This part of ISO 8459 specifies and describes data elements required in the interchange of data between cataloguing systems (i.e. terminal to computer or computer to computer). It also identifies messages and their data elements which are used in cataloguing systems. It is intended to support both batch and interactive cataloguing transactions. Annex B provides examples of how this part of ISO 8459 may be used. The structuring of the data elements into messages falls outside the scope of this part of ISO 8459.