Uniform Resource Names (URNs)
RFC 8141
Internet Engineering Task Force (IETF) P. Saint-Andre
Request for Comments: 8141 Filament
Obsoletes: 2141, 3406 J. Klensin
Category: Standards Track April 2017
ISSN: 2070-1721
Uniform Resource Names (URNs)
Abstract
A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI)
that is assigned under the "urn" URI scheme and a particular URN
namespace, with the intent that the URN will be a persistent,
location-independent resource identifier. With regard to URN syntax,
this document defines the canonical syntax for URNs (in a way that is
consistent with URI syntax), specifies methods for determining URN-
equivalence, and discusses URI conformance. With regard to URN
namespaces, this document specifies a method for defining a URN
namespace and associating it with a namespace identifier, and it
describes procedures for registering namespace identifiers with the
Internet Assigned Numbers Authority (IANA). This document obsoletes
both RFCs 2141 and 3406.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8141.
Saint-Andre & Klensin Standards Track [Page 1]
RFC 8141 URNs April 2017
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Saint-Andre & Klensin Standards Track [Page 2]
RFC 8141 URNs April 2017
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Design Trade-offs . . . . . . . . . . . . . . . . . . . . 6
1.2.1. Resolution . . . . . . . . . . . . . . . . . . . . . 8
1.2.2. Character Sets and Encodings . . . . . . . . . . . . 9
2. URN Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1. Namespace Identifier (NID) . . . . . . . . . . . . . . . 10
2.2. Namespace Specific String (NSS) . . . . . . . . . . . . . 10
2.3. Optional Components . . . . . . . . . . . . . . . . . . . 12
2.3.1. r-component . . . . . . . . . . . . . . . . . . . . . 12
2.3.2. q-component . . . . . . . . . . . . . . . . . . . . . 13
2.3.3. f-component . . . . . . . . . . . . . . . . . . . . . 15
3. URN-Equivalence . . . . . . . . . . . . . . . . . . . . . . . 16
3.1. Procedure . . . . . . . . . . . . . . . . . . . . . . . . 16
3.2. Examples . . . . . . . . . . . . . . . . . . . . . . . . 17
4. URI Conformance . . . . . . . . . . . . . . . . . . . . . . . 18
4.1. Use in URI Protocol Slots . . . . . . . . . . . . . . . . 18
4.2. Parsing . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.3. URNs and Relative References . . . . . . . . . . . . . . 19
4.4. Transport and Display . . . . . . . . . . . . . . . . . . 19
4.5. URI Design and Ownership . . . . . . . . . . . . . . . . 20
5. URN Namespaces . . . . . . . . . . . . . . . . . . . . . . . 20
5.1. Formal URN Namespaces . . . . . . . . . . . . . . . . . . 22
5.2. Informal URN Namespaces . . . . . . . . . . . . . . . . . 23
6. Defining and Registering a URN Namespace . . . . . . . . . . 24
6.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 24
6.2. Registration Policy and Process: Community Registrations 25
6.3. Registration Policy and Process: Fast Track for Standards
Development Organizations, Scientific Societies, and
Similar Bodies . . . . . . . . . . . . . . . . . . . . . 26
6.4. Completing the Template . . . . . . . . . . . . . . . . . 27
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