All Library materials are arranged according to the Library of Congress Classification schedule (as shown below) which divides the knowledge field into 21 classes.  Each of these subject fields is denoted by alpha-numerical notation (e.g. BC 246) and the first three alphabets of the author in place of the cutter numbers.  The class mark and the first three alphabets are known as the call mark.  The call mark is printed on the spine, while that of the Journal is written boldly on the front cover of the Journal.  This call mark is also shown on all the data entries made on the Library’s OPAC or the Manual Catalogue. 

Therefore for example the title: Medical Education in Nigeria by Mu’uta Ibrahim will have the following call mark on the spine or in case of a journal written boldly on the front cover of the journal e.g. R824.N6.

The class number indicates the subject of the book, while the author cutter number helps to arrange books with the same class number in alphabetical order under the surname of their authors.