Beilstein system fragments

The position of the entry for any compound is determined by that fragment of its structure which is classified latest in the Beilstein System. Thus, for example, a compound containing a heterocyclic ring, a carbocyclic ring and an aliphatic chain is classified as a heterocycle, irrespective of the other structural elements, since all heterocycles are ordered after acyclic and isocyclic compounds in the Beilstein System. This feature of the systematic classification of compounds is called the Principle of Latest Systematic Entry. 

The 12-digit Code. To illustrate this procedure, let us look at the example used above in Fig. 2 the structure is input, and the operation of the Beilstein System on the connection table is then carried out- The structure is recognised as being composed of three fragments (substructures), namely ... 

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