URLURI

URLuri is a term used in technical discussions to describe a string that can function as both a URL and a URI, or as a unified representation of a resource identifier suitable for use in both contexts. It is not an official standard, but a concept used to compare how URL semantics (location and retrieval) relate to URI semantics (identity) in web architectures.

Origin and usage: The concept arose to clarify the relationship between URLs (which identify resources by location and enable retrieval) and URIs (which identify resources without implying location). URLuri serves as a mnemonic device for designers to test whether a given identifier remains valid as a navigable web address while preserving generic naming and identification properties.

Structure and validation: A URLuri is typically a string that adheres to the URL syntax described in RFC 3986, including a scheme, authority, path, and optional query and fragment, and which is also acceptable as a URI by the same standards. Valid examples include https://example.org/resource. Non-examples include urn:isbn:0451450523, which is a URI but not a URL.

Applications and limitations: In design and documentation, URLuri helps discuss interoperability, routing, and resource discovery across systems that treat identifiers as interchangeable. It is not a formal standard; in practice, developers should reference URLs as URLs and URIs as URIs, recognizing that every URL is a URI but not every URI is a URL.

See also: URL, URI, IRI, URN, RFC 3986.