Code word index

Different meanings are sometimes attached to the words indexing, classifying, and coding. 

Fig. 11.7. Random section of the COSMO frag database file five-digit atom word are separated by blanks. The first 8 words are the atom similarity codes of order 0 to 7, followed by 2 by-codes containing additional information. At the end of each line the molecule of each atom is marked, using a nine-letter unique name constructed from the molecule identity index, followed by information on the neighbor atoms and implicit hydrogens. In this section all atoms are identical up to the second order, while atoms 5 and 6 are the most identical (up to fifth order).

In other words, if si is the share of acquisitions that the firm makes in a sector corresponding to the SIC code x, then the Herfindal index is computed as the sum of the squares of the individual shares, Ssi2. This measure takes value one if all acquisitions are in a single sector, and becomes progressively smaller as a given number of acquisitions are spread over a larger number of sectors. 

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