The main objective of any computerised cataloguing system is to create appropriate catalogues for different categories of libraries.
The key functions of any cataloguing module are:
The data entry for the creation of records for the collection of documents acquired ,for the library is very important. It is customary for library systems to use the same bibliographic record for ordering and acquisitions function as is used in the cataloguing. The cataloguing systems designed for any library must be in a position to handle the MARC record format. The use of MARC format facilitates use of externally created bibliographic records for producing the catalogue for the library. This is because many cataloguing systems are totally MARC based while many others can accept records in MARC format and can convert them into their own internal format. Most of the cataloguing systems have provision to automatically update index files as soon as a new record is added to the file.
Downloading capability facilitates the system to download relevant entries from some bibliographic utilities into the catalogue of the library without duplicating the effort of cataloguing.
Authority control file is very important where the form of index terms or headings such as author headings and subject index terms need to be controlled and standardized. Consistency is one of the important factors to he considered when the terms for headings are selected. To facilitate this objective libraries maintain authority files. These files are usually constituted either while cataloguing or indexing of the documents acquired for the library. This operation is generally accomplished by verifying the authority file through display and then adding the new headings immediately to the authority file many cases the subject authority file may take the form of a thesaurus that displays the full range of related, narrow and broad terms in use. Standard tools such as AACR-2, Dewey Decimal Classification and the ISBDs (International Standard Bibliographic Descriptions) have contributed to a great extent to the standarisation of catalogue records. AACR-2 and ISBDs are very widely accepted and adopted for the preparation of standard catalogue records.