IUPAC has just released the final version (1.02) of its InChI software, which generates Standard InChIs and Standard InChIKeys. (InChI is the IUPAC International Chemical Identifier.)
The Standard InChI “removes options for properties such as tautomerism and stereoconfiguration”, so that a molecule will always generate the same stable identifier – a unique InChI – which facilitates “interoperability/compatibility between large databases/web searching and information exchange”. Note also that any “shortcomings in Standard InChI may be addressed using non-Standard InChI (currently obtainable using InChI version 1.02beta)”.
On a practical level this means that the 27-character length InChIKeys (a hashed form of the InChI), with the following generic form
can now be readily and reliably generated and will start to be used in search indexing and linking applications.