The InChI Key is a fixed-length (27-character) condensed digital representation of an InChI, developed to make it easy to perform web searches for chemical structures. The first block of 14 characters for an InChI key encodes the core molecular constitution, as described by a formula, connectivity, hydrogen positions, and charge sublayers of the InChI main layer . The other structural features complementing the core data, namely exact positions of mobile hydrogens, stereochemical, isotopic, and metal ligands, whichever are applicable, are encoded by the second block of InChI Key. (The InChI Key is described in detail here () . Figure show an example of InChl and InChl Key representation of organic compound .