On the net in its current design a number of publications change address (or even worse are simply removed).

As publication on the Internet becomes more widespread and starts to replace publication in the printed media, we expect that it will be possible to persuade copyright-holders who are interested in their publications remaining accessible to behave in the same way as copyright-holders of printed publications. Experience gained during editing the Danish Book List and administration of the Danish ISBN office has shown that Danish authors/publishers/publishing companies are very keen on their publications being registered centrally so they are accessible to users interested in lending or purchasing them, etc. This is revealed by the fact that they are so willing to submit publications voluntarily for registration. Informing the Danish ISBN office (which also maintains an updated base of publishing companies) of changes of address is also voluntary. But publishers and publishing companies always regard it as a natural step to take.

PURL server

Corresponding to registration in the ISBN system, and thus to updated address information in the publishing base, a PURL server has been established in connection with the Indoreg project at DBC (http://purl.dk). PURL stands for Persistent Uniform Resource Locator - i.e. a fixed URL. If this is to function properly, it is necessary to register with DBC in the same way as for printed publications, remembering to state any changes of address. The PURL server will then function as a central switchboard. The PURL is used in registration, and will be able to switch to the relevant address (and publication) at any time.

At the same time, registration with the PURL server has the same effect as submission of a publication for registration. On registration with the PURL server the publication owner also receives (in the same process) the offer of completing a metadata form, which can be used in subsequent national bibliographic registration as mentioned above.

Unambiguous identifiers similar to ISBN numbers for use as an international standard have been discussed regularly, but no solution has yet been found.

Automatic tools

As well as persuading publication owners to register publications in DBC´s PURL server and complete the metadata form, the use and development of automatic tools will also be necessary.

The following are needed:

Automatic check of the existence of addresses

Programs which visit the addresses registered and report significant changes in the length of publications

Programs which can compare clearly identifiable elements in our registration and the HTML coded publication on the net respectively.

Legal deposits

Guidelines for the current collaboration between the Royal Library and the Danish Library Centre concerning preparation of the national bibliography have been laid down in the National Bibliography Agreement. Among other things, this is based on the mutual exchange of publications (information about publications) to benefit legal deposits and the national bibliography. A similar form of collaboration is also planned for electronic publications, with legal deposit publications also being registered in the national bibliography at the same time as the publications registered in DBC´s PURL server are legally deposited (all achieved by using addresses).

Collaboration with other institutions

Collaboration with the Danish State Information Service, which maintains a database containing information about all state publications (including electronic publications) would be a good idea - not least because the Ministry of Research has issued guidelines entitled Netpublikationer : statens standard for elektronisk publicering. If these guidelines are observed, publications containing metadata will be produced. Close collaboration with various research institutions will also be necessary.

Maintenance of registration

The problem of when and to what extent registration should be changed because a publication has changed needs to be clarified. We also need to clarify whether (and if so to what extent) bibliographic registration should be compared with registered net publications to check whether registration is still valid.

A number of requirements concerning automatic checking of URL and length, as well as certain descriptive data, are mentioned above. It is worth adding the general comment that a "manual" check would reveal changes in eye-catching data such as title, copyright information, URL etc. fairly easily, whereas a more thorough investigation will be necessary if a change in contents is to be verified.

Our starting-point will be to check registration if we become aware of significant changes in a publication. And in this connection we hope that producers/suppliers will be particularly active in drawing our attention to any such changes.