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authorThomas Voss <mail@thomasvoss.com> 2024-11-27 20:54:24 +0100
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+Internet Engineering Task Force (IETF) J. Hakala
+Request for Comments: 8458 The National Library of Finland
+Obsoletes: 3188 October 2018
+Category: Informational
+ISSN: 2070-1721
+
+
+ Using National Bibliography Numbers as Uniform Resource Names
+
+Abstract
+
+ National Bibliography Numbers (NBNs) are used by national libraries
+ and other organizations in order to identify resources in their
+ collections. NBNs are usually applied to resources that are not
+ catered for by established (standard) identifier systems such as
+ International Standard Book Number (ISBN).
+
+ A Uniform Resource Name (URN) namespace for NBNs was established in
+ 2001 in RFC 3188. Since then, a number of European national
+ libraries have implemented URN:NBN-based systems.
+
+ This document replaces RFC 3188 and defines how NBNs can be supported
+ within the updated URN framework. A revised namespace registration
+ (version 4) compliant to RFC 8141 is included.
+
+Status of This Memo
+
+ This document is not an Internet Standards Track specification; it is
+ published for informational purposes.
+
+ 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). Not all documents
+ approved by the IESG are candidates for any level of Internet
+ Standard; see Section 2 of RFC 7841.
+
+ Information about the current status of this document, any errata,
+ and how to provide feedback on it may be obtained at
+ https://www.rfc-editor.org/info/rfc8458.
+
+
+
+
+
+
+
+
+
+
+
+Hakala Informational [Page 1]
+
+RFC 8458 NBN URNs October 2018
+
+
+Copyright Notice
+
+ Copyright (c) 2018 IETF Trust and the persons identified as the
+ document authors. All rights reserved.
+
+ This document is subject to BCP 78 and the IETF Trust's Legal
+ Provisions Relating to IETF Documents
+
+ (https://trustee.ietf.org/license-info) 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.
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2. Conventions Used in This Document . . . . . . . . . . . . . . 5
+ 3. Fundamental Namespace and Community Considerations for NBN . 5
+ 3.1. The URN:NBN Namespace . . . . . . . . . . . . . . . . . . 5
+ 3.2. Community Considerations for NBNs . . . . . . . . . . . . 6
+ 4. National Bibliography Number URNs . . . . . . . . . . . . . . 7
+ 4.1. Assignment . . . . . . . . . . . . . . . . . . . . . . . 7
+ 4.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8
+ 4.2.1. Usage of r-component and q-component . . . . . . . . 10
+ 4.2.2. Usage of f-component . . . . . . . . . . . . . . . . 10
+ 4.3. Encoding Considerations and Lexical Equivalence . . . . . 10
+ 4.4. Resolution and Persistence of NBN-based URNs . . . . . . 12
+ 4.5. Additional Considerations . . . . . . . . . . . . . . . . 13
+ 5. URN Namespace ID (NID) Registration for the National
+ Bibliography Number (NBN) . . . . . . . . . . . . . . . . . . 13
+ 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
+ 7. Security Considerations . . . . . . . . . . . . . . . . . . . 15
+ 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
+ 8.1. Normative References . . . . . . . . . . . . . . . . . . 15
+ 8.2. Informative References . . . . . . . . . . . . . . . . . 16
+ Appendix A. Significant Changes from RFC 3188 . . . . . . . . . 18
+ Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 18
+ Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 18
+ Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 18
+
+
+
+
+
+
+
+
+
+Hakala Informational [Page 2]
+
+RFC 8458 NBN URNs October 2018
+
+
+1. Introduction
+
+ One of the basic permanent Uniform Resource Identifier (URI) schemes
+ (cf. [RFC3986] and [IANA-URI]) is Uniform Resource Name (URN). URNs
+ were originally defined in RFC 2141 [RFC2141]. In 2017, a revision
+ was adopted with new definitions and registration procedures
+ [RFC8141]. Any traditional identifier, when used within the URN
+ system, must have a namespace of its own that is registered with IANA
+ [IANA-URN]. National Bibliography Number (NBN) is one such
+ namespace, specified in 2001 in RFC 3188 [RFC3188].
+
+ This document describes the syntax and usage of NBN URNs and updates
+ the registration of the associated URN namespace. This document
+ additionally describes certain policy assumptions about how national
+ libraries and their partner organizations partition, delegate, and
+ manage the namespace. Violation of those assumptions could impact
+ the utility of the NBN URN namespace.
+
+ URN:NBNs are in production use in several European countries
+ including (in alphabetical order) Austria, Finland, Germany, Hungary,
+ Italy, the Netherlands, Norway, Sweden, and Switzerland. The URN:NBN
+ namespace is collectively managed by these national libraries. URN:
+ NBNs have been applied to diverse content including Web archives,
+ digitized materials, research data, and doctoral dissertations. They
+ can be used by national libraries and organizations cooperating with
+ them.
+
+ As a part of the initial development of the URN system in the late
+ 1990s, the IETF URN Working Group agreed that it was important to
+ demonstrate that the URN syntax can accommodate existing identifier
+ systems. RFC 2288 [RFC2288] investigated the feasibility of using
+ ISBN, ISSN, and SICI (Serial Item and Contribution Identifier) as
+ URNs, with positive results; however, it did not formally register
+ corresponding URN namespaces. (For further discussion of how these
+ systems have evolved as URNs, see RFC 8254 [RFC8254].) This was in
+ part due to the still-evolving process to formalize criteria for
+ namespace definition documents and registration. The criteria were
+ consolidated later in the IETF, first in RFC 2611 [RFC2611], then RFC
+ 3406 [RFC3406], and now RFC 8141 [RFC8141].
+
+ URN namespaces have been registered for NBN, ISBN, and ISSN in RFCs
+ 3188 [RFC3188], 3187 [RFC3187], and 3044 [RFC3044], respectively.
+ ISBN and ISSN namespaces were made compliant with RFC 8141 [RFC8141]
+ in 2017 by publishing revised ISSN [ISSN-namespace] and ISBN
+ [ISBN-namespace] namespace registrations.
+
+
+
+
+
+
+Hakala Informational [Page 3]
+
+RFC 8458 NBN URNs October 2018
+
+
+ The term "National Bibliography Number" encompasses persistent local
+ identifier systems that national libraries and their partner
+ organizations use in addition to the more formally (and
+ internationally) established identifiers. These partner
+ organizations include universities and their libraries and other
+ subsidiaries, other research institutions, plus governmental and
+ public organizations. Some national libraries maintain a significant
+ number of these liaison relationships; for instance, the German
+ National Library had almost 400 by early 2018 [NBN-Resolving].
+
+ In practice, NBN differs from standard identifier systems such as
+ ISBN and ISSN because it is not a single identifier system with
+ standard-specified scope and syntax. Each NBN implementer creates
+ its own system with its own syntax and assignment rules. Each user
+ organization is also obliged to keep track of how NBNs are being
+ used; however, within the generic framework set in this document,
+ local NBN assignment policies may vary considerably.
+
+ Historically, NBNs have been applied in the national bibliographies
+ to identify the resources catalogued into them. Prior to the
+ emergence of bibliographic standard identifiers in the early 1970s,
+ national libraries assigned NBNs to all catalogued publications.
+
+ Since the late 1990s, the NBN scope has been extended to cover a vast
+ range of resources, both originally digital and digitized. Only a
+ small subset of these resources is catalogued in the national
+ bibliographies or other bibliographic databases. Digitized resources
+ and their component parts (such as still images in books or journal
+ articles) are examples of resources that may get NBNs.
+
+ It is possible to extend the scope of the NBN much further. The
+ National Library of Finland is using them in the Finnish National
+ Ontology Service Finto to identify corporate names (see
+ <http://finto.fi/cn/en/>). Using NBNs to identify metadata elements
+ provides a stable basis for creation of linked data.
+
+ Simple guidelines for using NBNs as URNs and the original namespace
+ registration were published in RFC 3188 [RFC3188]. The RFC at hand
+ replaces RFC 3188; sections discussing the methods by which URN:NBNs
+ should be resolved have been updated, unused features have been
+ eliminated, and the text is compliant with the stipulations of the
+ revised URN specification [RFC8141].
+
+
+
+
+
+
+
+
+
+Hakala Informational [Page 4]
+
+RFC 8458 NBN URNs October 2018
+
+
+2. Conventions Used in This Document
+
+ "NBN" refers to any National Bibliography Number identifier system
+ used by the national libraries (or equivalent organizations) and
+ other institutions, which use these identifiers with national
+ libraries' support and permission.
+
+ In this memo, "URN:NBN" is used as a shorthand for "NBN-based URN".
+
+ 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
+ BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
+ capitals, as shown here.
+
+3. Fundamental Namespace and Community Considerations for NBN
+
+3.1. The URN:NBN Namespace
+
+ NBNs are widely used to identify both hand-held and digital resources
+ in the collections of national libraries and other institutions that
+ are responsible for preserving the cultural heritage of their
+ constituents. Resources in these collections are usually preserved
+ for a long time (i.e., for centuries). While the preferred methods
+ for digital preservation may vary over time and depend on the
+ content, the favorite one has been migration. Whenever necessary, a
+ resource in an outdated file format is migrated into a more modern
+ file format. To the extent possible, all old versions of the
+ resource are also kept in order to alleviate the negative effects of
+ partially successful migrations and the gradual loss of original look
+ and feel that may accompany even fully successful migrations. When
+ NBN is used to identify manifestations and there are many of them for
+ a single work, local policy can require that each manifestation ought
+ to have its own NBN.
+
+ NBNs are typically used to identify objects for which standard
+ identifiers such as ISBN are not applicable. However, NBNs can be
+ used for component resources even when the resource as a whole
+ qualifies for a standard identifier. For instance, if a digitized
+ book has an ISBN, JPEG image files of its pages might be assigned
+ NBNs. These URN:NBNs can be used as persistent links to the pages.
+
+ The scope of standard identifier systems such as ISBN and ISSN is
+ limited; they are applicable only to certain kinds of resources. One
+ of the roles of the NBN is to fill in the gaps left by the standard
+ identifiers. Collectively, these identifiers and NBNs cover all
+ resources that national libraries and their partners need to include
+ in their collections.
+
+
+
+Hakala Informational [Page 5]
+
+RFC 8458 NBN URNs October 2018
+
+
+ Section 4 below, and particularly Section 4.1, present a more
+ detailed overview of the structure of the NBN namespace, related
+ institutions, and the identifier assignment principles used.
+
+3.2. Community Considerations for NBNs
+
+ National libraries are the key organizations providing persistent URN
+ resolution services for resources identified with NBNs, independent
+ of their form. As coordinators of NBN usage, national libraries have
+ allowed other organizations, such as university libraries or
+ governmental organizations, to assign NBNs to the resources these
+ organizations preserve for the long term. In such case, the national
+ library coordinates the use of NBNs at the national level. National
+ libraries can also provide URN resolution services and technical
+ services to other NBN users. These organizations are expected to
+ either establish their own URN resolution services or use the
+ technical infrastructure provided by the national library. URN:NBNs
+ are expected to be resolvable and support one or more resolution
+ services.
+
+ Although NBNs can be used to identify component resources, the NBN
+ namespace does not specify a generic, intrinsic syntax for doing
+ that. However, there are at least two different ways in which
+ component resources can be taken into account within the NBN
+ namespace.
+
+ The simplest and probably the most common approach is to assign a
+ separate NBN for each component resource, such as a file containing a
+ digitized page of a book, and make no provisions to make such NBNs
+ discernible in a systematic way from others.
+
+ Second, if the stipulations of the URI generic syntax [RFC3986] and
+ the Internet media type specification [RFC2046] are met, in
+ accordance with the provisions in RFC 8141 [RFC8141], the URN
+ f-component can be attached to URN:NBNs in order to indicate the
+ desired location within the resource supplied by URN resolution.
+
+ From the library community point of view, it is important that the
+ f-component is not a part of the Namespace-Specific String (NSS), and
+ therefore f-component attachment does not mean that the relevant
+ component part is identified. Moreover, the resolution process still
+ retrieves the entire resource even if there is an f-component. The
+ component part selection is applied by the resolution client (e.g.,
+ browser) to the resource returned by the resolution process. In
+ other words, in this latter case the component parts are just logical
+ and physical parts of the identified resource whereas in the former
+ cases they are independently named entities.
+
+
+
+
+Hakala Informational [Page 6]
+
+RFC 8458 NBN URNs October 2018
+
+
+ Resources identified by NBNs are not always available in the
+ Internet. If one is not, the URN:NBN can resolve to a surrogate such
+ as a metadata record describing the identified resource.
+
+ Section 4 below, and particularly Section 4.4, presents a detailed
+ overview of the application of the URN:NBN namespace as well as the
+ principles of, and systems used for, the resolution of NBN-based
+ URNs.
+
+4. National Bibliography Number URNs
+
+4.1. Assignment
+
+ National Bibliography Number (NBN) is a generic term referring to a
+ group of identifier systems administered by national libraries and
+ institutions authorized by them. The NBN assignment is typically
+ performed by the organization hosting the resource. National
+ libraries are committed to permanent preservation of their deposit
+ collections.
+
+ Assignment of NBN-based URNs is controlled on a national level by the
+ national library (or national libraries, if there is more than one).
+ National guidelines can differ, but the identified resources
+ themselves are usually persistent.
+
+ Different national URN:NBN assignment policies have resulted in
+ varying levels of control of the assignment process. Manual URN:NBN
+ assignment by the library personnel provides the tightest control,
+ especially if the URN:NBNs cover only resources catalogued into the
+ national bibliography. In most national libraries, the scope of
+ URN:NBN is already much broader than this. Usage rules can vary
+ within one country, from one URN:NBN sub-namespace to the next.
+
+ Each national library uses NBNs independently of other national
+ libraries; apart from this document, there are no guidelines that
+ specify or control NBN usage. As such, NBNs are unique only on the
+ national level. When used as URNs, base NBN strings MUST be
+ augmented with a controlled prefix, which is the particular nation's
+ ISO 3166-1 alpha-2 two-letter country code (referred to as "ISO
+ country code" below) [ISO3166-1]. These prefixes guarantee
+ uniqueness of the URN:NBNs at the global scale [ISO3166MA].
+
+ National libraries using URN:NBNs usually specify local assignment
+ policies for themselves. Such policy can limit the URN:NBN usage to,
+ e.g., the resources stored in the national library's digital
+ collections or databases. Although this specification does not
+
+
+
+
+
+Hakala Informational [Page 7]
+
+RFC 8458 NBN URNs October 2018
+
+
+ specify principles for URN:NBN assignment policies that can be
+ applied, NBNs assigned to short-lived resources should not be made
+ URN:NBNs unless such policy can be justified.
+
+ URN:NBN assignment policy can clarify, for instance, the local policy
+ concerning identifier assignment to component parts of resources and
+ can specify, with sufficient detail, the syntax of local component
+ identifiers (if there is one as a discernible part of the NBNs). The
+ policy can also cover any employed extensions to the default NBN
+ scope.
+
+ NBNs as such are locally but not globally unique; two national
+ libraries can assign the same NBN to different resources. A prefix,
+ based on the ISO country code as described above, guarantees the
+ global uniqueness of URN:NBNs. Once an NBN has been assigned to a
+ resource, it MUST be persistent, and therefore URN:NBNs are
+ persistent as well.
+
+ A URN:NBN, once it has been generated from a NBN, MUST NOT be reused
+ for another resource.
+
+ Users of the URN:NBN namespace MUST ensure that they do not assign
+ the same URN:NBN twice. Different policies can be applied to
+ guarantee this. For instance, NBNs and corresponding URN:NBNs can be
+ assigned sequentially by programs in order to avoid human mistakes.
+ It is also possible to use printable representations of checksums
+ such as SHA-1 [RFC6234] as NBNs.
+
+4.2. Syntax
+
+ The Namespace-Specific String (NSS) will consist of three parts:
+
+ o a prefix consisting of an ISO 3166-1 alpha-2 country code and
+ optional sub-namespace code(s) separated by a colon(s);
+
+ o a hyphen (-) as the delimiting character; and,
+
+ o an NBN string assigned by the national library or sub-delegated
+ authority.
+
+
+
+
+
+
+
+
+
+
+
+
+Hakala Informational [Page 8]
+
+RFC 8458 NBN URNs October 2018
+
+
+ The following formal definition uses ABNF [RFC5234].
+
+ nbn-nss = prefix "-" nbn-string
+
+ prefix = iso-cc *( ":" subspc )
+ ; The entire prefix is case insensitive.
+
+ iso-cc = 2ALPHA
+ ; Alpha-2 country code as assigned by part 1 of ISO 3166
+ ; (identifies the national library to which the branch
+ ; is delegated).
+
+ subspc = 1*(ALPHA / DIGIT)
+ ; As assigned by the respective national library.
+
+ nbn-string = path-rootless
+ ; The "path-rootless" rule is defined in RFC 3986.
+ ; Syntax requirements specified in RFC 8141 MUST be
+ ; taken into account.
+
+ A colon SHOULD be used within the prefix only as a delimiting
+ character between the ISO 3166-1 country code and sub-namespace
+ code(s), which splits the national namespace into smaller parts.
+
+ The structure (if any) of the nbn_string is determined by the
+ authority for the prefix. Whereas the prefix is regarded as case
+ insensitive, NBN strings can be case sensitive at the preference of
+ the assigning authority; parsers therefore MUST treat these as case
+ sensitive, and any case mapping needed to introduce case
+ insensitivity is the responsibility of the relevant resolution
+ system.
+
+ A hyphen SHOULD be used as the delimiting character between the
+ prefix and the NBN string. Within the NBN string, a hyphen MAY be
+ used for separating different sections of the identifier from one
+ another.
+
+ All two-letter codes are reserved by the ISO 3166 Maintenance Agency
+ for either existing or possible future ISO country codes (or for
+ private use).
+
+ Sub-namespace identifiers MUST be registered on the national level by
+ the national library that assigned the identifier. The list of such
+ identifiers can be made publicly available via the Web.
+
+ Note that because case mapping for ASCII letters is completely
+ reversible and does not lose information, the case used in case-
+ insensitive matching is a local matter. Implementations can convert
+
+
+
+Hakala Informational [Page 9]
+
+RFC 8458 NBN URNs October 2018
+
+
+ to lower or upper case as they see fit; they only need to do it
+ consistently.
+
+4.2.1. Usage of r-component and q-component
+
+ URN:NBN resolvers do not currently support the use of either
+ r-component or q-component.
+
+ Resolution services based on r-component can be implemented in the
+ future when the r-component syntax and semantics have been specified.
+
+4.2.2. Usage of f-component
+
+ If URN:NBN resolves to the identified resource and the media type of
+ the resource supports f-component usage, it can be used to indicate a
+ location within the identified resource. Persistence is achieved if
+ the URN:NBN is assigned to one and only one version of a resource,
+ such as a PDF/A version of a book.
+
+ The URN:NBN namespace does not impose any restrictions of its own on
+ f-component usage.
+
+4.3. Encoding Considerations and Lexical Equivalence
+
+ Expressing NBNs as URNs is usually straightforward, as normally only
+ ASCII characters are used in NBN strings. If this is not the case,
+ non-ASCII characters in NBNs MUST be translated into canonical form
+ as specified in RFC 8141. If a national library uses NBNs that can
+ contain percent-encoded characters higher than U+007F, the library
+ needs to carefully define the canonical transformation from these
+ NBNs into URNs, including normalization forms.
+
+ When an NBN is used as a URN, the NSS MUST consist of three parts:
+
+ o a prefix, structured as a primary prefix, which is a two-letter
+ ISO 3166-1 country code of the library's country, and zero or more
+ secondary prefixes that are each indicated by a delimiting colon
+ character (:) and a sub-namespace identifier;
+
+ o a hyphen (-) as a delimiting character; and,
+
+ o the NBN string.
+
+ Different delimiting characters are not semantically equivalent.
+
+ The syntax and roles of the three parts listed above are described in
+ Section 4.2.
+
+
+
+
+Hakala Informational [Page 10]
+
+RFC 8458 NBN URNs October 2018
+
+
+ If there are several national libraries in one country, these
+ libraries MUST agree on how to divide the national namespace between
+ themselves using this method before the URN:NBN assignment begins in
+ any of these libraries.
+
+ A national library MAY also assign URN:NBN sub-namespaces to trusted
+ organizations such as universities or government institutions. The
+ sub-namespace MAY be further divided by the partner organization.
+ All sub-namespace identifiers used within a country-code-based
+ namespace MUST be registered on the national level by the national
+ library that assigned the code. The national register of these codes
+ SHOULD be made available online.
+
+ Being part of the prefix, sub-namespace identifier strings are case-
+ insensitive. They MUST NOT contain any colons or hyphens.
+
+ Formally, two URN:NBNs are lexically equivalent if they are octet-
+ by-octet equal after the following (conceptional) preprocessing:
+
+ 1. convert all characters in the leading "urn:nbn:" token to a
+ single case;
+
+ 2. convert all characters in the prefix (country code and its
+ optional sub-divisions) to a single case; and,
+
+ 3. convert all characters embedded in any percent-encodings to a
+ single case.
+
+ Models (indicated line break inserted for readability):
+
+ URN:NBN:<ISO 3166 alpha-2 country code>-<assigned NBN string>
+
+ URN:NBN:<ISO 3166 alpha-2 country code>:<sub-namespace code>-\
+ <assigned NBN string>
+
+ Examples:
+
+ URN:NBN:fi-fe201003181510
+
+ urn:nbn:ch:bel-9039
+
+ urn:nbn:se:uu:diva-3475
+
+ urn:nbn:hu-3006
+
+
+
+
+
+
+
+Hakala Informational [Page 11]
+
+RFC 8458 NBN URNs October 2018
+
+
+4.4. Resolution and Persistence of NBN-based URNs
+
+ Eventually, URNs might be resolved with the help of a Global Resolver
+ Discovery Service (GRDS), and URN:NBN syntax makes it possible to
+ locate the relevant resolver. Since no GRDS system has been
+ installed yet in the Internet, URN:NBNs are embedded in HTTP URIs in
+ order to make them actionable in the present Internet. In these HTTP
+ URIs, the authority part must point to the appropriate URN resolution
+ service. For instance, in Finland, the address of the national URN
+ resolver is <http://urn.fi>. Thus, the HTTP URI for the Finnish URN
+ in the example above is <http://urn.fi/URN:NBN:fi-fe201003181510>.
+
+ The country-code-based prefix part of the URN:NBN namespace-specific
+ string will provide a hint needed to find the correct resolution
+ service for URN:NBNs from the GRDS when it is established.
+
+ There are three interrelated aspects of persistence that need to be
+ discussed: persistence of the objects itself, persistence of the
+ identifier, and persistence of the URN resolvers.
+
+ NBNs have traditionally been assigned to printed resources, which
+ tend to be persistent. In contrast, digital resources require
+ frequent migrations to guarantee accessibility. Although it is
+ impossible to estimate how often migrations are needed, hardware and
+ software upgrades take place frequently, and a lifetime exceeding
+ 10-20 years can be considered as long.
+
+ However, it is a common practice to keep also the original and
+ previously migrated versions of resources. Therefore, even outdated
+ versions of resources can be available in digital archives, no matter
+ how old or difficult to use they have become.
+
+ If all versions of a resource are kept, a user who requires
+ authenticity can retrieve the original version of the resource,
+ whereas a user to whom the ease of use is a priority is likely to be
+ satisfied with the latest version. In order to enable the users to
+ find the best match, a national library can link all manifestations
+ of a resource to each other so as to make a user aware of them.
+
+ Thus, even if specific versions of digital resources are not normally
+ persistent, persistent identifiers such as URN:NBNs support
+ information architectures that enable persistent access to any
+ version of the resource, including ones that can only be utilized by
+ using digital archaeology tools such as custom-made applications to
+ render the resource.
+
+
+
+
+
+
+Hakala Informational [Page 12]
+
+RFC 8458 NBN URNs October 2018
+
+
+ Persistence of URN resolvers themselves is mainly an organizational
+ issue that is related to the persistence of organizations maintaining
+ them. As URN:NBN resolution services will be supplied (primarily) by
+ the national libraries, these services are likely to be long lived.
+
+4.5. Additional Considerations
+
+ It is a good idea to apply URN:NBNs (or other persistent identifiers)
+ to all resources that have been prioritized in the organization's
+ digital preservation plan.
+
+ Assignment of URN:NBNs to resources that are known to not be
+ persistent should be considered carefully. URN:NBNs can, however, be
+ applied to resources that have a low-level preservation priority and
+ will not be migrated to more modern file formats or preserved via
+ emulation.
+
+ If the identified version of a resource has disappeared, the
+ resolution process can supply a surrogate if one exists. A surrogate
+ can be, for instance, a more modern digital version of the original
+ electronic resource.
+
+5. URN Namespace ID (NID) Registration for the National Bibliography
+ Number (NBN)
+
+ This URN namespace registration describes how National Bibliography
+ Numbers (NBNs) can be supported within the URN framework; it uses the
+ updated IANA template specified in RFC 8141.
+
+ Namespace Identifier: NBN
+ This namespace ID was formally assigned to the National
+ Bibliography Number in October 2001, when the namespace was
+ registered officially [RFC3188]. Utilization of URN:NBNs had
+ started in demo systems already in 1998. Since 2001, tens of
+ millions of URN:NBNs have been assigned. The number of users of
+ the namespace has grown in two ways: new national libraries have
+ started using NBNs, and many national libraries using the system
+ have formed new liaisons.
+
+ Version: 4
+
+ Date: 2018-04-09
+
+
+
+
+
+
+
+
+
+Hakala Informational [Page 13]
+
+RFC 8458 NBN URNs October 2018
+
+
+ Registrant:
+ Name: Juha Hakala
+ Affiliation: Senior Adviser, The National Library of Finland
+ Email: juha.hakala@helsinki.fi
+ Postal: P.O. Box 15, 00014 Helsinki University, Finland
+ Web URL: http://www.nationallibrary.fi/
+
+ The National Library of Finland registered the namespace on behalf
+ of the Conference of the European National Librarians (CENL) and
+ Conference of Directors of National Libraries (CDNL). The NBN
+ namespace is available for free for the national libraries. They
+ can allow other organizations to assign URN:NBNs and use the
+ resolution services established by the library for free or for a
+ fee. The fees, if collected, can be based on, e.g., the
+ maintenance costs of the system.
+
+ Purpose: See Section 3 of RFC 8458
+
+ Syntax: See Section 4.2 of RFC 8458
+
+ Assignment: See Section 4.1 of RFC 8458
+
+ Security and Privacy: See Section 7 of RFC 8458
+
+ Interoperability:
+ National libraries and their partners usually apply URN:NBNs if a
+ standard identifier such as ISBN is not applicable for the
+ resource to be identified. Some overlap with other URN namespaces
+ is possible.
+
+ URN:NBNs may contain characters which must be percent-encoded, but
+ usually they consist of printable ASCII characters only.
+
+ Resolution: See Section 4.4 of RFC 8458
+
+ Documentation: RFC 8458
+
+ Revision Information:
+ This version of the URN:NBN namespace registration has been
+ updated to use the revised definition of URN syntax from RFC 8141,
+ although usage of r-components is not specified yet. In addition,
+ non-ISO 3166 (country code) based NBNs have been deleted due to
+ lack of deployment. The entire NBN prefix is now specified to be
+ case insensitive in accordance with established practice. This
+ version also includes numerous clarifications based on actual
+ usage of URN:NBNs.
+
+
+
+
+
+Hakala Informational [Page 14]
+
+RFC 8458 NBN URNs October 2018
+
+
+6. IANA Considerations
+
+ IANA has updated the existing registration of the formal URN
+ namespace, "NBN", using the template given above in Section 5.
+
+7. Security Considerations
+
+ This document defines means of encoding NBNs as URNs. A URN
+ resolution service for NBN-based URNs is depicted but only at a
+ generic level; thus, questions of secure or authenticated resolution
+ mechanisms and authentication of users are out of scope of this
+ document.
+
+ Although no validation mechanisms are specified on the global level
+ (beyond a routine check of those characters that require special
+ encoding when employed in URIs), NBNs assigned by any given authority
+ can have a well-specified and rich syntax (including, e.g., fixed
+ length and checksum). In such cases, it is possible to validate the
+ correctness of NBNs programmatically.
+
+ Issues regarding intellectual property rights associated with objects
+ identified by the URN:NBNs are beyond the scope of this document, as
+ are questions about rights to the databases that might be used to
+ construct resolution services.
+
+ Beyond the generic security considerations laid out in the underlying
+ documents listed in the Normative References, no specific security
+ threats have been identified for NBN-based URNs.
+
+8. References
+
+8.1. Normative References
+
+ [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
+ Requirement Levels", BCP 14, RFC 2119,
+ DOI 10.17487/RFC2119, March 1997,
+ <https://www.rfc-editor.org/info/rfc2119>.
+
+ [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,
+ <https://www.rfc-editor.org/info/rfc3986>.
+
+ [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
+ Specifications: ABNF", STD 68, RFC 5234,
+ DOI 10.17487/RFC5234, January 2008,
+ <https://www.rfc-editor.org/info/rfc5234>.
+
+
+
+
+Hakala Informational [Page 15]
+
+RFC 8458 NBN URNs October 2018
+
+
+ [RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
+ (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
+ <https://www.rfc-editor.org/info/rfc8141>.
+
+ [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
+ 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
+ May 2017, <https://www.rfc-editor.org/info/rfc8174>.
+
+8.2. Informative References
+
+ [IANA-URI] IANA, "Uniform Resource Identifier (URI) Schemes",
+ <http://www.iana.org/assignments/uri-schemes>.
+
+ [IANA-URN] IANA, "Uniform Resource Names (URN) Namespaces",
+ <http://www.iana.org/assignments/urn-namespaces>.
+
+ [ISBN-namespace]
+ Griffiths, S., "Namespace Registration for International
+ Standard Book Number (ISBN) ISO 2108:2017",
+ <https://www.iana.org/assignments/urn-formal/isbn>.
+
+ [ISO3166-1]
+ ISO, "Codes for the representation of names of countries
+ and their subdivisions -- Part 1: Country codes",
+ ISO 3166-1:2013, November 2013,
+ <https://www.iso.org/standard/63545.html>.
+
+ [ISO3166MA]
+ ISO, "ISO 3166 Country Codes",
+ <https://www.iso.org/iso/country_codes.htm>.
+
+ [ISSN-namespace]
+ Bequet, G., "Namespace Registration for International
+ Standard Serial Number (ISSN) and Linking ISSN (ISSN-L)
+ based on ISO 3297:2007", June 2017,
+ <https://www.iana.org/assignments/urn-formal/issn>.
+
+ [NBN-Resolving]
+ Deutsche Nationalbibliothek, "URN:NBN Resolver fuer
+ Deutschland und Schweiz: Information ueber Partner
+ Institutionen", <https://nbn-resolving.org/institutions>.
+
+ [PERSID] PersID initiative, 2009-2011, "persid: Building a
+ persistent identifier infrastructure",
+ <http://www.persid.org>.
+
+
+
+
+
+
+Hakala Informational [Page 16]
+
+RFC 8458 NBN URNs October 2018
+
+
+ [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
+ Extensions (MIME) Part Two: Media Types", RFC 2046,
+ DOI 10.17487/RFC2046, November 1996,
+ <https://www.rfc-editor.org/info/rfc2046>.
+
+ [RFC2141] Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141,
+ May 1997, <https://www.rfc-editor.org/info/rfc2141>.
+
+ [RFC2288] Lynch, C., Preston, C., and R. Daniel, "Using Existing
+ Bibliographic Identifiers as Uniform Resource Names",
+ RFC 2288, DOI 10.17487/RFC2288, February 1998,
+ <https://www.rfc-editor.org/info/rfc2288>.
+
+ [RFC2611] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
+ "URN Namespace Definition Mechanisms", BCP 33, RFC 2611,
+ DOI 10.17487/RFC2611, June 1999,
+ <https://www.rfc-editor.org/info/rfc2611>.
+
+ [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, <https://www.rfc-editor.org/info/rfc3044>.
+
+ [RFC3187] Hakala, J. and H. Walravens, "Using International Standard
+ Book Numbers as Uniform Resource Names", RFC 3187,
+ DOI 10.17487/RFC3187, October 2001,
+ <https://www.rfc-editor.org/info/rfc3187>.
+
+ [RFC3188] Hakala, J., "Using National Bibliography Numbers as
+ Uniform Resource Names", RFC 3188, DOI 10.17487/RFC3188,
+ October 2001, <https://www.rfc-editor.org/info/rfc3188>.
+
+ [RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
+ "Uniform Resource Names (URN) Namespace Definition
+ Mechanisms", RFC 3406, DOI 10.17487/RFC3406, October 2002,
+ <https://www.rfc-editor.org/info/rfc3406>.
+
+ [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
+ (SHA and SHA-based HMAC and HKDF)", RFC 6234,
+ DOI 10.17487/RFC6234, May 2011,
+ <https://www.rfc-editor.org/info/rfc6234>.
+
+ [RFC8254] Klensin, J. and J. Hakala, "Uniform Resource Name (URN)
+ Namespace Registration Transition", RFC 8254,
+ DOI 10.17487/RFC8254, October 2017,
+ <https://www.rfc-editor.org/info/rfc8254>.
+
+
+
+
+
+Hakala Informational [Page 17]
+
+RFC 8458 NBN URNs October 2018
+
+
+Appendix A. Significant Changes from RFC 3188
+
+ Numerous clarifications have been made based on a decade of
+ experience with RFC 3188.
+
+ NBNs that are not based on ISO 3166 (country codes) have been removed
+ due to lack of usage.
+
+ In accordance with established practice, the whole NBN prefix is now
+ declared case insensitive.
+
+ The document is based on the new URN syntax specification, RFC 8141.
+
+ Use of query components and fragment components with this namespace
+ is now specified in accordance with RFC 8141.
+
+Acknowledgements
+
+ Revision of RFC 3188 started during the project PersID [PERSID].
+ Later, the revision was included in the charter of the URNbis Working
+ Group and worked on in that group in parallel with what became RFCs
+ 8141 and 8254. The author wishes to thank his colleagues in the
+ PersID project and the URNbis participants for their support and
+ review comments.
+
+ Tommi Jauhiainen has provided feedback on an early draft version of
+ this document. The author wishes to thank Tommi Jauhiainen, Bengt
+ Neiss, and Lars Svensson for the comments they have provided to
+ various draft versions of this document.
+
+ John Klensin provided significant editorial and advisory support for
+ later draft versions of the document.
+
+Contributors
+
+ This document would not have been possible without contributions by
+ Alfred Hoenes.
+
+Author's Address
+
+ Juha Hakala
+ The National Library of Finland
+ P.O. Box 26
+ FIN-00014 Helsinki University
+ Finland
+
+ Email: juha.hakala@helsinki.fi
+
+
+
+
+Hakala Informational [Page 18]
+