Library management and other bibliographic database systems commonly assign local system control numbers to bibliographic records however these are primarily for internal database maintenance and of limited external value to users. Local system identifiers commonly change on migration from one system to another or with database management initiatives and they are therefore unreliable for long term identification purposes.


It is recommended that NBAs assign and maintain some form of unique bibliographic identifier for each record supplied to users in order that these can be managed effectively over time.