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
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)




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.

统一资源名称(URN)是在“URN”URI方案和特定URN命名空间下分配的统一资源标识符(URI),其目的是使URN成为持久的、位置独立的资源标识符。关于URN语法,本文档定义了URN的规范语法(以与URI语法一致的方式),指定了确定URN等价性的方法,并讨论了URI一致性。关于URN名称空间,本文档指定了定义URN名称空间并将其与名称空间标识符关联的方法,并描述了向Internet Assigned Numbers Authority(IANA)注册名称空间标识符的过程。本文件淘汰了RFC 2141和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.

本文件是互联网工程任务组(IETF)的产品。它代表了IETF社区的共识。它已经接受了公众审查,并已被互联网工程指导小组(IESG)批准出版。有关互联网标准的更多信息,请参见RFC 7841第2节。

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at


Copyright Notice


Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved.

版权所有(c)2017 IETF信托基金和确定为文件作者的人员。版权所有。

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents ( in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.

本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(自本文件出版之日起生效。请仔细阅读这些文件,因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本,并提供简化BSD许可证中所述的无担保。

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
       6.4.1.  Purpose . . . . . . . . . . . . . . . . . . . . . . .  27
       6.4.2.  Syntax  . . . . . . . . . . . . . . . . . . . . . . .  28
       6.4.3.  Assignment  . . . . . . . . . . . . . . . . . . . . .  29
       6.4.4.  Security and Privacy  . . . . . . . . . . . . . . . .  29
       6.4.5.  Interoperability  . . . . . . . . . . . . . . . . . .  30
       6.4.6.  Resolution  . . . . . . . . . . . . . . . . . . . . .  30
       6.4.7.  Additional Information  . . . . . . . . . . . . . . .  30
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  31
     7.1.  URI Scheme  . . . . . . . . . . . . . . . . . . . . . . .  31
     7.2.  Registration of URN Namespaces  . . . . . . . . . . . . .  31
     7.3.  Discussion List for New and Updated NID Registrations . .  31
   8.  Security and Privacy Considerations . . . . . . . . . . . . .  32
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  32
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  32
   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
       6.4.1.  Purpose . . . . . . . . . . . . . . . . . . . . . . .  27
       6.4.2.  Syntax  . . . . . . . . . . . . . . . . . . . . . . .  28
       6.4.3.  Assignment  . . . . . . . . . . . . . . . . . . . . .  29
       6.4.4.  Security and Privacy  . . . . . . . . . . . . . . . .  29
       6.4.5.  Interoperability  . . . . . . . . . . . . . . . . . .  30
       6.4.6.  Resolution  . . . . . . . . . . . . . . . . . . . . .  30
       6.4.7.  Additional Information  . . . . . . . . . . . . . . .  30
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  31
     7.1.  URI Scheme  . . . . . . . . . . . . . . . . . . . . . . .  31
     7.2.  Registration of URN Namespaces  . . . . . . . . . . . . .  31
     7.3.  Discussion List for New and Updated NID Registrations . .  31
   8.  Security and Privacy Considerations . . . . . . . . . . . . .  32
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  32
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  32
   Appendix A.  Registration Template  . . . . . . . . . . . . . . .  37
   Appendix B.  Changes from RFC 2141  . . . . . . . . . . . . . . .  38
     B.1.  Syntax Changes from RFC 2141  . . . . . . . . . . . . . .  38
     B.2.  Other Changes from RFC 2141 . . . . . . . . . . . . . . .  39
   Appendix C.  Changes from RFC 3406  . . . . . . . . . . . . . . .  39
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  40
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  40
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40
   Appendix A.  Registration Template  . . . . . . . . . . . . . . .  37
   Appendix B.  Changes from RFC 2141  . . . . . . . . . . . . . . .  38
     B.1.  Syntax Changes from RFC 2141  . . . . . . . . . . . . . .  38
     B.2.  Other Changes from RFC 2141 . . . . . . . . . . . . . . .  39
   Appendix C.  Changes from RFC 3406  . . . . . . . . . . . . . . .  39
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  40
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  40
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40
1. Introduction
1. 介绍

A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) [RFC3986] 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. A URN namespace is a collection of such URNs, each of which is (1) unique, (2) assigned in a consistent and managed way, and (3) assigned according to a common definition. (Some URN namespaces create names that exist only as URNs, whereas others assign URNs based on names that were already created in non-URN identifier systems, such as ISBNs [RFC3187], ISSNs [RFC3044], or RFCs [RFC2648].)


The assignment of URNs is done by an organization (or, in some cases, according to an algorithm or other automated process) that has been formally delegated a URN namespace within the "urn" scheme (e.g., a URN in the "example" URN namespace [RFC6963] might be of the form "urn:example:foo").


This document rests on two key assumptions:


1. Assignment of a URN is a managed process.

1. URN的分配是一个托管过程。

2. The space of URN namespaces is itself managed.

2. URN名称空间的空间本身是受管理的。

While other URI schemes may allow resource identifiers to be freely chosen and assigned, such is not the case for URNs. The syntactical correctness of a name starting with "urn:" is not sufficient to make it a URN. In order for the name to be a valid URN, the namespace identifier (NID) needs to be registered in accordance with the rules defined here, and the remaining parts of the assigned-name portion of the URN need to be generated in accordance with the rules for the registered URN namespace.


So that information about both URN syntax and URN namespaces is available in one place, this document does the following:


1. Defines the canonical syntax for URNs in general (in a way that is consistent with URI syntax), specifies methods for determining URN-equivalence, and discusses URI conformance.

1. 通常定义URN的规范语法(以与URI语法一致的方式),指定确定URN等价性的方法,并讨论URI一致性。

2. Specifies a method for defining a URN namespace and associating it with a particular NID, and describes procedures for registering URN NIDs with the Internet Assigned Numbers Authority (IANA).

2. 指定用于定义URN命名空间并将其与特定NID关联的方法,并描述向Internet Assigned Numbers Authority(IANA)注册URN NID的过程。

For URN syntax and URN namespaces, this document modernizes and replaces the original specifications for URN syntax [RFC2141] and for the definition and registration of URN namespaces [RFC3406]. These modifications build on the key requirements provided in the original functional description for URNs [RFC1737] and on the lessons of many years of experience. In those original documents and in the present one, the intent is to define URNs in a consistent manner so that, wherever practical, the parsing, handling, and resolution of URNs can be independent of the URN namespace within which a given URN is assigned.


Together with input from several key user communities, the history and experiences with URNs dictated expansion of the URN definition to support new functionality, including the use of syntax explicitly reserved for future standardization in RFC 2141. All URN namespaces and URNs that were valid under the earlier specifications remain valid, even though it may be useful to update the definitions of some URN namespaces to take advantage of new features.

结合几个关键用户社区的输入,URN的历史和经验决定了URN定义的扩展,以支持新的功能,包括使用RFC 2141中明确保留用于未来标准化的语法。根据早期规范有效的所有URN名称空间和URN仍然有效,即使更新某些URN名称空间的定义以利用新功能可能很有用。

The foregoing considerations, together with various differences between URNs and URIs that are locators (specifically URLs) as well as the greater focus on URLs in RFC 3986 as the ultimate successor to [RFC1738] and [RFC1808], may lead to some interpretations of RFC 3986 and this specification that appear (or perhaps actually are) not completely consistent, especially with regard to actions or semantics other than the basic syntax itself. If such situations arise, discussions of URNs and URN namespaces should be interpreted according to this document and not by extrapolation from RFC 3986.

上述考虑因素,加上URN和URI之间作为定位器(特别是URL)的各种差异,以及作为[RFC1738]和[RFC1808]的最终继承者,RFC 3986中对URL的更多关注,可能会导致对RFC 3986和本规范的一些解释出现(或可能实际出现)不完全一致,特别是在基本语法本身以外的动作或语义方面。如果出现这种情况,应根据本文件解释URN和URN名称空间的讨论,而不是根据RFC 3986推断。

Summaries of changes from RFCs 2141 and 3406 appear in Appendices B and C, respectively. This document obsoletes both [RFC2141] and [RFC3406]. While it does not explicitly update or replace [RFC1737] or [RFC2276], the reader who references those documents should be aware that the conceptual model of URNs in this document is slightly different from those older specifications.

RFC 2141和3406的变更摘要分别见附录B和C。本文件废除了[RFC2141]和[RFC3406]。虽然没有明确更新或替换[RFC1737]或[RFC2276],但参考这些文档的读者应该知道,本文档中的URN概念模型与那些旧规范略有不同。

1.1. Terminology
1.1. 术语

The following terms are distinguished from each other as described below:


URN: A URI (as defined in RFC 3986) using the "urn" scheme and with the properties of a "name" as described in that document as well as the properties described in this one. The term applies to the entire URI including its optional components. Note to the reader: the term "URN" has been used in other contexts to refer to a URN namespace, the namespace identifier, the assigned-name, and URIs that do not use the "urn" scheme. All but the last of these is described using more specific terminology elsewhere in this document, but, because of those other uses, the term should be used and interpreted with care.


Locator: An identifier that provides a means of accessing a resource.


Identifier system: A managed collection of names. This document refers to identifier systems outside the context of URNs as "non-URN identifier systems".


URN namespace: An identifier system that is associated with a URN NID.

URN命名空间:与URN NID关联的标识符系统。

NID: The identifier associated with a URN namespace.


NSS: The URN-namespace-specific part of a URN.


Assigned-name: The combination of the "urn:" scheme, the NID, and the namespace specific string (NSS). An "assigned-name" is consequently a substring of a URN (as defined above) if that URN contains any additional components (see Section 2).


The term "name" is deliberately not defined here and should be (and, in practice, is) used only very informally. RFC 3986 uses the term as a category of URI distinguished from "locator" (Section 1.1.3) but also uses it in other contexts. If those uses are treated as definitional, they would conflict with, e.g., the idea of URN namespace names (i.e., NIDs) and with terms associated with non-URN identifier systems.

这里故意不定义术语“名称”,而应该(实际上)非常非正式地使用。RFC 3986使用该术语作为URI的一个类别,区别于“定位器”(第1.1.3节),但也在其他上下文中使用它。如果这些使用被视为定义性的,它们将与URN名称空间名称(即NID)的概念以及与非URN标识符系统相关的术语相冲突。

This document uses the terms "resource", "identifier", "identify", "dereference", "representation", and "metadata" roughly as defined in the URI specification [RFC3986].


This document uses the terms "resolution" and "resolver" in roughly the sense in which they were used in the original discussion of architectural principles for URNs [RFC2276], i.e., "resolution" is the act of supplying services related to the identified resource, such as translating the persistent URN into one or more current locators for the resource, delivering metadata about the resource in an appropriate format, or even delivering a representation of the resource (e.g., a document) without requiring further intermediaries. At the time of this writing, resolution services are described in [RFC2483].


On the distinction between representations and metadata, see Section 1.2.2 of [RFC3986].


Several other terms related to "normalization" operations that are not part of the Unicode Standard [UNICODE] are also used here as they are in RFC 3986.

与“规范化”操作相关的其他几个术语不属于Unicode标准[Unicode]的一部分,它们在RFC 3986中也被使用。

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].


1.2. Design Trade-offs
1.2. 设计权衡

To a degree much greater than when URNs were first considered and their uses outlined (see [RFC1737]), issues of persistent identifiers on the Internet involve fundamental design trade-offs that are much broader than URNs or the URN approach and even touch on open research questions within the information sciences community. Ideal and comprehensive specifications about what should be done or required across the entire universe of URNs would require general agreement about, and solutions to, a wide range of such issues. Although some of those issues were introduced by the Internet or computer-age approaches to character encodings and data abstraction, others predate the Internet and computer systems by centuries; there is unlikely to be agreement about comprehensive solutions in the near future.


Although this specification consequently contains some requirements and flexibility that would not be present in a more perfect world, this has been necessary in order to produce a consensus specification that provides a modernized definition of URNs (the unattractive alternative would have been to not modernize the definition in spite of widespread deployment).


The following sub-sections describe two of the relevant issues in greater detail.


1.2.1. Resolution
1.2.1. 决议

One issue that is specific to URNs (as opposed to naming systems in general) is the fairly difficult topic of "resolution", discussed in Sections 1.1, 2.3.1, 6.4.6, and elsewhere below.


With traditional Uniform Resource Locators (URLs), i.e., with most URIs that are locators, resolution is relatively straightforward because it is used to determine an access mechanism that in turn is used to dereference the locator by (typically) retrieving a representation of the associated resource, such as a document (see Section 1.2.2 of [RFC3986]).


By contrast, resolution for URNs is more flexible and varied.


One important case involves the mapping of a URN to one or more locators. In this case, the end result is still a matter of dereferencing the mapped locator(s) to one or more representations. The primary difference here is persistence: even if a mapped locator has changed (e.g., a DNS domain name has changed hands and a URL has not been modified to point to a new location or, in a more extreme and hypothetical case, the DNS is replaced entirely), a URN user will be able to obtain the correct representation (e.g., a document) as long as the resolver has kept its URN-to-locator mappings up to date. Consequently, the relevant relationships can be defined quite precisely for URNs that resolve to locators that in turn are dereferenced to a representation.


However, this specification permits several other cases of URN resolution as well as URNs for resources that do not involve information retrieval systems. This is true either individually for particular URNs or (as defined below) collectively for entire URN namespaces.


Consider a namespace of URNs that resolve to locators that in turn are dereferenced only to metadata about resources because the underlying systems contain no representations of those resources; an example might be a URN namespace for International Standard Name Identifiers (ISNIs) as that identifier system is defined in the relevant standard [ISO.27729.2012], wherein by default a URN would be resolved only to a metadata record describing the public identity identified by the ISNI.


Consider also URNs that resolve to representations only if the requesting entity is authorized to obtain the representation, whereas other entities can obtain only metadata about the resource; an example might be documents held within the legal depository collection of a national library.


Finally, some URNs might not be intended to resolve to locators at all; examples might include URNs identifying XML namespace names (e.g., the "dgiwg" URN namespace specified by [RFC6288]), URNs identifying application features that can be supported within a communications protocol (e.g., the "alert" URN namespace specified by [RFC7462]), and URNs identifying enumerated types such as values in a registry (e.g., a URN namespace could be used to individually identify the values in all IANA registries, as provisionally proposed in [IANA-URN]).


Various types of URNs and multiple resolution services that may be available for them leave the concept of "resolution" more complicated but also much richer for URNs than the straightforward case of resolution to a locator that is dereferenced to a representation.


1.2.2. Character Sets and Encodings
1.2.2. 字符集和编码

A similar set of considerations apply to character sets and encodings. URNs, especially URNs that will be used as user-facing identifiers, should be convenient to use in local languages and writing systems, easily specified with a wide range of keyboards and local conventions, and unambiguous. There are trade-offs among those goals, and it is impossible at present to see how a simple and readily understandable set of rules could be developed that would be optimal, or even reasonable, for all URNs. The discussion in Section 2.2 defines an overall framework that should make generalized parsing and processing possible but also makes recommendations about rules for individual URN namespaces.


2. URN Syntax
2. URN语法

As discussed above, the syntax for URNs in this specification allows significantly more functionality than was the case in the earlier specifications, most recently [RFC2141]. It is also harmonized with the general URI syntax [RFC3986] (which, it must be noted, was completed after the earlier URN specifications).


However, this specification does not extend the URN syntax to allow direct use of characters outside the ASCII range [RFC20]. That restriction implies that any such characters need to be percent-encoded as described in Section 2.1 of the URI specification [RFC3986].


The basic syntax for a URN is defined using the Augmented Backus-Naur Form (ABNF) as specified in [RFC5234]. Rules not defined here (specifically: alphanum, fragment, and pchar) are defined as part of the URI syntax [RFC3986] and used here to point out the syntactic relationship with the terms used there. The definitions of some of


the terms used below are not comprehensive; additional restrictions are imposed by the prose that can be found in sections of this document that are specific to those terms (especially r-component in Section 2.3.1 and q-component in Section 2.3.2).


      namestring    = assigned-name
                      [ rq-components ]
                      [ "#" f-component ]
      assigned-name = "urn" ":" NID ":" NSS
      NID           = (alphanum) 0*30(ldh) (alphanum)
      ldh           = alphanum / "-"
      NSS           = pchar *(pchar / "/")
      rq-components = [ "?+" r-component ]
                      [ "?=" q-component ]
      r-component   = pchar *( pchar / "/" / "?" )
      q-component   = pchar *( pchar / "/" / "?" )
      f-component   = fragment
      namestring    = assigned-name
                      [ rq-components ]
                      [ "#" f-component ]
      assigned-name = "urn" ":" NID ":" NSS
      NID           = (alphanum) 0*30(ldh) (alphanum)
      ldh           = alphanum / "-"
      NSS           = pchar *(pchar / "/")
      rq-components = [ "?+" r-component ]
                      [ "?=" q-component ]
      r-component   = pchar *( pchar / "/" / "?" )
      q-component   = pchar *( pchar / "/" / "?" )
      f-component   = fragment

The question mark character "?" can be used without percent-encoding inside r-components, q-components, and f-components. Other than inside those components, a "?" that is not immediately followed by "=" or "+" is not defined for URNs and SHOULD be treated as a syntax error by URN-specific parsers and other processors.


The following sections provide additional information about the syntactic elements of URNs.


2.1. Namespace Identifier (NID)
2.1. 名称空间标识符(NID)

NIDs are case insensitive (e.g., "ISBN" and "isbn" are equivalent).


Characters outside the ASCII range [RFC20] are not permitted in NIDs, and no encoding mechanism for such characters is supported.


Sections 5.1 and 5.2 impose additional constraints on the strings that can be used as NIDs, i.e., the syntax shown above is not comprehensive.


2.2. Namespace Specific String (NSS)
2.2. 命名空间特定字符串(NSS)

The NSS is a string, unique within a URN namespace, that is assigned and managed in a consistent way and that conforms to the definition of the relevant URN namespace. The combination of the NID (unique across the entire "urn" scheme) and the NSS (unique within the URN namespace) ensures that the resulting URN is globally unique.


The NSS as specified in this document allows several characters not permitted by earlier specifications (see Appendix B). In particular, the "/" character, which is now allowed, effectively makes it possible to encapsulate hierarchical names from non-URN identifier systems. For instance, consider the hypothetical example of a hierarchical identifier system in which the names take the form of a sequence of numbers separated by the "/" character, such as "1/406/47452/2". If the authority for such names were to use URNs, it would be natural to place the existing name in the NSS, resulting in URNs such as "urn:example:1/406/47452/2".


Those changes to the syntax for the NSS do not modify the encoding rules for URN namespaces that were defined in accordance with [RFC2141]. If any such URN namespace whose names are used outside of the URN context (i.e., in a non-URN identifier system) also allows the use of "/", "~", or "&" in the native form within that identifier system, then the encoding rules for that URN namespace are not changed by this specification.


Depending on the rules governing a non-URN identifier system and its associated URN namespace, names that are valid in that identifier system might contain characters that are not allowed by the "pchar" production referenced above (e.g., characters outside the ASCII range or, consistent with the restrictions in RFC 3986, the characters "/", "?", "#", "[", and "]"). While such a name might be valid within the non-URN identifier system, it is not a valid URN until it has been translated into an NSS that conforms to the rules of that particular URN namespace. In the case of URNs that are formed from names that exist separately in a non-URN identifier system, translation of a name from its "native" format to a URN format is accomplished by using the canonicalization and encoding methods defined for URNs in general or specific rules for that URN namespace. Software that is not aware of namespace-specific canonicalization and encoding rules MUST NOT construct URNs from the name in the non-URN identifier system.

根据管理非URN标识符系统及其关联URN命名空间的规则,在该标识符系统中有效的名称可能包含上面引用的“pchar”产品不允许的字符(例如,ASCII范围之外的字符,或者符合RFC 3986中的限制,字符“/”、“?”,“#”、“[”和“]”。虽然此名称在非URN标识符系统中可能有效,但在转换为符合该特定URN命名空间规则的NSS之前,它不是有效的URN。如果URN是由非URN标识符系统中单独存在的名称组成的,则从其URN格式的“本机”格式是通过使用为URN定义的规范化和编码方法(通用或该URN命名空间的特定规则)来实现的。不知道特定于命名空间的规范化和编码规则的软件不得从非URN标识符系统中的名称构造URN。

In particular, with regard to characters outside the ASCII range, URNs that appear in protocols or that are passed between systems MUST use only Unicode characters encoded in UTF-8 and further encoded as required by RFC 3986. To the extent feasible and consistent with the requirements of names defined and standardized elsewhere, as well as the principles discussed in Section 1.2, the characters used to represent names SHOULD be restricted to either ASCII letters and digits or to the characters and syntax of some widely used models such as those of Internationalizing Domain Names in Applications (IDNA) [RFC5890], Preparation, Enforcement, and Comparison of Internationalized Strings (PRECIS) [RFC7613], or the Unicode Identifier and Pattern Syntax specification [UAX31].

特别是,对于ASCII范围之外的字符,出现在协议中或在系统之间传递的URN必须仅使用UTF-8编码的Unicode字符,并按照RFC 3986的要求进一步编码。在可行且符合其他地方定义和标准化的名称要求以及第1.2节讨论的原则的情况下,用于表示名称的字符应限制为ASCII字母和数字或一些广泛使用的模型的字符和语法,如应用程序中的国际化域名(IDNA)[RFC5890],国际化字符串的准备、实施和比较(PRECIS)[RFC7613],或Unicode标识符和模式语法规范[UAX31]。

In order to make URNs as stable and persistent as possible when protocols evolve and the environment around them changes, URN namespaces SHOULD NOT allow characters outside the ASCII range [RFC20] unless the nature of the particular URN namespace makes such characters necessary.


2.3. Optional Components
2.3. 可选组件

This specification includes three optional components in the URN syntax. They are known as r-component, q-component, and f-component and are described in more detail below. Because this specification focuses almost exclusively on URN syntax, it does not define detailed semantics of these components for URNs in general. However, each of these components has a distinct role that is independent of any given URN and its URN namespace. It is intended that clients will be able to handle these components uniformly for all URNs. These components MAY be used with URNs from existing URN namespaces, whether or not a URN namespace explicitly supports them. However, consistent with the approach taken in RFC 3986, the behavior of a URN that contains components that are undefined or meaningless for a particular URN namespace or resource is not defined. The following sections describe these optional components and their interpretation in greater detail.

本规范包括URN语法中的三个可选组件。它们被称为r分量、q分量和f分量,下面将对它们进行更详细的描述。由于本规范几乎只关注URN语法,因此通常不为URN定义这些组件的详细语义。但是,这些组件中的每一个都有一个独立于任何给定URN及其URN命名空间的独特角色。其目的是使客户能够为所有URN统一处理这些组件。这些组件可以与现有URN命名空间中的URN一起使用,无论URN命名空间是否明确支持它们。但是,与RFC 3986中采用的方法一致,未定义包含未定义或对特定URN命名空间或资源没有意义的组件的URN的行为。以下各节将更详细地描述这些可选组件及其解释。

2.3.1. r-component
2.3.1. r分量

The r-component is intended for passing parameters to URN resolution services (taken broadly, see Section 1.2) and interpreted by those services. (By contrast, passing parameters to the resources identified by a URN, or to applications that manage such resources, is handled by q-components as described in the next section.)


The URN r-component has no syntactic counterpart in any other known URI scheme.

URN r组件在任何其他已知URI方案中都没有语法对应项。

The sequence "?+" introduces the r-component. The r-component ends with a "?=" sequence (which begins a q-component) or a "#" character (number sign, which begins an f-component). If neither of those appear, the r-component continues to the end of the URN. Note that characters outside the ASCII range [RFC20] MUST be percent-encoded using the method defined in Section 2.1 of the generic URI specification [RFC3986].


As described in Section 3, the r-component SHALL NOT be taken into account when determining URN-equivalence. However, the r-component SHALL be supplied along with the URN when presenting a request to a URN resolution service.


This document defines only the syntax of the r-component and reserves it for future use. The exact semantics of the r-component and its use in URN resolution protocols are a matter for potential standardization in separate specifications, presumably including specifications that define conventions and a registry for resolution service identifiers.


Consider the hypothetical example of passing parameters to a resolution service (say, an ISO alpha-2 country code [ISO.3166-1] in order to select the preferred country in which to search for a physical copy of a book). This could perhaps be accomplished by specifying the country code in the r-component, resulting in URNs such as:

考虑将参数传递给解决服务的假设示例(例如,ISO 2国家代码[ISO 3166-1),以便选择在其中搜索一本书的物理副本的首选国家)。这可以通过在r组件中指定国家代码来实现,从而生成URN,例如:


While the above should serve as a general explanation and illustration of the intent for r-components, there are many open issues with them, including their relationship to resolution mechanisms associated with the particular URN namespace at registration time. Thus, r-components SHOULD NOT be used for URNs before their semantics have been standardized.


2.3.2. q-component
2.3.2. q分量

The q-component is intended for passing parameters to either the named resource or a system that can supply the requested service, for interpretation by that resource or system. (By contrast, passing parameters to URN resolution services is handled by r-components as described in the previous section.)

q组件用于将参数传递给命名资源或可提供所请求服务的系统,以便该资源或系统进行解释。(相反,将参数传递给URN resolution services由r组件处理,如前一节所述。)

The URN q-component has the same syntax as the URI query component but is introduced by "?=", not "?" alone. For a URN that may be resolved to a URI that is a locator, the semantics of the q-component are identical to those for the query component of that URI. Thus, URN resolvers returning a URI that is a locator for a URN with a q-component do this by copying the q-component from the URN to the query component of the URI. An example of the copying operation appears below.

URN q组件与URI查询组件具有相同的语法,但由“?=”引入,而不是仅由“?”引入。对于可以解析为作为定位器的URI的URN,q组件的语义与该URI的查询组件的语义相同。因此,返回URI的URN解析器通过将q组件从URN复制到URI的查询组件来实现这一点,该URI是带有q组件的URN的定位器。下面是复制操作的一个示例。

This specification does not specify a required behavior in the case of URN resolution to a URI that is a locator when the original URN has a q-component and the URI has a query string. Different circumstances may require different approaches. Resolvers SHOULD document their strategy in such cases.


If the URN does not resolve to a URI that is a locator, the interpretation of the q-component is undefined by this specification. For URNs that may be resolved to a URI that is a locator, the semantics of the q-component are identical to those for queries to the resource located via that URI.


For the sake of consistency with RFC 3986, the general syntax and the semantics of q-components are not defined by, or dependent on, the URN namespace of the URN. In parallel with RFC 3986, specifics of syntax and semantics, e.g., which keywords or terms are meaningful, of course may depend on a particular URN namespace or even a particular resource.

为了与RFC 3986保持一致,q组件的一般语法和语义不由URN的URN命名空间定义或依赖于URN命名空间。与RFC 3986并行,语法和语义的细节,例如,哪些关键字或术语有意义,当然可能取决于特定的URN名称空间甚至特定的资源。

The sequence "?=" introduces the q-component. The q-component ends with a "#" character (number sign, which begins an f-component). If that character does not appear, the q-component continues to the end of the URN. The characters slash ("/") and question mark ("?") may represent data within the q-component. Note that characters outside the ASCII range [RFC20] MUST be percent-encoded using the method defined in Section 2.1 of the generic URI specification [RFC3986].


As described in Section 3, the q-component SHALL NOT be taken into account when determining URN-equivalence.


URN namespaces and associated information placement in syntax SHOULD be designed to avoid any need for a resolution service to consider the q-component. Namespace-specific and more generic resolution systems MUST NOT require that q-component information be passed to them for processing.


Consider the hypothetical example of passing parameters to an application that returns weather reports from different regions or for different time periods. This could perhaps be accomplished by specifying latitude and longitude coordinates and datetimes in the URN's q-component, resulting in URNs such as the following.



If this example resolved to an HTTP URI, the result might look like:

如果此示例解析为HTTP URI,则结果可能如下所示:

2.3.3. f-component
2.3.3. f分量

The f-component is intended to be interpreted by the client as a specification for a location within, or region of, the named resource. It distinguishes the constituent parts of a resource named by a URN. For a URN that resolves to one or more locators that can be dereferenced to a representation, or where the URN resolver directly returns a representation of the resource, the semantics of an f-component are defined by the media type of the representation.


The URN f-component has the same syntax as the URI fragment component. If a URN containing an f-component resolves to a single URI that is a locator associated with the named resource, the f-component from the URN can be applied (usually by the client) as the fragment of that URI. If the URN does not resolve to a URI that is a locator, the interpretation of the f-component is undefined by this specification. Thus, for URNs that may be resolved to a URI that is a locator, the semantics of f-components are identical to those of fragments for that resource.

URN f组件与URI片段组件具有相同的语法。如果包含f组件的URN解析为单个URI,该URI是与命名资源关联的定位器,则可以(通常由客户端)将URN中的f组件作为该URI的片段应用。如果URN未解析为作为定位器的URI,则本规范未定义f组件的解释。因此,对于可以解析为作为定位器的URI的URN,f组件的语义与该资源的片段的语义相同。

For the sake of consistency with RFC 3986, neither the general syntax nor the semantics of f-components are defined by, or dependent on, the URN namespace of the URN. In parallel with RFC 3986, specifics of syntax and semantics, e.g., which keywords or terms are meaningful, of course may depend on a particular URN namespace or even a particular resource.

为了与RFC 3986保持一致,f组件的一般语法和语义都不是由URN的URN命名空间定义的,也不是依赖于URN命名空间的。与RFC 3986并行,语法和语义的细节,例如,哪些关键字或术语有意义,当然可能取决于特定的URN名称空间甚至特定的资源。

The f-component is introduced by the number sign ("#") character and terminated by the end of the URI. Any characters outside the ASCII range [RFC20] that appear in the f-component MUST be percent-encoded using the method defined in Section 2.1 of the generic URI specification [RFC3986].


As described in Section 3, the f-component SHALL NOT be taken into account when determining URN-equivalence.


Clients SHOULD NOT pass f-components to resolution services unless those services also perform object retrieval and interpretation functions.


Consider the hypothetical example of obtaining resources that are part of a larger entity (say, the chapters of a book). Each part could be specified in the f-component, resulting in URNs such as:


3. URN-Equivalence
3. 瓮等效
3.1. Procedure
3.1. 程序

For various purposes such as caching, it is often desirable to determine if two URNs are "the same". This is done most generally (i.e., independent of the scheme) by testing for equivalence (see Section 6.1 of [RFC3986]).


The generic URI specification [RFC3986] is very flexible about equality comparisons, putting the focus on allowing false negatives and avoiding false positives. If comparisons are made in a scheme-independent way, i.e., as URI comparisons only, many URNs that this specification considers equal would be rejected. The discussion below applies when the URIs involved are known to be URNs and thus uses the terms "URN-equivalent" and "URN-equivalence" to refer to equivalence as specified in this document.


Two URNs are URN-equivalent if their assigned-name portions are octet-by-octet equal after applying case normalization (as specified in Section of [RFC3986]) to the following constructs:


1. the URI scheme "urn", by conversion to lower case

1. URI方案“urn”,通过转换为小写

2. the NID, by conversion to lower case

2. NID,通过转换为小写

3. any percent-encoded characters in the NSS (that is, all character triplets that match the <pct-encoding> production found in Section 2.1 of the base URI specification [RFC3986]), by conversion to upper case for the digits A-F.

3. NSS中的任何百分比编码字符(即,与基本URI规范[RFC3986]第2.1节中的<pct encoding>产品相匹配的所有字符三元组),通过将数字A-F转换为大写。

Percent-encoded characters MUST NOT be decoded, i.e., percent-encoding normalization (as specified in Section of [RFC3986]) MUST NOT be applied as part of the comparison process.


If an r-component, q-component, or f-component (or any combination thereof) is included in a URN, it MUST be ignored for purposes of determining URN-equivalence.


URN namespace definitions MAY include additional rules for URN-equivalence, such as case insensitivity of the NSS (or parts thereof). Such rules MUST always have the effect of eliminating some of the false negatives obtained by the procedure above and MUST NOT result in treating two URNs as not "the same" if the procedure here says they are URN-equivalent. For related considerations with regard to NID registration, see below.


3.2. Examples
3.2. 例子

This section shows a variety of URNs (using the "example" NID defined in [RFC6963]) that highlight the URN-equivalence rules.


First, because the scheme and NID are case insensitive, the following three URNs are URN-equivalent to each other:


o urn:example:a123,z456

o 瓮:示例:a123,z456

o URN:example:a123,z456

o 瓮:示例:a123,z456

o urn:EXAMPLE:a123,z456

o 瓮:示例:a123,z456

Second, because the r-component, q-component, and f-component are not taken into account for purposes of testing URN-equivalence, the following three URNs are URN-equivalent to the first three examples above:


o urn:example:a123,z456?+abc

o 瓮:示例:a123,z456?+abc

o urn:example:a123,z456?=xyz

o urn:示例:a123,z456?=xyz

o urn:example:a123,z456#789

o 瓮:示例:a123,z456#789

Third, because the "/" character (and anything that follows it) in the NSS is taken into account for purposes of URN-equivalence, the following URNs are not URN-equivalent to each other or to the six preceding URNs:


o urn:example:a123,z456/foo

o urn:example:a123,z456/foo

o urn:example:a123,z456/bar

o 瓮:示例:a123,z456/巴

o urn:example:a123,z456/baz

o 瓮:示例:a123、z456/baz

Fourth, because of percent-encoding, the following URNs are URN-equivalent only to each other and not to any of those above (note that, although %2C is the percent-encoded transformation of "," from the previous examples, such sequences are not decoded for purposes of testing URN-equivalence):


o urn:example:a123%2Cz456

o urn:示例:a123%2Cz456

o URN:EXAMPLE:a123%2cz456

o URN:示例:a123%2cz456

Fifth, because characters in the NSS other than percent-encoded sequences are treated in a case-sensitive manner (unless otherwise specified for the URN namespace in question), the following URNs are not URN-equivalent to the first three URNs:


o urn:example:A123,z456

o 瓮:示例:A123,z456

o urn:example:a123,Z456

o 瓮:示例:a123,Z456

Sixth, on casual visual inspection of a URN presented in a human-oriented interface, the following URN might appear the same as the first three URNs (because U+0430 CYRILLIC SMALL LETTER A can be confused with U+0061 LATIN SMALL LETTER A), but it is not URN-equivalent to the first three URNs:


o urn:example:%D0%B0123,z456

o urn:示例:%D0%B0123,z456

4. URI Conformance
4. URI一致性
4.1. Use in URI Protocol Slots
4.1. 在URI协议插槽中使用

Because a URN is, syntactically, a URI under the "urn" scheme, in theory a URN can be placed in any protocol slot that allows for a URI (to name just a few, the "href" and "src" attributes in HTML, the base element in HTML, the "xml:base" attribute in XML [XML-BASE], and the "xmlns" attribute in XML for XML namespace names [XML-NAMES]).


However, this does not imply that, semantically, it always makes sense in practice to place a URN in a given URI protocol slot; in particular, because a URN might not specify the location of a resource or even point indirectly to one, it might not be appropriate to place a URN in a URI protocol slot that points to a resource (e.g., the aforementioned "href" and "src" attributes).


Ultimately, guidelines regarding when it is appropriate to use URIs under the "urn" scheme (or any other scheme) are the responsibility of specifications for individual URI protocol slots (e.g., the specification for the "xml:base" attribute in XML might recommend that it is inappropriate to use URNs in that protocol slot). This specification cannot possibly anticipate all of the relevant cases, and it is not the place of this specification to require or restrict usage for individual protocol slots.


4.2. Parsing
4.2. 解析

In part because of the separation of URN semantics from more general URI syntax, generic URI processors need to pay special attention to the parsing and analysis rules of RFC 3986 and, in particular, must treat the URI as opaque unless the scheme and its requirements are recognized. In the latter case, such processors may be in a position to invoke scheme-appropriate processing, e.g., by a URN resolver. A URN resolver can either be an external resolver that the URI resolver knows of or be functionality built into the URI resolver. Note that this requirement might impose constraints on the contexts in which URNs are appropriately used; see Section 4.1.

部分原因是URN语义与更通用的URI语法分离,通用URI处理器需要特别注意RFC 3986的解析和分析规则,特别是必须将URI视为不透明的,除非方案及其要求得到认可。在后一种情况下,这样的处理器可以调用方案适当的处理,例如通过URN解析器。URN解析器可以是URI解析器知道的外部解析器,也可以是内置于URI解析器中的功能。请注意,此要求可能会对适当使用URN的上下文施加限制;见第4.1节。

4.3. URNs and Relative References
4.3. 骨灰盒和相关参考文献

Section 5.2 of [RFC3986] describes an algorithm for converting a URI reference that might be relative to a given base URI into "parsed components" of the target of that reference, which can then be recomposed per RFC 3986, Section 5.3 into a target URI. This algorithm is problematic for URNs because their syntax does not support the necessary path components. However, if the algorithm is applied independent of a particular scheme, it should work predictably for URNs as well, with the following understandings (syntax production terminology taken from RFC 3986):

[RFC3986]第5.2节描述了一种算法,用于将可能与给定基本URI相关的URI引用转换为该引用目标的“已解析组件”,然后可根据RFC 3986第5.3节将其重新组合为目标URI。此算法对于URN是有问题的,因为它们的语法不支持必要的路径组件。但是,如果该算法独立于特定方案应用,则它也应可预测地适用于URN,并具有以下理解(语法生成术语取自RFC 3986):

1. A system that encounters a <URI-reference> that obeys the syntax for <relative-ref>, whether it explicitly has the scheme "urn" or not, will convert it into a target URI as specified in RFC 3986.

1. 遇到符合<relative ref>语法的<URI reference>的系统,无论其是否显式具有方案“urn”,都会将其转换为RFC 3986中指定的目标URI。

2. Because of the persistence and stability expectations of URNs, authors of documents, etc., that utilize URNs should generally avoid the use of the "urn" scheme in any <URI-reference> that is not strictly a <URI> as specified in RFC 3986, specifically including those that would require processing of <relative-ref>.

2. 由于对urn的持久性和稳定性的期望,使用urn的文档作者等通常应避免在任何<URI reference>中使用“urn”方案,该<URI reference>不是RFC 3986中规定的严格<URI>,具体包括那些需要处理<relative ref>的方案。

4.4. Transport and Display
4.4. 运输及展示

When URNs are transported and exchanged, they MUST be represented in the format defined herein. Further, URN-aware applications are strongly encouraged to offer the option of displaying URNs in this canonical form to allow for direct transcription (for example by copy-and-paste techniques). Such applications might support the display of URNs in a more human-friendly form and might use a character set that includes characters that are not permitted in URN syntax as defined in this specification (e.g., when displaying URNs to humans, such applications might replace percent-encoded strings with characters from an extended character repertoire such as Unicode [UNICODE]).


To minimize user confusion, any application displaying URIs SHOULD display the complete URI (including, for URNs, the "urn" scheme and any components) to ensure that there is no confusion between URN NIDs and URI scheme identifiers. For example, a URI beginning with "urn:xmpp:" [RFC4854] is very different from a URI beginning with "xmpp:" [RFC5122]. Similarly, a potential Digital Object Identifier (DOI) URI scheme [DOI-URI] is different from, and possibly completely unrelated to, a possible DOI URN namespace.

为了尽量减少用户混淆,任何显示URI的应用程序都应该显示完整的URI(对于urn,包括“urn”方案和任何组件),以确保urn NID和URI方案标识符之间没有混淆。例如,以“urn:xmpp:[RFC4854]开头的URI与以“xmpp:[RFC5122]开头的URI非常不同。类似地,潜在的数字对象标识符(DOI)URI方案[DOI-URI]与可能的DOI-URN名称空间不同,并且可能完全无关。

4.5. URI Design and Ownership
4.5. URI设计和所有权

As mentioned, the assignment of URNs within a URN namespace is a managed process, as is the assignment of URN namespaces themselves. Although design of the URNs to be assigned within a given URN namespace is ceded by this specification to the URN namespace manager, doing so in a managed way avoids the problems inherent in unmanaged generation of URIs as described in the recommendations regarding URI design and ownership [RFC7320].


5. URN Namespaces
5. URN名称空间

A URN namespace is a collection of names that obey three constraints: each name is (1) unique, (2) assigned in a consistent way, and (3) assigned according to a common definition.


1. The "uniqueness" constraint means that a name within the URN namespace is never assigned to more than one resource and never reassigned to a different resource (for the kind of "resource" identified by URNs assigned within the URN namespace). This holds true even if the name itself is deprecated or becomes obsolete.

1. “唯一性”约束意味着URN命名空间中的名称从未分配给多个资源,也从未重新分配给其他资源(对于在URN命名空间中分配的URN标识的“资源”类型)。即使名称本身已被弃用或已过时,这一点仍然成立。

2. The "consistent assignment" constraint means that a name within the URN namespace is assigned by an organization or created in accordance with a process or algorithm that is always followed.

2. “一致分配”约束意味着URN命名空间中的名称由组织分配或根据始终遵循的流程或算法创建。

3. The "common definition" constraint means that there are clear definitions for the syntax of names within the URN namespace and for the process of assigning or creating them.

3. “公共定义”约束意味着对URN名称空间中的名称语法以及分配或创建名称的过程有明确的定义。

A URN namespace is identified by a particular NID in order to ensure the global uniqueness of URNs and, optionally, to provide a cue regarding the structure of URNs assigned within a URN namespace.


With regard to global uniqueness, using different NIDs for different collections of names ensures that no two URNs will be the same for different resources, because each collection is required to uniquely assign each name. However, a single resource MAY have more than one


URN assigned to it, either in the same URN namespace (if the URN namespace permits it) or in different URN namespaces, and for either similar purposes or different purposes. (For example, if a publisher assigns an ISBN [RFC3187] to an electronic publication and that publication is later incorporated into a digital long-term archive operated by a national library, the library might assign the publication a national bibliography number (NBN) [RFC3188], resulting in two URNs referring to the same book.) Subject to other constraints, such as those imposed by the URI syntax [RFC3986], the rules of the URN scheme are intended to allow preserving the normal and natural form of names specified in non-URN identifier systems when they are treated as URNs.


With regard to the structure of names assigned within a URN namespace, the development of a naming structure (and thereby a collection of names) depends on the requirements of the community defining the names, how the names will be assigned and used, etc. These issues are beyond the scope of URN syntax and the general rules for URN namespaces, because they are specific to the community defining a non-URN identifier system or a particular URN namespace (e.g., the bibliographic and publishing communities in the case of the "ISBN" URN namespace [RFC3187] and the "ISSN" URN namespace [RFC3044] or the developers of extensions to the Extensible Messaging and Presence Protocol [RFC6120] in the case of the "XMPP" URN namespace [RFC4854]).


Because the colon character (":") is used to separate "urn" from the NID and the NID from the NSS, it's tempting to think of the entire URN as being structured by colon characters and to assume that colons create a structure or hierarchy within the NSS portion of the URN. Such structure could be specified by a particular NID specification, but there is no implicit structure. In a URN such as



the NSS string is "apple:pear:plum:cherry" as a whole, and there is no specific meaning to the colon characters within that NSS string unless such meaning is described in the specification of the "example" namespace.


URN namespaces inherit certain rights and responsibilities by the nature of URNs, in particular:


1. They uphold the general principles of a well-managed URN namespace by providing persistent identification of resources and unique assignment of names in accordance with a common definition.

1. 它们支持管理良好的URN名称空间的一般原则,根据通用定义提供持久的资源标识和唯一的名称分配。

2. Optionally, they can be registered in global registration services such as those described in [RFC2483].

2. 或者,它们可以在全局注册服务中注册,如[RFC2483]中所述。

There are two types of URN namespaces: formal and informal. These are distinguished by the expected level of service, the information needed to define the URN namespace, and the procedures for registration. Because the majority of the URN namespaces registered so far have been formal, this document concentrates on formal URN namespaces.


5.1. Formal URN Namespaces
5.1. 形式URN名称空间

A formal URN namespace provides benefit to some subset of users on the Internet. In particular, it would not make sense for a formal URN namespace to be used only by a community or network that is not connected to the Internet. For example, it would be inappropriate for a URN namespace to effectively force someone to use a proprietary network or service not open to the general Internet user. The intent is that, while the community of those who might actively use the URNs assigned within that URN namespace might be small, the potential use of names within that URN namespace is open to any user on the Internet. Formal URN namespaces might be appropriate even when some aspects are not fully open. For example, a URN namespace might make use of a fee-based, privately managed, or proprietary registry for assignment of URNs in the URN namespace. However, it might still benefit some Internet users if the associated services have openly published names.


An organization that will assign URNs within a formal URN namespace SHOULD meet the following criteria:


1. Organizational stability and the ability to maintain the URN namespace for a long time; absent such evidence, it ought to be clear how the URN namespace can remain viable if the organization can no longer maintain the URN namespace.

1. 组织稳定性和长期维护组织的能力;如果没有这样的证据,应该清楚的是,如果组织不能再维护URN名称空间,URN名称空间如何保持可行。

2. Competency in URN assignment. This will improve the likelihood of persistence (e.g., to minimize the likelihood of conflicts).

2. 能胜任URN任务。这将提高持久性的可能性(例如,将冲突的可能性降至最低)。

3. Commitment to not reassigning existing URNs and to allowing old URNs to continue to be valid (e.g., if the assignee of a URN is no longer a member or customer of the assigning organization, if various information about the assignee or named entity happens to change, or even if the assignee or the named entity itself is no longer in existence; in all these cases, the URN is still valid).

3. 承诺不重新分配现有骨灰盒并允许旧骨灰盒继续有效(例如,如果URN的受让人不再是转让组织的成员或客户,如果受让人或指定实体的各种信息发生变化,或者即使受让人或指定实体本身不再存在;在所有这些情况下,URN仍然有效)。

A formal URN namespace establishes a particular NID, subject to the following constraints (above and beyond the syntax rules already specified):


1. It MUST NOT be an already-registered NID.

1. 它不能是已注册的NID。

2. It MUST NOT start with "urn-" (which is reserved for informal URN namespaces).

2. 它不能以“urn-”开头(这是为非正式的urn名称空间保留的)。

3. It MUST be more than two characters long, and it MUST NOT start with ALPHA ALPHA "-", i.e., any string consisting of two letters followed by one hyphen; such strings are reserved for potential use as NIDs based on ISO alpha-2 country codes [ISO.3166-1] for eventual national registrations of URN namespaces (however, the definition and scoping of rules for allocation of responsibility for such country-code-based URN namespaces are beyond the scope of this document). As a consequence, it MUST NOT start with the string "xn--" or any other string consisting of two letters followed by two hyphens; such strings are reserved for potential representation of DNS A-labels and similar strings in the future [RFC5890].

3. 长度必须超过两个字符,且不得以ALPHA“-”开头,即任何由两个字母后跟一个连字符组成的字符串;此类字符串保留用作基于ISO alpha-2国家代码[ISO.3166-1]的NID,用于URN名称空间的最终国家注册(但是,此类基于国家代码的URN名称空间的责任分配规则的定义和范围超出了本文件的范围)。因此,它不能以字符串“xn--”或由两个字母后跟两个连字符组成的任何其他字符串开头;此类字符串保留用于将来DNS A标签和类似字符串的潜在表示[RFC5890]。

4. It MUST NOT start with the string "X-" so that it will not be confused with or conflict with any experimental URN namespace previously permitted by [RFC3406].

4. 它不能以字符串“X-”开头,以免与[RFC3406]先前允许的任何实验性URN命名空间相混淆或冲突。

Applicants and reviewers considering new NIDs should also be aware that they may have semantic implications and hence be a source of conflict. Particular attention should be paid to strings that might be construed as identifiers for, or registered under the authority of, countries (including ISO 3166-1 alpha-3 codes) and to strings that might imply association with existing URI schemes, non-URN identifier systems, or trademarks. However, in line with traditional policies, disputes about "ownership" of particular strings are disagreements among the parties involved; neither IANA nor the IETF will become involved in such disputes except in response to orders from a court of competent jurisdiction.

考虑新NID的申请人和审核人还应意识到,它们可能具有语义含义,因此是冲突的根源。应特别注意可能被解释为国家标识符或在国家授权下注册的字符串(包括ISO 3166-1 alpha-3代码),以及可能暗示与现有URI方案、非URN标识符系统或商标关联的字符串。然而,按照传统政策,有关特定字符串“所有权”的争议是有关各方之间的分歧;IANA和IETF都不会卷入此类纠纷,除非是响应具有管辖权的法院的命令。

5.2. Informal URN Namespaces
5.2. 非正式URN名称空间

Informal URN namespaces are full-fledged URN namespaces, with all the associated rights and responsibilities. Informal URN namespaces differ from formal URN namespaces in the process for assigning the NID: for an informal URN namespace, the registrant does not designate the NID; instead, IANA assigns the NID consisting of the string "urn-" followed by one or more digits (e.g., "urn-7") where the


digits consist of the next available number in the sequence of positive integers assigned to informal URN namespaces. Thus, the syntax of an informal URN namespace identifier is:


       InformalNamespaceName = "urn-" Number
       Number                = DigitNonZero 0*Digit
       DigitNonZero          = "1"/ "2" / "3" / "4"/ "5"
                             / "6" / "7" / "8" / "9"
       Digit                 = "0" / DigitNonZero
       InformalNamespaceName = "urn-" Number
       Number                = DigitNonZero 0*Digit
       DigitNonZero          = "1"/ "2" / "3" / "4"/ "5"
                             / "6" / "7" / "8" / "9"
       Digit                 = "0" / DigitNonZero

The only restrictions on <Number> are that it (1) consist strictly of ASCII digits, (2) not have leading zeros, and (3) not cause the NID to exceed the length limitations defined for the URN syntax (see Section 2).


6. Defining and Registering a URN Namespace
6. 定义和注册URN命名空间
6.1. Overview
6.1. 概述

Because the space of URN namespaces is itself managed, the definition of a URN namespace SHOULD pay particular attention to:


1. The purpose of the URN namespace.

1. URN名称空间的用途。

2. The syntax of URNs assigned within the URN namespace, including the internal syntax and anticipated effects of r-components or q-components. (The syntax and interpretation of f-components are defined in RFC 3986.)

2. 在URN名称空间中分配的URN语法,包括内部语法和r组件或q组件的预期效果。(RFC 3986中定义了f组件的语法和解释。)

3. The process for assigning URNs within the URN namespace.

3. 在URN命名空间中分配URN的过程。

4. The security implications of assigning URNs within the URN namespace and of using the assigned URNs.

4. 在URN命名空间内分配URN和使用分配的URN的安全性影响。

5. Any potential interoperability issues with URNs assigned within the URN namespace.

5. 与在URN命名空间内分配的URN存在任何潜在的互操作性问题。

6. Optionally, the process for resolving URNs assigned within the URN namespace.

6. (可选)解析在URN命名空间中分配的URN的过程。

The section on completing the template (Section 6.4) explains these matters in greater detail. Although the registration templates are the same in all cases, slightly different procedures are used depending on the source of the registration.


6.2. Registration Policy and Process: Community Registrations
6.2. 注册政策和流程:社区注册

The basic registration policy for URN namespaces is Expert Review as defined in the IANA Considerations document [RFC5226]. For URN namespaces or their definitions that are intended to become standards or constituent parts of standards, the output of the Expert Review process is intended to be a report rather than instructions to IANA to take action (see below). The key steps are:


1. Fill out the URN namespace registration template (see Section 6.4 and Appendix A). This can be done as part of an Internet-Draft or a specification in another series, although that is not a requirement.

1. 填写URN名称空间注册模板(参见第6.4节和附录A)。这可以作为互联网草案或其他系列规范的一部分来完成,尽管这不是一项要求。

2. Send the completed template to the discussion list for review.

2. 将完成的模板发送到urn@ietf.org供审查的讨论清单。

3. If necessary to address comments received, repeat steps 1 and 2.

3. 如果需要处理收到的评论,请重复步骤1和2。

4. If the Designated Experts approve the request and no standardization action is involved, the IANA will register the requested NID. If standardization is anticipated, the Designated Experts will prepare a report and forward it to the appropriate standards approval body (the IESG in the case of the IETF); IANA will register the requested NID only after receiving directions from that body and a copy of the Expert Review report.

4. 如果指定专家批准了请求,且未涉及任何标准化行动,IANA将注册请求的NID。如果预计标准化,指定专家将编制一份报告,并将其转发给相应的标准批准机构(IETF的IESG);IANA只有在收到该机构的指示和专家评审报告副本后,才会注册所要求的NID。

A URN namespace registration can be revised by updating the registration template, following the same steps outlined above for new registrations. A revised registration MUST describe differences from prior versions and SHOULD make special note of any relevant changes in the underlying technologies or URN namespace management processes.


Experience to date with URN namespace registration requests has shown that registrants sometimes do not initially understand some of the subtleties of URN namespaces and that defining the URN namespace in the form of a specification enables the registrants to clearly formulate their "contract" with the intended user community. Therefore, although the registration policy for formal URN namespaces is Expert Review and a specification (as distinct from the registration template) is not strictly required, registrants SHOULD provide a stable specification documenting the URN namespace definition and expanding upon the issues described herein.


Because naming can be difficult and contentious, URN namespace registrants and the Designated Experts are strongly encouraged to work together in a spirit of good faith and mutual understanding to


achieve rough consensus (see [RFC7282]) on handling registration requests. They are also encouraged to bring additional expertise into the discussion if that would be helpful in providing perspective or otherwise resolving issues.


Especially when iterations in the registration process are prolonged, Designated Experts are expected to take reasonable precautions to avoid "race conditions" on proposed NIDs and, if such situations arise, to encourage applicants to work out any conflicts among themselves.


6.3. Registration Policy and Process: Fast Track for Standards Development Organizations, Scientific Societies, and Similar Bodies

6.3. 注册政策和流程:标准开发组织、科学协会和类似机构的快速通道

The IETF recognizes that situations will arise in which URN namespaces will be created to either embed existing and established standards, particularly identifier standards, or reflect knowledge, terminology, or methods of organizing information that lie well outside the IETF's scope or the likely subject matter knowledge of its Designated Experts. In situations in which the registration request originates from, or is authorized by, a recognized standards development organization, scientific society, or their designees, a somewhat different procedure is available at the option of that body:


1. The URN namespace registration template is filled out and submitted as in steps 1 and 2 of Section 6.2.

1. 按照第6.2节的步骤1和2填写并提交URN命名空间注册模板。

2. A specification is required that reflects or points to the needed external standards or specifications. Publication in the RFC Series or through an IETF process (e.g., posting as an Internet-Draft) is not expected and would be appropriate only under very unusual circumstances.

2. 需要反映或指向所需外部标准或规范的规范。在RFC系列中或通过IETF过程(例如,作为互联网草稿发布)中发布是不可能的,并且只有在非常不寻常的情况下才是合适的。

3. The reviews on the discussion list and by the Designated Experts are strictly advisory, with the decisions about what advice to accept and the length of time to allocate to the process strictly under the control of the external body.

3. 讨论清单上的审查和指定专家的审查都是严格的咨询性审查,关于接受何种咨询意见以及分配给该进程的时间长短的决定严格由外部机构控制。

4. When that body concludes that the application is sufficiently mature, its representative(s) will request that IANA complete the registration for the NID, and IANA will do so.

4. 当该机构认定申请已经足够成熟时,其代表将要求IANA完成NID的注册,IANA将这样做。

Decisions about whether to recognize the requesting entity as a standards development organization or scientific society are the responsibility of the IESG.


A model similar to this has already been defined for recognized standards development organizations that wish to register media types. The document describing that mechanism [RFC6838] provides somewhat more information about the general approach.


6.4. Completing the Template
6.4. 完成模板

A template for defining and registering a URN namespace is provided in Appendix A. This section describes considerations for completing the template.


6.4.1. Purpose
6.4.1. 意图

The "Purpose" section of the template describes matters such as:


1. The kinds of resources identified by URNs assigned within the URN namespace.

1. 由在URN命名空间中分配的URN标识的资源类型。

2. The scope and applicability of the URNs assigned within the URN namespace; this might include information about the community of use (e.g., a particular nation, industry, technology, or organization), whether the assigned URNs will be used on public networks or private networks, etc.

2. 在URN名称空间中分配的URN的范围和适用性;这可能包括有关使用社区(例如,特定国家、行业、技术或组织)的信息,指定的URN是否将用于公共网络或专用网络等。

3. How the intended community (and the Internet community at large) will benefit from using or resolving the assigned URNs.

3. 预期社区(以及整个互联网社区)将如何从使用或解析指定的URN中受益。

4. How the URN namespace relates to and complements existing URN namespaces, URI schemes, and non-URN identifier systems.

4. URN名称空间与现有URN名称空间、URI方案和非URN标识符系统的关联和补充方式。

5. The kinds of software applications that can use or resolve the assigned URNs (e.g., by differentiating among disparate URN namespaces, identifying resources in a persistent fashion, or meaningfully resolving and accessing services associated with the URN namespace).

5. 可以使用或解析分配的URN的软件应用程序的种类(例如,通过区分不同的URN名称空间,以持久方式标识资源,或有意义地解析和访问与URN名称空间关联的服务)。

6. Whether resolution services are available or will be available (and, if so, the nature or identity of the services). Examples of q-component and (when they are standardized) r-component semantics and syntax are helpful here, even if detailed definitions are provided elsewhere or later.

6. 解析服务是否可用或将可用(如果可用,服务的性质或标识)。q-component和(当它们被标准化时)r-component语义和语法的示例在这里很有用,即使在别处或以后提供了详细的定义。

7. Whether the URN namespace or its definition is expected to become a constituent part of a standard being developed in the IETF or some other recognized standards body.

7. URN名称空间或其定义是否有望成为IETF或某些其他公认标准机构正在开发的标准的组成部分。

6.4.2. Syntax
6.4.2. 语法

The "Syntax" section of the template contains:


1. A description of the structure of URNs within the URN namespace, in conformance with the fundamental URN syntax. The structure might be described in terms of a formal definition (e.g., using ABNF [RFC5234]), an algorithm for generating conformant URNs, or a regular expression for parsing the name into constituent parts; alternatively, the structure might be opaque.

1. URN命名空间中URN结构的描述,符合基本URN语法。可以根据形式定义(例如,使用ABNF[RFC5234])、生成一致URN的算法或将名称解析为组成部分的正则表达式来描述该结构;或者,结构可能是不透明的。

2. Any special character encoding rules for assigned URNs (e.g., which character ought to always be used for quotes).

2. 指定URN的任何特殊字符编码规则(例如,应始终使用哪个字符作为引号)。

3. Rules for determining URN-equivalence between two names in the URN namespace. Such rules ought to always have the effect of eliminating false negatives that might otherwise result from comparison. If it is appropriate and helpful, reference can be made to particular equivalence rules defined in the URI specification [RFC3986] or to Section 3 of this document. Examples of URN-equivalence rules include equivalence between uppercase and lowercase characters in the NSS, between hyphenated and non-hyphenated groupings in the name, or between single quotes and double quotes. There may also be namespace-specific special encoding considerations, especially for URNs that contain embedded forms of names from non-URN identifier systems. (Note that these are not normative statements for any kind of best practice related to handling of relationships between characters in general; such statements are limited to one particular URN namespace only.)

3. 用于确定URN命名空间中两个名称之间的URN等效性的规则。这样的规则应该始终具有消除错误否定的效果,否则可能会导致比较。如果适当且有帮助,可以参考URI规范[RFC3986]中定义的特定等价规则或本文档第3节。URN等效规则的示例包括NSS中大小写字符之间的等效、名称中连字符和非连字符分组之间的等效、单引号和双引号之间的等效。还可能存在特定于命名空间的特殊编码注意事项,特别是对于包含非URN标识符系统中名称的嵌入形式的URN。(请注意,这些不是与处理字符之间关系相关的任何类型的最佳实践的规范性声明;此类声明仅限于一个特定的URN命名空间。)

4. Any special considerations necessary for conforming with the URN syntax. This is particularly applicable in the case of existing, non-URN identifier systems that are used in the context of URNs. For example, if a non-URN identifier system is used in contexts other than URNs, it might make use of characters that are reserved in the URN syntax. This section ought to note any such characters and outline necessary mappings to conform to URN syntax. Normally, this will be handled by percent-encoding the character as specified in Section 2.1 of the URI specification [RFC3986] and as discussed in Section 1.2.2 of this specification.

4. 符合URN语法所需的任何特殊注意事项。这尤其适用于在URN上下文中使用的现有非URN标识符系统。例如,如果在非URN的上下文中使用非URN标识符系统,则可能会使用URN语法中保留的字符。本节应注意任何此类字符,并概述符合URN语法的必要映射。通常,这将通过URI规范[RFC3986]第2.1节中规定的字符百分比编码以及本规范第1.2.2节中讨论的字符百分比编码来处理。

5. Any special considerations for the meaning of q-components (e.g., keywords) or f-components (e.g., predefined terms) in the context of this URN namespace.

5. 在此URN名称空间上下文中对q-组件(例如关键字)或f-组件(例如预定义术语)的含义的任何特殊考虑。

6.4.3. Assignment
6.4.3. 分配

The "Assignment" section of the template describes matters such as:


1. Mechanisms or authorities for assigning URNs to resources. It ought to make clear whether assignment is completely open (e.g., following a particular procedure such as first-come, first-served (FCFS)), completely closed (e.g., for a private organization), or limited in various ways (e.g., delegated to authorities recognized by a particular organization); if limited, it ought to explain how to become an assigner of names or how to request assignment of names from existing assignment authorities.

1. 将URN分配给资源的机制或权限。应明确任务是完全开放的(例如,遵循特定程序,如先到先得(FCFS))、完全关闭的(例如,对于私人组织)还是以各种方式受限的(例如,委托给特定组织认可的权限);如有限制,应说明如何成为名称转让人或如何向现有转让当局请求转让名称。

2. Methods for ensuring that URNs within the URN namespace are unique. For example, names might be assigned sequentially or in accordance with some well-defined process by a single authority, assignment might be partitioned among delegated authorities that are individually responsible for respecting uniqueness rules, or URNs might be created independently following an algorithm that itself guarantees uniqueness.

2. 用于确保URN命名空间中的URN唯一的方法。例如,名称可以由单个权限按顺序分配或按照某个定义良好的流程分配,分配可以在单独负责遵守唯一性规则的委托权限之间进行划分,或者可以按照本身保证唯一性的算法独立创建URN。

6.4.4. Security and Privacy
6.4.4. 安全和隐私

The "Security and Privacy" section of the template describes any potential issues related to security and privacy with regard to assignment, use, and resolution of names within the URN namespace. Examples of such issues include:


o The consequences of producing false negatives and false positives during comparison for URN-equivalence (see Section 3.1 of this specification and "Issues in Identifier Comparison for Security Purposes" [RFC6943]).

o 在URN等效性比较期间产生误报和误报的后果(参见本规范第3.1节和“出于安全目的的标识符比较问题”[RFC6943])。

o Leakage of private information when names are communicated on the public Internet.

o 在公共互联网上传播姓名时泄露私人信息。

o The potential for directory harvesting.

o 目录获取的潜力。

o Various issues discussed in the guidelines for security considerations in RFCs [RFC3552] and the privacy considerations for Internet protocols [RFC6973]. In particular, note the privacy considerations text for the Global System for Mobile Communications Association (GSMA) / International Mobile station Equipment Identity (IMEI) namespace [RFC7254], which may provide a useful model for such cases.

o RFCs[RFC3552]安全注意事项指南和互联网协议隐私注意事项[RFC6973]中讨论的各种问题。特别是,请注意全球移动通信系统协会(GSMA)/国际移动站设备标识(IMEI)名称空间[RFC7254]的隐私注意事项文本,该文本可为此类情况提供有用的模型。

6.4.5. Interoperability
6.4.5. 互操作性

The "Interoperability" section MUST specify any known potential issues related to interoperability. Examples include possible confusion with other URN namespaces, non-URN identifier systems, or URI schemes because of syntax (e.g., percent-encoding of certain characters) or scope (e.g., overlapping areas of interest). If at all possible, concerns that arise during the registration of a URN namespace (e.g., due to the syntax or scope of a non-URN identifier system) should be resolved as part of or in parallel to the registration process.


6.4.6. Resolution
6.4.6. 决议

The "Resolution" section MUST specify whether resolution mechanisms are intended or anticipated for URNs assigned within the URN namespace.


If resolution is intended, then this section SHOULD specify whether the organization that assigns URNs within the URN namespace intends to operate or recommend any resolution services for URNs within that URN namespace. In addition, if the assigning organization intends to implement registration for publicly advertised resolution services (for example, using a system developed in the spirit of the original architectural principles and service descriptions for URN resolution [RFC2276] [RFC2483]), then this section SHOULD list or reference the requirements for being publicly advertised by the assigning organization. In addition, this section SHOULD describe any special considerations for the handling of r-components in the context of this URN namespace.


6.4.7. Additional Information
6.4.7. 补充资料

The "Additional Information" section includes information that would be useful to those trying to understand this registration or its relationship to other registrations, such as comparisons to existing URN namespaces that might seem to overlap.


This section of the template is optional.


7. IANA Considerations
7. IANA考虑
7.1. URI Scheme
7.1. URI方案

This section updates the registration of the "urn" URI scheme in the Permanent URI Registry [URI-Registry].


URI Scheme Name: urn


Status: permanent


URI Scheme Syntax: See Section 2 of RFC 8141.

URI方案语法:参见RFC 8141第2节。

URI Scheme Semantics: The "urn" scheme identifies Uniform Resource Names, which are persistent, location-independent resource identifiers.


Encoding Considerations: See Section 2 of RFC 8141.

编码注意事项:参见RFC 8141第2节。

Applications/Protocols That Use This URI Scheme Name: Uniform Resource Names are used in a wide variety of applications, including bibliographic reference systems and as names for Extensible Markup Language (XML) namespaces.


Interoperability Considerations: See Section 4 of RFC 8141.

互操作性注意事项:参见RFC 8141第4节。

Security Considerations: See Sections 6.4.4 and 8 of RFC 8141.

安全注意事项:见RFC 8141第6.4.4节和第8节。

   Contact:  URNBIS working group []
   Contact:  URNBIS working group []

Author/Change Controller: This scheme is registered under the IETF tree. As such, the IETF maintains change control.


References: None.


7.2. Registration of URN Namespaces
7.2. URN名称空间的注册

This document outlines the processes for registering URN namespaces and has implications for the IANA in terms of registries to be maintained (see especially Section 6). In all cases, the IANA ought to assign the appropriate NID (formal or informal) once the procedures outlined in Section 6 have been completed.


7.3. Discussion List for New and Updated NID Registrations
7.3. 新的和更新的NID注册的讨论列表

As discussed elsewhere in this document, the discussion list specified in RFC 3406 ( is discontinued and replaced by the discussion list

如本文件其他部分所述,RFC 3406(urn)中规定的讨论列表已停止并由讨论列表替换

8. Security and Privacy Considerations
8. 安全和隐私注意事项

The definition of a URN namespace needs to account for potential security and privacy issues related to assignment, use, and resolution of names within the URN namespace (e.g., some URN resolvers might assign special meaning to certain characters in the NSS); see Section 6.4.4 for further discussion.


In most cases, URN namespaces provide a way to declare public information. Normally, these declarations will have a relatively low security profile; however, there is always the danger of "spoofing" and providing misinformation. Information in these declarations ought to be taken as advisory.


9. References
9. 工具书类
9.1. Normative References
9.1. 规范性引用文件

[RFC20] Cerf, V., "ASCII format for network interchange", STD 80, RFC 20, DOI 10.17487/RFC0020, October 1969, <>.

[RFC20]Cerf,V.,“网络交换的ASCII格式”,STD 80,RFC 20,DOI 10.17487/RFC0020,1969年10月<>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <>.

[RFC2119]Bradner,S.,“RFC中用于表示需求水平的关键词”,BCP 14,RFC 2119,DOI 10.17487/RFC2119,1997年3月<>.

[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, <>.

[RFC3986]Berners Lee,T.,Fielding,R.,和L.Masinter,“统一资源标识符(URI):通用语法”,STD 66,RFC 3986,DOI 10.17487/RFC3986,2005年1月<>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, DOI 10.17487/RFC5226, May 2008, <>.

[RFC5226]Narten,T.和H.Alvestrand,“在RFCs中编写IANA注意事项部分的指南”,BCP 26,RFC 5226,DOI 10.17487/RFC5226,2008年5月<>.

[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, January 2008, <>.

[RFC5234]Crocker,D.,Ed.和P.Overell,“语法规范的扩充BNF:ABNF”,STD 68,RFC 5234,DOI 10.17487/RFC5234,2008年1月<>.

9.2. Informative References
9.2. 资料性引用

[DOI-URI] Paskin, N., Neylon, E., Hammond, T., and S. Sun, "The "doi" URI Scheme for the Digital Object Identifier (DOI)", Work in Progress, draft-paskin-doi-uri-04, June 2003.


[IANA-URN] Saint-Andre, P. and M. Cotton, "A Uniform Resource Name (URN) Namespace for IANA Registries", Work in Progress, draft-saintandre-iana-urn-01, February 2013.

[IANA-URN]Saint Andre,P.和M.Cotton,“IANA注册表的统一资源名(URN)命名空间”,正在进行的工作,草稿-Saint Andre-IANA-URN-01,2013年2月。

[ISO.27729.2012] ISO, "Information and documentation - International standard name identifier (ISNI)", ISO 27729:2012, Technical Committee ISO/TC 46, Information and documentation, Subcommittee SC 9, Identification and description, March 2012.

[ISO.27729.2012]ISO,“信息和文件-国际标准名称标识符(ISNI)”,ISO 27729:2012,技术委员会ISO/TC 46,信息和文件,小组委员会SC 9,标识和说明,2012年3月。

[ISO.3166-1] ISO, "Codes for the representation of names of countries and their subdivisions -- Part 1: Country codes", ISO 3166-1:2013, November 2013.

[ISO.3166-1]ISO,“国家及其分支机构名称表示代码——第1部分:国家代码”,ISO 3166-1:2013,2013年11月。

[RFC1737] Sollins, K. and L. Masinter, "Functional Requirements for Uniform Resource Names", RFC 1737, DOI 10.17487/RFC1737, December 1994, <>.

[RFC1737]Sollins,K.和L.Masinter,“统一资源名称的功能要求”,RFC 1737,DOI 10.17487/RFC1737,1994年12月<>.

[RFC1738] Berners-Lee, T., Masinter, L., and M. McCahill, "Uniform Resource Locators (URL)", RFC 1738, DOI 10.17487/RFC1738, December 1994, <>.

[RFC1738]Berners Lee,T.,Masinter,L.,和M.McCahill,“统一资源定位器(URL)”,RFC 1738,DOI 10.17487/RFC1738,1994年12月<>.

[RFC1808] Fielding, R., "Relative Uniform Resource Locators", RFC 1808, DOI 10.17487/RFC1808, June 1995, <>.

[RFC1808]菲尔丁,R.,“相对统一资源定位器”,RFC 1808,DOI 10.17487/RFC1808,1995年6月<>.

[RFC2141] Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141, May 1997, <>.

[RFC2141]护城河,R.,“瓮语法”,RFC 2141,DOI 10.17487/RFC2141,1997年5月<>.

[RFC2276] Sollins, K., "Architectural Principles of Uniform Resource Name Resolution", RFC 2276, DOI 10.17487/RFC2276, January 1998, <>.

[RFC2276]Sollins,K.,“统一资源名称解析的架构原则”,RFC 2276,DOI 10.17487/RFC2276,1998年1月<>.

[RFC2483] Mealling, M. and R. Daniel, "URI Resolution Services Necessary for URN Resolution", RFC 2483, DOI 10.17487/RFC2483, January 1999, <>.

[RFC2483]Mealling,M.和R.Daniel,“URN解析所需的URI解析服务”,RFC 2483,DOI 10.17487/RFC2483,1999年1月<>.

[RFC2648] Moats, R., "A URN Namespace for IETF Documents", RFC 2648, DOI 10.17487/RFC2648, August 1999, <>.

[RFC2648]Moats,R.,“IETF文档的URN名称空间”,RFC 2648,DOI 10.17487/RFC2648,1999年8月<>.

[RFC3044] Rozenfeld, S., "Using The ISSN (International Serial Standard Number) as URN (Uniform Resource Names) within an ISSN-URN Namespace", RFC 3044, DOI 10.17487/RFC3044, January 2001, <>.

[RFC3044]Rozenfeld,S.,“在ISSN-URN名称空间中将ISSN(国际序列号)用作URN(统一资源名称)”,RFC 3044,DOI 10.17487/RFC30442001年1月<>.

[RFC3187] Hakala, J. and H. Walravens, "Using International Standard Book Numbers as Uniform Resource Names", RFC 3187, DOI 10.17487/RFC3187, October 2001, <>.

[RFC3187]Hakala,J.和H.Walravens,“使用国际标准书号作为统一资源名称”,RFC 3187,DOI 10.17487/RFC3187,2001年10月<>.

[RFC3188] Hakala, J., "Using National Bibliography Numbers as Uniform Resource Names", RFC 3188, DOI 10.17487/RFC3188, October 2001, <>.

[RFC3188]Hakala,J.,“使用国家书目编号作为统一资源名称”,RFC 3188,DOI 10.17487/RFC3188,2001年10月<>.

[RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom, "Uniform Resource Names (URN) Namespace Definition Mechanisms", BCP 66, RFC 3406, DOI 10.17487/RFC3406, October 2002, <>.

[RFC3406]Daigle,L.,van Gulik,D.,Iannella,R.,和P.Faltstrom,“统一资源名称(URN)命名空间定义机制”,BCP 66,RFC 3406,DOI 10.17487/RFC3406,2002年10月<>.

[RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, DOI 10.17487/RFC3552, July 2003, <>.

[RFC3552]Rescorla,E.和B.Korver,“关于安全考虑的RFC文本编写指南”,BCP 72,RFC 3552,DOI 10.17487/RFC3552,2003年7月<>.

[RFC4854] Saint-Andre, P., "A Uniform Resource Name (URN) Namespace for Extensions to the Extensible Messaging and Presence Protocol (XMPP)", RFC 4854, DOI 10.17487/RFC4854, April 2007, <>.

[RFC4854]Saint Andre,P.,“扩展消息和状态协议(XMPP)扩展的统一资源名(URN)命名空间”,RFC 4854,DOI 10.17487/RFC4854,2007年4月<>.

[RFC5122] Saint-Andre, P., "Internationalized Resource Identifiers (IRIs) and Uniform Resource Identifiers (URIs) for the Extensible Messaging and Presence Protocol (XMPP)", RFC 5122, DOI 10.17487/RFC5122, February 2008, <>.

[RFC5122]Saint Andre,P.,“可扩展消息和状态协议(XMPP)的国际化资源标识符(IRI)和统一资源标识符(URI)”,RFC 5122,DOI 10.17487/RFC5122,2008年2月<>.

[RFC5890] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, DOI 10.17487/RFC5890, August 2010, <>.

[RFC5890]Klensin,J.,“应用程序的国际化域名(IDNA):定义和文档框架”,RFC 5890,DOI 10.17487/RFC5890,2010年8月<>.

[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence Protocol (XMPP): Core", RFC 6120, DOI 10.17487/RFC6120, March 2011, <>.

[RFC6120]Saint Andre,P.,“可扩展消息和状态协议(XMPP):核心”,RFC 6120,DOI 10.17487/RFC6120,2011年3月<>.

[RFC6288] Reed, C., "URN Namespace for the Defence Geospatial Information Working Group (DGIWG)", RFC 6288, DOI 10.17487/RFC6288, August 2011, <>.

[RFC6288]Reed,C.“国防地理空间信息工作组(DGIWG)的URN名称空间”,RFC 6288,DOI 10.17487/RFC6288,2011年8月<>.

[RFC6648] Saint-Andre, P., Crocker, D., and M. Nottingham, "Deprecating the "X-" Prefix and Similar Constructs in Application Protocols", BCP 178, RFC 6648, DOI 10.17487/RFC6648, June 2012, <>.

[RFC6648]圣安德烈,P.,克罗克,D.,和M.诺丁汉,“反对应用协议中的“X-”前缀和类似结构”,BCP 178,RFC 6648,DOI 10.17487/RFC6648,2012年6月<>.

[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type Specifications and Registration Procedures", BCP 13, RFC 6838, DOI 10.17487/RFC6838, January 2013, <>.

[RFC6838]Freed,N.,Klensin,J.和T.Hansen,“介质类型规范和注册程序”,BCP 13,RFC 6838,DOI 10.17487/RFC6838,2013年1月<>.

[RFC6943] Thaler, D., Ed., "Issues in Identifier Comparison for Security Purposes", RFC 6943, DOI 10.17487/RFC6943, May 2013, <>.

[RFC6943]Thaler,D.,Ed.,“出于安全目的的标识符比较问题”,RFC 6943,DOI 10.17487/RFC6943,2013年5月<>.

[RFC6963] Saint-Andre, P., "A Uniform Resource Name (URN) Namespace for Examples", BCP 183, RFC 6963, DOI 10.17487/RFC6963, May 2013, <>.

[RFC6963]Saint Andre,P.,“一个统一资源名(URN)名称空间示例”,BCP 183,RFC 6963,DOI 10.17487/RFC6963,2013年5月<>.

[RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., Morris, J., Hansen, M., and R. Smith, "Privacy Considerations for Internet Protocols", RFC 6973, DOI 10.17487/RFC6973, July 2013, <>.

[RFC6973]Cooper,A.,Tschofenig,H.,Aboba,B.,Peterson,J.,Morris,J.,Hansen,M.,和R.Smith,“互联网协议的隐私考虑”,RFC 6973,DOI 10.17487/RFC6973,2013年7月<>.

[RFC7254] Montemurro, M., Ed., Allen, A., McDonald, D., and P. Gosden, "A Uniform Resource Name Namespace for the Global System for Mobile Communications Association (GSMA) and the International Mobile station Equipment Identity (IMEI)", RFC 7254, DOI 10.17487/RFC7254, May 2014, <>.

[RFC7254]Montemurro,M.,Ed.,Allen,A.,McDonald,D.,和P.Gosden,“全球移动通信系统协会(GSMA)和国际移动站设备标识(IMEI)的统一资源名称空间”,RFC 7254,DOI 10.17487/RFC7254,2014年5月<>.

[RFC7282] Resnick, P., "On Consensus and Humming in the IETF", RFC 7282, DOI 10.17487/RFC7282, June 2014, <>.

[RFC7282]Resnick,P.,“关于IETF中的共识和嗡嗡声”,RFC 7282,DOI 10.17487/RFC7282,2014年6月<>.

[RFC7320] Nottingham, M., "URI Design and Ownership", BCP 190, RFC 7320, DOI 10.17487/RFC7320, July 2014, <>.

[RFC7320]诺丁汉,M.,“URI设计和所有权”,BCP 190,RFC 7320,DOI 10.17487/RFC7320,2014年7月<>.

[RFC7462] Liess, L., Ed., Jesske, R., Johnston, A., Worley, D., and P. Kyzivat, "URNs for the Alert-Info Header Field of the Session Initiation Protocol (SIP)", RFC 7462, DOI 10.17487/RFC7462, March 2015, <>.

[RFC7462]Liess,L.,Ed.,Jeske,R.,Johnston,A.,Worley,D.,和P.Kyzivat,“会话启动协议(SIP)警报信息头字段的URN”,RFC 7462,DOI 10.17487/RFC7462,2015年3月<>.

[RFC7613] Saint-Andre, P. and A. Melnikov, "Preparation, Enforcement, and Comparison of Internationalized Strings Representing Usernames and Passwords", RFC 7613, DOI 10.17487/RFC7613, August 2015, <>.

[RFC7613]Saint Andre,P.和A.Melnikov,“代表用户名和密码的国际化字符串的准备、实施和比较”,RFC 7613,DOI 10.17487/RFC7613,2015年8月<>.

[UAX31] The Unicode Consortium, "Unicode Standard Annex #31: Unicode Identifier and Pattern Syntax", Unicode 9.0.0, June 2015, <>.

[UAX31]Unicode联合会,“Unicode标准附件#31:Unicode标识符和模式语法”,Unicode 9.0.0,2015年6月<>.

[UNICODE] The Unicode Consortium, "The Unicode Standard", <>.


[URI-Registry] IANA, "Uniform Resource Identifier (URI) Schemes", <>.


[XML-BASE] Marsh, J. and R. Tobin, "XML Base (Second Edition)", W3C Recommendation REC-xmlbase-20090128, January 2009, <>.


[XML-NAMES] Thompson, H., Hollander, D., Layman, A., Bray, T., and R. Tobin, "Namespaces in XML 1.0 (Third Edition)", W3C Recommendation REC-xml-names-20091208, December 2009, <>.

[XML-NAMES]Thompson,H.,Hollander,D.,Layman,A.,Bray,T.,和R.Tobin,“XML 1.0中的名称空间(第三版)”,W3C建议REC-XML-NAMES-20091208,2009年12月<>.

Appendix A. Registration Template

Namespace Identifier: Requested of IANA (formal) or assigned by IANA (informal).


Version: The version of the registration, starting with 1 and incrementing by 1 with each new version.


Date: The date when the registration is requested of IANA, using the format YYYY-MM-DD.


Registrant: The person or organization that has registered the NID, including the name and address of the registering organization, as well as the name and contact information (email, phone number, or postal address) of the designated contact person. If the registrant is a recognized standards development organization, scientific society, or similar body requesting the fast-track registration procedure (see Section 6.3), that information should be clearly indicated in this section of the template.


Purpose: Described in Section 6.4.1 of this document.


Syntax: Described in Section 6.4.2 of this document. Unless the registration explicitly describes the semantics of r-components, q-components, and f-components in the context of this URN namespace, those semantics are undefined.


Assignment: Described in Section 6.4.3 of this document.


Security and Privacy: Described in Section 6.4.4 of this document.


Interoperability: Described in Section 6.4.5 of this document.


Resolution: Described in Section 6.4.6 of this document.


Documentation: A pointer to an RFC, a specification published by another standards development organization, or another stable document that provides further information about this URN namespace.


Additional Information: Described in Section 6.4.7 of this document.


Revision Information: Description of changes from prior version(s). (Applicable only when earlier registrations have been revised.)


Appendix B. Changes from RFC 2141
附录B.RFC 2141的变更

This document makes substantive changes from the syntax and semantics of [RFC2141]:


B.1. Syntax Changes from RFC 2141
B.1. RFC 2141的语法更改

The syntax of URNs as provided in [RFC2141] was defined before the updated specification of URIs in [RFC3986]. The definition of URN syntax is updated in this document to do the following:


o Ensure consistency with the URI syntax.

o 确保与URI语法一致。

o Facilitate the use of URNs with parameters similar to URI queries and fragments.

o 方便使用参数类似于URI查询和片段的URN。

o Permit parameters influencing URN resolution.

o 允许影响URN分辨率的参数。

o Ease the use of URNs with non-URN identifier systems that include the "/" character.

o 易于将URN与包含“/”字符的非URN标识符系统一起使用。

In particular, this specification does the following:


o Extends URN syntax to explicitly allow the characters "/", "?", and "#", which were reserved for future use by RFC 2141. This change also effectively allows several components of the URI syntax although without necessarily tying those components to URI semantics.

o 扩展URN语法以显式允许字符“/”、“?”和“#”,这些字符是RFC 2141保留供将来使用的。此更改还有效地允许URI语法的多个组件,尽管不必将这些组件绑定到URI语义。

o Defines general syntax for an additional component that can be used in interactions with a URN resolution service.

o 定义可用于与URN解析服务交互的其他组件的通用语法。

o Disallows "-" at the end of the NID.

o 不允许在NID末尾使用“-”。

o Allows the "/", "~", and "&" characters in the NSS.

o 允许在NSS中使用“/”、“~”和“&”字符。

o Makes several smaller syntax adjustments.

o 进行一些较小的语法调整。

B.2. Other Changes from RFC 2141
B.2. RFC 2141的其他变更

o Formally registers "urn" as a URI scheme.

o 将“urn”正式注册为URI方案。

o Allows what are now called r-components, q-components, and f-components.

o 允许现在称之为r分量、q分量和f分量。

In addition, some of the text has been updated to be consistent with the definition of URIs [RFC3986] and the processes for registering information with the IANA [RFC5226], as well as more modern guidance with regard to security [RFC3552], privacy [RFC6973], and identifier comparison [RFC6943].


Appendix C. Changes from RFC 3406
附录C.RFC 3406的变更

This document makes the following substantive changes from [RFC3406]:


1. Relaxes the registration policy for formal URN namespaces from "IETF Review" to "Expert Review" as discussed in Section 6.2.

1. 将正式URN名称空间的注册策略从“IETF审查”放宽为“专家审查”,如第6.2节所述。

2. Removes the category of experimental URN namespaces, consistent with [RFC6648]. Experimental URN namespaces were denoted by prefixing the namespace identifier with the string "X-". Because experimental URN namespaces were never registered, removing the experimental category has no impact on the existing registries. Because experimental URN namespaces are not managed, strings conforming to URN syntax within experimental URN namespaces are not valid URNs. Truly experimental usages may, of course, employ the "example" namespace [RFC6963].

2. 删除实验性URN名称空间的类别,与[RFC6648]一致。实验URN名称空间是通过在名称空间标识符前面加上字符串“X-”来表示的。由于实验性URN名称空间从未注册,因此删除实验性类别对现有注册表没有影响。由于实验性URN命名空间不受管理,因此符合实验性URN命名空间中URN语法的字符串不是有效的URN。当然,真正的实验性用法可能使用“示例”名称空间[RFC6963]。

3. Adds some information to, but generally simplifies, the URN namespace registration template.

3. 向URN命名空间注册模板添加一些信息,但通常会简化这些信息。



Many thanks to Marc Blanchet, Leslie Daigle, Martin Duerst, Juha Hakala, Ted Hardie, Alfred Hoenes, Paul Jones, Barry Leiba, Sean Leonard, Larry Masinter, Keith Moore, Mark Nottingham, Julian Reschke, Lars Svensson, Henry S. Thompson, Dale Worley, and other participants in the URNBIS working group for their input. Alfred Hoenes in particular edited an earlier draft version of this document and served as co-chair of the URNBIS working group.

非常感谢马克·布兰切特、莱斯利·戴格尔、马丁·杜尔斯、朱哈·哈卡拉、特德·哈迪、阿尔弗雷德·霍恩斯、保罗·琼斯、巴里·莱巴、肖恩·伦纳德、拉里·马斯特、基思·摩尔、马克·诺丁汉、朱利安·雷什克、拉尔斯·斯文森、亨利·S·汤普森、戴尔·沃利以及民革联工作组的其他参与者的投入。阿尔弗雷德·霍恩斯(Alfred Hoenes)特别编辑了本文件的早期草案,并担任了URNBIS工作组的联合主席。

Juha Hakala deserves special recognition for his dedication to successfully completing this work, as do Andrew Newton and Melinda Shore in their roles as working group co-chairs and Barry Leiba in his role as area director and then as co-chair.

朱哈·哈卡拉(Juha Hakala)对成功完成这项工作的贡献值得特别表彰,安德鲁·牛顿(Andrew Newton)和梅琳达·肖尔(Melinda Shore)担任工作组联席主席,巴里·莱巴(Barry Leiba)担任区域总监,然后担任联席主席。



RFC 2141, which provided the basis for the syntax portion of this document, was authored by Ryan Moats.

RFC 2141是Ryan Moats编写的,它为本文档的语法部分提供了基础。

RFC 3406, which provided the basis for the namespace portion of this document, was authored by Leslie Daigle, Dirk-Willem van Gulik, Renato Iannella, and Patrik Faltstrom.

RFC 3406是Leslie Daigle、Dirk Willem van Gulik、Renato Iannella和Patrik Faltstrom编写的,它为本文档的名称空间部分提供了基础。

Their work is gratefully acknowledged.


Authors' Addresses


Peter Saint-Andre Filament P.O. Box 787 Parker, CO 80134 United States of America


   Phone: +1 720 256 6756
   URI:   <>
   Phone: +1 720 256 6756
   URI:   <>

John C. Klensin 1770 Massachusetts Ave, Ste 322 Cambridge, MA 02140 United States of America


   Phone: +1 617 245 1457
   Phone: +1 617 245 1457