Machine Readable Catalogue:

The past ten years have witnessed a great change in cataloguing practice with the increasing use of computers and network communications. Cataloguing standards have been rationalised to suit the changing cataloguing practices, which have been universally acknowledged and adopted. New physical forms of library catalogues have made their debut. The machine-readable catalogue is the most significant of these new forms of catalogue. 

In a machine-readable catalogue entries are rendered in a format which permits input and storage on magnetic tape or magnetic disc for manipulation in a computer. MARC format, UNIMARC, Common Communication Format (CCF) are standard formats. Access to the catalogue entries may be 'off-line' or 'on-line'. 'Off-line' means that the computer can be used only at certain times. At the available computer time, search must be made for a collection or batch of enquiries. On=line systems, however, are linked directly to the computers which can be used immediately or at any time for processing enquiries and searching. 

There are three major computer produced physical forms of library catalogues which are relevant to off-line access. These are: 

• Printed form: Entries are printed in a conventional book format and are available in multiple copies.  
• Card form: Each entry is transferred to one or more cards of standard catalogue card and are filed just as in a conventional card catalogue.
• Microform entries are transferred to microfilm or microfiche and are used with appropriate microform readers. 

In these forms, they are no more than the conventional catalogue forms, the only difference being their mode of production.