Limitations of Alphabetical index:

Readers must have some knowledge of the classification scheme used for the arrangement of entries before the person is able to consult the catalogue. While this is strength for logical grouping of subjects, it is at once a handicap for readers without anyidea of the classification scheme of the library. Alphabetical index has, therefore, to be provided to help a reader in the task of referringto the subject part of the catalogue as well as findings out materials of his interest from the library. 

a)  The absolute dependence of the classification scheme for the arrangement of the subject part of the catalogue restrains the autonomy of the cataloguer. 

b)  While new subjects can be introduced at the appropriate place in the classified part of the catalogue, it also poses difficulties for the users, if libraries place new subjects in two or more different places, as the classification scheme usually takes time to update and keep it current. 

Yet with all these deficiencies, the classified catalogue has found favour with many libraries, especially academic, research and special libraries, because most of the deficiencies may be overcome by a good alphabetical index and use of a good classification scheme. Given below are samples of main entry for a classified catalogue and for a dictionary catalogue.