Chemical structure, representation Wiswesser line notation

Eakin [13] describes the chemical structure information system at Imperial Chemical Industries Ltd., where registration is based on Wiswesser Line Notation. For connection tables, the unique, unambiguous representation is derived automatically, i.e., a single, invariant numbering of the connection table is algorithmically derived. 

These identifiers were developed as an lUPAC project in 2000-2004. They are the most recent technology aimed at an unambiguous text-string representation of chemical structures. (Earlier technologies included Wiswesser line notation, which is not described here, and SMILES, described below.)... 

The efforts in computer technology were based on non-graphic business applications, so it was most practical for the chemical information systems to be made to adapt to the standard business computer. Systems evolved that were based on linear representations of graphical formulas, such as Wiswesser Line Notation, WLN (see Figure 3), or standard chemical nomenclature. But the linear representations were one step further removed from the 2-D structure that the chemist so depended on, and involved learning what in essence was a foreign language. The chemists found themselves more and more alienated from their own literature, and information intermediaries found their place in the sun. 

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