Beyond the Basics

ARK Anatomy



First part:

The first part of the link specifies the NMA, for “Name Mapping Authority” (, and the identifier scheme “ark:”. The addressing authority makes an ARK identifier “actionable” by allowing access to the object it identifies and/or its description.

The subdivision of the ARK into two parts makes it possible to present the same document in several dissemination contexts:

The hosting has changed, but the “ark:” section has not been modified. Thus, the same document can be identified in two separate locations.


Second part: 70795/x894tk

The second part of the ARK includes the name assignment authority (NAAN) as well as the identifier designating the object (the assigned ARK name).

The NAAN (Name Assigning Authority Number) specifies the organization that is authorized to assign the ARK in question. The NAAN of the National Library of Luxembourg is 70795. More than 500 organizations are found in the public NAAN register; among others, the National Archives of Luxembourg, the National Library of France, Princeton University and Google.

Behind the NAAN one sees the unique identifier (in our example: x8947k) that relates to a specific object in the collection. The strings identifying an object are generally “opaque” and do not communicate any information on the object to which they refer.

“In conversation” with an ARK

Given the arbitrary nature of the identifiers, there is the possibility to “inflect” an ARK. By adding the suffix “?info”, one can access the metadata linked to the resource and/or a declaration of permanence (a commitment by the organization detailing the dissemination period and the mode of distribution).

It should be emphasized that the creation of metadata associated with an object is not mandatory, but highly recommended in order to facilitate the use and management of ARKs.


Suffix Pass-through


Suffix Pass-through (SPT) is a feature that allows you to add any suffix to an identifier. The suffix is automatically added to the end of the identifier’s location URL (target). The global resolver (Name-to-Thing) introduced this functionality in order to reduce the maintenance burden by allowing a single identifier to stand in for many others.

Essentially, the SPT allows you to define each ARK as the root of its own “namespace”. Any user-added suffix (e.g. to form sub-object identifiers) will be passed through to the registered target object.

For example, the ARK (“the ancestor ARK “) provides access to the digital edition of a 1996 issue of the journal “Hémecht”. Using the suffix pass-through, all ARKs of the following sub-objects redirect the user to the components (in this case: articles and pages) of the initial ARK, without having these derivative URLs saved in the database: