resources. The current version of the standard InChI software is 1.03. PSI-MI MI:2010 standard inchi structure representation attribute name