root namespace

From is designated as the root namespace for several metadata specifications, both public and specific to individual organizations. Even though not essential for URI schemes as such, associating an URI with a real, machine-accessible resource enables computer programs to follow directions given by the resource, e.g. validation rules, or references to further resources.


Currently, has two kinds of namespace service in place:

XML schema access from URI

URIs under the /schemas path point to metadata definitions specified in the XML schema language. As an example, will retrieve the first draft of an XML schema based on EN 15907.

Declaring an XML namespace with one of these namespaces offers the advantage that any corresponding XML document (such as a filmographic metadata record) can be checked for syntactic validity using any validating XML parser that has access to the net via HTTP.

Resolvable URIs for SPARQL

URIs under paths /localdefs and /pubdefs point to definitions of individual metadata elements expressed in RDF/XML. The /localdefs path is provided for in-house definitions, while anything under /pubdefs is from community specifications or public standards.

These definitions can be used in many ways. A very basic usage is obtaining a natural language definition (if present) of the element, e.g. . A more interesting feature of these URIs is that they can be referenced in SPARQL queries. This means that a definition can become a part of a reasoning chain, e.g. for checking the validity of a metadata statement not only syntactically, but also with respect to semantic assumptions.


What is a namespace?

A namespace puts a statement (or a whole collection of statements) into a given context. For example, a title statement can have quite distinct meanings in law, art, librarianship or filmography. Associating title with a namespace from the law community will prevent confusion with notions of title from other communities.

Do namespaces need to be registered?

They need to be globally unique. Any method to ensure uniqueness is OK. If your institution has a name in the Internet Domain Name System (DNS), then this is guaranteed to be unique throughout the internet and can be safely used for constructing Uniform Resource Identifiers (URIs). If you prefer other URI schemes such as Uniform Resource Names (URNs)[1], then you will have to register your namespace with one of the identifier registries and possibly also with an identifier resolution service.

URIs don't have to be valid network addresses, or do they?

This depends on what we expect. If the only purpose is to have a unique identifier, then you can construct any naming scheme based on an internet domain name. If you want to associate your identifiers with any kind of further information (e.g. in order to become part of a linked data infrastructure), then you should take measures for your identifiers to behave as valid URLs[2].

What if my institution loses its domain name?

This is a real risk. If your institution fails to pay the bill from the domain registrar, then your domain name may indeed be gone. In some cases you may be able to buy it back (often for significant money) from a so-called domain grabber. If it is gone forever, then the identifiers constructed under the domain name do not necessarily become invalid. However, you will lose the ability to connect them with your data.

Can guarantee persistence of identifiers?

At present, the domain is hosted by the Deutsches Filminstitut - DIF. This guarantees stability for the foreseeable future. Should an unforeseeable event make a change in the hosting institution necessary, the operation of would be relocated to a new safe place selected by its user community.

If I use as the root namespace, how can identifiers be attributed to my institution?

Let's say the acronym of your institution is ABCD and you are located in the Marshall Islands. Then your in-house identifiers would be prefixed with /localdefs/mi/abcd.

Will there be any cost for submitting schemas or identifiers?

No. We may, however, reject an XML schema or an URI scheme if it is out of scope for the film archive community.

Will operate a URN resolver service?

No. In special cases, we may configure redirection of specific HTTP requests to other servers, e.g. if there is a huge database behind an ID scheme.