A number of records are created in a library for its collections to serve different purposes. Some of these records are accession register, shelf list, periodical holdings register, etc.
An accession register of a library is a date wise record of reading and reference materials acquired by a library either by purchase, exchange or through gift. Details of information pertaining \to the date of acquisition, the serial number of the item, i.e., the accession number, author, title, edition, publisher, date of publication, price, mode of acquisition, supplier, etc. are recorded in the accession register. It serves as an authentic inventory of items acquired by the library. As it is a date-wise record of the collections and arranged according to the serial number of the items, it cannot serve as a finding tool for documents available in the library from the point of view of author, title or subject. To locate or find out a particular item, the entire accession register has to be searched serially, which is a very time consuming operation. One needs to know the accession number of an item to search in the accession register. The accession register is used to find out every bit of information on an item, which is not available in any other record. It is also a permanent record of the library and fulfils the function of a stock register.
An accession register is distinct from a library catalogue. Although it also carries all bibliographical data of documents, yet it cannot serve the functions of a library catalogue.
The shelf list is an inventory record of a library which records bibliographical data of items arranged exactly the way the items are arranged on the shelves of a library in various rooms, halls or floors. Each item is represented by a card. giving call number, author's name, title, edition, volume number, copy number, accession number and such other details as deemed necessary for a particular library. The call number represents the class number, the book number and the location symbol. The reader can easily obtain the needed book from the shelf by this number. However, this order of arrangement just reflects the order of arrangement of items on the shelves. A shelf list, thus, primarily, serves as an inventory and controls the movement of the collection. It is the most important tool for checking the stock of a library. A shelf list resembles a library catalogue in many ways. It may also serve as a classified catalogue when such a catalogue does not exist in a library. But its function is different from that of a library catalogue. It does not provide approaches by author, title or subject.
The periodicals holdings register which gives detailed information of the volumes of journal titles available in bound or unbound form, is another useful finding tool in a library. Quite often the information in this register is transferred to the library catalogue. But a separate register is also maintained. This register cannot serve as a library catalogue as it is confined to periodicals only. Thus, a library catalogue is an unique and distinct tool to fulfil some of the most important functions in using a collection of a library. It helps to locate a document even if it is demanded either by author, or title or subject of the book.