www

WWW Names and Addresses, URIs, URLs, URNs

You should be able to reach anything I have on UR* from this page directly or indirectly. - TimBL

Specifications

URI (RFC 1630)

Universal Resource Identifiers (URIs) is the name for a generic WWW identifier. The URI specification simply defines the syntax for encoding arbitrary naming or addressing schemes, and has a list of such schemes. See: The specification of URIs as used by WWW is to be distributed with informational status in the Internet community. It is also published as RFC 1630.

URLs

The specification of URLs defines the encoding for specific access protocols, as defined by the URI WG and edited by various people This specification is not stable yet and does not necessarily describe WWW practice. Not part of the specification, now historical: WWW will use any new forms of naming which give features such as persistence and redundancy, when the are available, by extension of the set of schemes in the URI.

Other published notes:

URN

So far there is:

Mailing lists

This subject is discussed by the URI working group of the IETF (mail uri-request@bunyip.com to join). The following material may also be of interest:

General Background Material

UR Terms

This is my personal view and explanation.
URI
Universal Resource Idenifier. The generic set of all names/addresses which are short strings which refer to objects. (Originally UDI in some www documents) See URI spec ..
URL
Uniform Resource Locators. Term introducted by the IETF in forming the URI working group to point out that currently available URIs are mainly addresses rather than names. Exactly what consitutes a locator as opposed to a name is basically lack of persistence, but this is a much discussed point and impossible to define precisely. In practice, the set of schmes referring to existing protocolls, listed in the URL specification .
URN
Uniform Resource Name. 1. Any URI which is not a URL. 2. A particular scheme which is currently (1991,2,3,4) under development by the IETF, which should provide for the resolution using internet protocols of names which have a greater persistence than that currently assiated with internet host names or organizations. When defined, a URN(1) will be an example of a URN(1).
	 _______________________________________________________
	|							|
	|	 _______________	 _______________	|
	|	|  ftp:		|	|  urn:		|	|
	|	|  gopher:	|	|  fpi: ?	|	|
	|	|  http:	|	|		|	|

	|	|  etc		|	|		|	|
	|	|_______________|	|_______________|	|
	|		URLs			URNs		|
	|_______________________________________________________|
				   URIs
URC
Uniform Resource Citation. A set of attribute/value pairs describing an object. Some of the values may be URIs of various kinds. Others may include, for example, athorship, publisher, datatype, date, copyright status and shoe size. Not normally discussed as a short string, but a set of fields and values with some defined free formatting.
W3C
webmaster@w3.org, November 1994