Specifically, what are InChI layers?
There are 6 InChI layer types, each representing a different class of structural information: • Main layer • Charge layer • Stereochemical layer • Isotopic layer • Fixed-H layer • Reconnected Layer Note: The Fixed-H layer is optional and can be selected by unchecking the ‘Mobile H Perception’ box in the InChI generation program. The Reconnected Layer is also optional and can be selected by checking the ‘Include Bonds to Metal’ box in the InChI generation program. While the InChI is divided up into different layers to describe different types of structural information, each of these layers is also split into sub-layers to allow full description of each part of the structure (note: there is no sub-sub-layering). For instance, the Main layer can be split up into three sub-layers: • Chemical formula • Atom connections • Hydrogen atoms You can see that the top of the above five structures has an InChI with all three sub-layers of the Main layer. The Main layer is also the only layer that wi
