Can an InChI be invalid?
If an Identifier is produced, it will be a unique representation of whatever was submitted and is not ‘invalid’. While some checking is done, and warnings are issued if the input structure is ambiguous, errors and ambiguities in the input will remain in the output. If, for example, a molecule with hypervalent C is submitted (e.g. ‘C(CH3)6’), a valid InChI will be produced, though with a warning that the carbon valence has been exceeded. InChI should not be used to represent mixtures (except in the special case of a racemic mixture).
