Why are layers used in an InChI?
Taken from the InChI Technical Manual. “Since a given compound may be represented at different levels of detail, in order to create a robust expression of chemical identity it was decided to create a hierarchical ‘layered’ form of the Identifier, where each layer holds a distinct and separable class of structural information, with the layers ordered to provide successive structural refinement.” Layers are used because they are logical (they separate the variables) and understandable; they are flexible for chemists (they represent known levels of information) and extra layers could easily be added to future releases of the identifier (e.g. conformations, coordination etc).
