Classification Properties: The Information Significance of Hierarchical Levels

— The unified digital information space of knowledge is provided by the data of electronic catalogs of libraries and repositories, which are systematized according to information and bibliographic hierarchical classifications. Documents in this space are usually indexed, which makes them accessible to the most advanced methods of information analysis and search. The proposed approach is based on the laws of hierarchy and allows one to distinguish the systematized objects into general and particular based on the analysis of the distribution of the indices of the classification universe. The information significance of individual levels determined by these laws presupposes the existence of a boundary between general and particular in the structure of hierarchical classification, the identification of which is of applied importance both in classification theory and in librarianship. Based on the analysis of empirical data on the distribution of the indices of the classification universe of the Russian UDC standard, the possibility of dividing the systematized publications of the electronic catalog according to the breadth of coverage of the problems discussed in them into the areas of subject (particular) and fundamental (general) knowledge is shown. The empirically established boundary is determined by the hierarchical level of the distribution, at which the maximum of the accumulated indices of the main series is located. The use of the revealed regularity is possible for both assessing the quality of the classification and the electronic catalog, and when carrying out information searches by classification indices.