Records in the automated cataloguing systems are identified by internal record numbers. Publishers that request an ISSN or an ISBN for a document should deposit one or more copies of the document at the deposit library as soon as it is published. In countries with voluntary deposit, new ISSNs and ISBNs are collected by the deposit acquisition service and matched with deposited publications. In this way publications that have not been deposited are detected and ordered. Newly deposited publications may be registered by their identification number.
Identifiers are a part of the bibliographic description.
Identifiers are indexed for retrieval purposes and are one way to locate publications in OPACs and to order them for inter library loan purposes. As we can see, the different parties involved in handling electronic documents will have different requirements for identifiers that will meet their demands. The idea of defining one identification scheme to meet all these needs is unrealistic. The use of identifiers is very much incorporated into the publishers business methods and it might be difficult, if not impossible, for the national libraries to impose one standard on all publishers simply because this would be convenient for the national libraries. Specific publisher related requirements, e.g. the need to identify every right owner in a document or to track pieces of content through the production process, are not a part of the requirements.