Entries in a classified catalogue
In Ranaganathan's Classified Catalogue we find the following entries:
1) Main Entry
2) Cross Reference Entries
3) Class Index Entries
4) Book Index Entries
5) Cross Reference Index Entries
First two of the above are entries with call or class numbers in their leading section. The other entries are word entries with alphabetical words in the heading section. Ranganathan's Classified Catalogue, thus basically, consists of two parts. They are known as Classified Part comprising of Main and Cross Reference Entries and Alphabetical Part consisting of the alphabetical index entries, namely, Class Index, Book Index and Cross Reference Index Entries.
Of these entries, Main Entry, Cross Reference Entry and Class Index Entry are entries given under subjects. In other words, they are called subject entries. You may feel that in Classified Catalogue of Ranganathan there are many new terms and that you need some more clarity to understand the terms.