urn: URLs
A Uniform Resource Name (URN) is a URI that identifies a resource by name in a particular namespace. URNs provide globally-unique names for resources as opposed to providing information about their location (URL).
Syntax
An URN minimally consists of a Namespace Identifier (NID) and a Namespace Specific String (NSS):
urn:<NID>:<NSS>
Components
<NID>- : A NID (Namespace Identifier) is a case insensitive identifier for the namespace (e.g.,
ISBNandisbnare equivalent). NIDs are maintained by registries such as IANA, and their resolution depends on the specific namespace. For instance, theISBNNID resolution is handled by International ISBN Agency systems.
- : A NID (Namespace Identifier) is a case insensitive identifier for the namespace (e.g.,
<NSS>- : The NSS (Namespace Specific String) is a string unique within a URN namespace. The combination of the NID (unique across the entire “urn” scheme) and the NSS ensures that the resulting URN is globally unique.
Examples
ISBN URN
This ISBN corresponds to the book Nineteen Eighty-Four by George Orwell:
urn:isbn:9780141036144
IETF URN
This URN corresponds to the IETF specification {{rfc("7230", "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing")}} :
urn:ietf:rfc:7230
Specifications
{{specifications}}