Tracing is a separate paragraph. This is the last paragraph in the Main Entry of a Dictionary Catalogue., This part traces the additional entries that are provided for the document. Added entries may be needed for a book for all the four approaches author, title, subject and series. Since in a dictionary catalogue main entry itself is an author entry except in the case of the Title Main Entry, the author entries indicated in the tracing are entries for collaborators like joint authors, editors, compilers, translators, illustrators, commentators, etc.
A Tracing paragraph is broadly divided as consisting of two parts with different number sequence. In the first unit, subject headings are given in Arabic Numerals. Remember a subject heading may be a single word or word group or it may have a sub-heading also. In the second part collaborators, title or titles and the series are given in a-sequence numbered in Roman numerals. In this sequence series is always the last item. If there is no series then title is the last item. The nature of the document catalogued 'decides the subject headings to be given and the other added entries needed including title added entries and series added entries. If you compare the illustrations given earlier in this Unit, you can understand how different documents give scope for different number of added entries, and also the way in which tracings are recorded as a paragraph in the tracing section.
Opinions again differ regarding the need for the tracing section in a catalogue entry. Tracing section actually is useful to the staff in the library, who will prepare the relevant added entries from the main entry. The user, as such, is not benefited much by looking at the tracing section. Some people therefore, say that the tracing section can conveniently be given up. But while preparing a catalogue slip or when the unit record system is observed for entries in the print form or the near print form then tracing section is helpful for the library, if not for the user.
Ranganathan feels that tracing section is mainly for the library staff. At the time of preparing additional entries or at the time of weeding out of books from the stock the tracing section will help in updating and rectifying the catalogue.
Even in a dictionary catalogue, if a book is weeded out of the library stock or if it is lost and not replaced then the relevant entries for that book in the catalogue should be deleted. Tracing section helps in such situations.
In the Classified Catalogue Code Ranganathan suggests that the tracing section should be given only on the reverse of the catalogue entry of Main Entry Card. The tracing section cannot be immediately seen by the user.