The overriding principle behind cataloguing library books is to be able to describe them in such a way that each book is unique and can be easily identified on the library shelves. This identity is further enhanced by the call-mark assigned to a particular book during the classification process by cataloguers. This operation is one of the highly technical professional duties in the library world. Libraries, therefore place much premium on their cataloguing sections and in some libraries professional librarians who are cataloguers are better remunerated than their colleagues working in other sections.