Information about Uniform Resource Name (URN) administration and workflow management for online dissertations

Registration and authorisation

If you have registered to report online dissertations to the German National Library, then you are also authorised to carry out URN procedures at the German National Library. Further information can be found at FAQs on archiving online dissertations at the German National Library.

You will receive a URN sub-namespace, beginning "urn:nbn:de" from the German National Library. For this, please contact the relevant contact persons at the German National Library using this e-mail address

In the following cases, authorisation data will be required:

Structure of URNs

General URN structure

Check digits

URNs are allocated decentralised and then reported to the German National Library. During this transfer process errors could occur (such as data entry errors or missing components) and these can be eliminated by the means of check digits. Before a URN is registered, the URN string is validated.

The check digit (P) is located immediately following the last element of the NISS. The Algorithm for check-digit calculation relates to the entire URN string.


An example:


At you can have the URN check digit calculated and then add it manually to your local system. A script can also be supplied on request.

URN character sets

The character set should be kept as simple as possible and should be limited to numbers, letters and certain special characters:

Only lower case characters are accepted. This limited character set helps to avoid software application conflicts.

Citing URNs

Two methods are available for citing online publications with URNs.

Presenting URNs

URNs are set out in accordance with formal rules of semantics and with regard to both their scalability and technical implementation they will be very adaptable in the future, although the system has not yet been universally adopted.


Presenting URLs

In conjunction with a domain address, a URL is a universally applicable reference point for a URN:


The "resolver address" points to the address of the namespace resolution system, administered by the resolution service authority.

Referencing a URN as a hyperlink

Character string


as a hyperlink points to the URL presentation of the URN:

The characters %3A are the encoding for the colon character which is not permitted in a URL (see RFC 1738).

Referecing a URN with no hyperlink (for example in print)

The URN follows its URL presentation in square brackets:



The reason for this duplicate presentation is so that the appropriate "resolver address" is brought to the user's notice. At the same time it ensures that if international circumstances change (e.g. international URN resolution), the URN will still be able to be used in its original syntactical form. Furthermore it is difficult for users to infer the original syntactical form of a URN in cases where only the URN is given.

Saving the URN in the resource

Persistent Identifiers for digital contents help on the one hand with the long term availability of online resources and on the other with a way of permanently citing them with certainty. As far as the ability of users permanently to cite URNs, the German National Library recommends inserting the URNs allocated in the project for digital dissertations into the resource itself.

It has been agreed with the "DissOnline" co-ordination agency at the German National Library that URNs can be formally positioned beneath the title, but before the start of the text itself.

In order that print and online dissertations are identical, this information must appear in both versions, i.e. URNs are to be integrated into resources by their authors themselves.

Bibliographic capture of URNs

Current capture of URNs and URLs in the PICA/ILTIS system at the German National Library

Capturing URNs and URLs in MAB records (available from 1 August 2004)

Transfer conditions and transfer interfaces for managing URNs at the German National Library

The German National Library can register URNs in various ways. The following options exist for online dissertations:

The particular features of the special procedure for initial URN registration of online disssertations are set out below. Full information on transfer arrangements and transfer interfaces for managing URNs at the German National Library can be found under the menu item "URN Implementation".

Initial URN registration of online dissertations using established procedures.

The workflow management for archiving online dissertations at the German National Library caters for registering both metadata and the object itself. Within the context of URN management, only reporting metadata to the German National Library is affected in the following.


Reporting and assigning URNs retrospectively at the German National Library

A special feature of URN management of online dissertations is the subsequent registration of a URN at the German National Library, even when the object has already been archived.

On request () the German National Library will supply a file, containing all the data records in a fixed format for which no URNs have so far been allocated. The URNs need to be added to these data records. The file is then returned to the German National Library. A comparison with the catalogue at the German National Library is carried out every six months, in order to reduce the workload.

A script which automatically generates URNs on OPUS operators' internal software sites is available to OPUS users .

Checking procedures

In order that only valid URLs are issued during the resolving process, a daily URL check is carried out. Additional consistency checks using hash codes are also available.
If URLs are identified as unreachable, then as part of the resloution process users will be automatically directed to the archive object identified by a URL at the German National Library.

URL error messages can occur temporarily, for example due to network connection errors or unstable servers. Once URLs are available again, the resolution process will point to them again. This procedure is fully automated. Identification of permanently inactive URLs, for example as a result of transfer to a new server, is currently handled by means of individual consultation.

Latest information can be found under the Statistics category..

Resolving URNs