CATALOGUING AND CLASSIFICATION 

Cataloguing and classification are two interrelated processes that are performed in a library. The basic purpose of these two operations is to aid the readers (users) of the library in locating and selecting appropriate library materials (documents as well as others) required for their study and research, in case such materials- are present in the library. To a large extent, these two processes are complementary and supplementary to each other. 

Classification decides the subject of the book and hence books are arranged according to class numbers on the shelves of the library. As books are physical entities these can be placed only at one location on the shelves of the library. When books deal with only one subject (e.g., An Introduction. to Mathematics) then this scheme is useful to the readers. 

But when a book/document deals with two or more main subjects or subdivisions of a main subject, we cannot keep the book (physical entity) at two places/locations on the library shelves. Ideally this book should be kept at two places, one at cataloguing and another at classification in order to reveal the subject of the book. But this is not possible. This book can be kept at only one place i.e. Library Cataloguing. The second subject library classification is brought to the notice of the reader by preparing analytical entry under the class number for classification. Such analytical entries prepared for all books dealing with two or more subjects or for multidisciplinary subject or subjects representing phase relations. Thus, cataloguing supplements - classification. Similar is the case for books of anthologies and readings where contributions are made by various authors. In these situations, author analytical entries are prepared in order to bring to the notice of readers the authors of different contributions. Thus, we find that cataloguing and classification are supplementary and complementary to each other. Both these activities jointly bring to the notice of the readers the whole contents of the documents possessed by the Library. Consult the sections on Analytical Entries from the Block 3 of BLIS-4P and Block 4 Subject Indexing of this Course, for further explanation of the interrelationship between cataloguing and classification. 

A library catalogue can also be used as a reference tool for answering many questions of users of documents. In fact, the library catalogue is used on most occasions as the starting tool for answering enquiries related to information on documents. 

For example readers 'queries on books written by a particular author, books on a subject or full name and year of birth of an author, real name of a pseudonym or a full name of an Institution, etc. can he answered with the help of a library catalogue. 

A library catalogue usually contains other valuable information on documents, besides bibliographical data for accessing and locating documents. The Notes Section, Collation (which includes illustrations and related data), etc., provide useful starting points for a search for documents on subjects.