The IfcURIReference provides for identifying a Uniform Resource Identifier (URI). A URI can be classified as a locator or a name or both, that is it may comprise a Uniform Resource Locator (URL) and/or a Uniform Resource Name (URN).

• A Uniform Resource Locator, URL, is a string conforming to a standardized format, which refers to a resource on the internet (such as a document or an image) by its location.
• A Uniform Resource Name, URN, is intended to serve as persistent, location-independent resource identifier and is designed to make it easy to map other namespaces (that share the properties of URNs) into URN-space.

NOTE  See RFC 3986 for definition of Uniform Resource Identifier.

HISTORY  New defined datatype in IFC4.