A scheme of classification is but a tool in the hands of the library to organise subjects and to serve them out in an efficient way. Therefore, it is necessary that a lot (sire and thinking should go while choosing a classification scheme for a library. Classifications schemes are of different types. Broadly speaking, there are two types, namely, Enumerative and Faceted schemes. While Dewey Decimal Classification and Rider's International Classification be-long to the former type, Universal Decimal Classification and Colon Classification may be considered as Faceted schemes. For details regarding these schemes, you may consult Block 4, Units 10-12 of Course III. Each classification scheme has its own merits and demerits. This makes the choice a little bit difficult. It is easily said that the scheme which satisfies the needs of the library and its clientele should be chosen. Ranganathan has suggested the following points for consideration:
He suggests the use of four scores: 0 Poor; 1 Passable; 2 Fair; and 3 Good in the scheme. Perhaps, this method would be very good for the choice of a scheme of classification, especially in special libraries.