IUPAC Chemical Identifier
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a proposal for a unique computerized label -
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The aim of the Chemical Identifier project is to establish a unique
label, the IUPAC Chemical Identifier (IChI), which would be a non-proprietary
identifier for chemical substances that could be used in printed and
electronic data sources thus enabling easier linking of diverse data
and information compilations.
IChI will not require the establishment of a registry system. Unlike
the CAS Registry System, it will not depend on the existence of a database
of unique substance records to establish the next number for any new
chemical substance being assigned an IChI. It will use a, yet to be
defined, set of IUPAC structure conventions, and rules for normalization
and canonicalization of the structure representation to establish the
unique label. It will thus enable an automatic conversion of a graphical
representation of a chemical substance into the unique IChI label which
can be performed anywhere in the world and which could be built into
desktop chemical structure drawing packages (such as ChemDraw, ISIS/Draw,
etc.) and online chemical structure drawing applets (such as ACD/Draw).
IUPAC would define the process flow leading from input structural information
to the creation of the Identifier in three steps: definition of chemical
structure input requirements, algorithms for generating a unique set
of atom labels (canonicalization), and algorithms for conversion of
these labels to the Identifier (serialization). Structure input and
conversion to the structural format required by the IChI generator would
be done by vendor developed software.
The process would be reversible, so that the Identifier output could
be used to recreate structural input information. The Identifier would
thus serve as the computer equivalent of the IUPAC name for a molecule.
This would facilitate searching the Internet and labeling information
in electronic documents with the name of the chemical substance in question.
A.
D. McNaught
7 February 2001
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