< draft-hakala-urn-nbn-rfc3188bis-01.txt   draft-hakala-urn-nbn-rfc3188bis-02.txt >
Network Working Group J. Hakala Network Working Group J. Hakala
Internet-Draft The National Library of Finland Internet-Draft The National Library of Finland
Obsoletes: 3188 (if approved) June 2, 2018 Obsoletes: 3188 (if approved) June 14, 2018
Intended status: Informational Intended status: Informational
Expires: December 4, 2018 Expires: December 16, 2018
Using National Bibliography Numbers as Uniform Resource Names Using National Bibliography Numbers as Uniform Resource Names
draft-hakala-urn-nbn-rfc3188bis-01 draft-hakala-urn-nbn-rfc3188bis-02
Abstract Abstract
National Bibliography Numbers (NBNs) are used by the national National Bibliography Numbers (NBNs) are used by the national
libraries and other organizations in order to identify resources in libraries and other organizations in order to identify resources in
their collections. NBNs are usually applied to resources that are their collections. NBNs are usually applied to resources that are
not catered for by established (standard) identifier systems such as not catered for by established (standard) identifier systems such as
ISBN. ISBN.
A URN (Uniform Resource Names) namespace for NBNs was established in A URN (Uniform Resource Names) namespace for NBNs was established in
2001 in RFC 3188. Since then, a number of European national 2001 in RFC 3188. Since then, a number of European national
libraries have implemented URN:NBN-based systems. libraries have implemented URN:NBN-based systems.
This document replaces RFC 3188 and defines how NBNs can be supported This document replaces RFC 3188 and defines how NBNs can be supported
within the updated URN framework. A revised namespace registration within the updated URN framework. A revised namespace registration
(version 4) compliant to RFC 8141 is included. (version 4) compliant to RFC 8141 is included.
Relationship to earlier documents
This draft replaces draft-ietf-urnbis-rfc3188bis-nbn-urn-04, posted
2012-10-22.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 4, 2018. This Internet-Draft will expire on December 16, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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2. Conventions used in this document . . . . . . . . . . . . . . 5 2. Conventions used in this document . . . . . . . . . . . . . . 5
3. Fundamental Namespace and Community Considerations for NBN . 5 3. Fundamental Namespace and Community Considerations for NBN . 5
3.1. The URN:NBN Namespace . . . . . . . . . . . . . . . . . . 5 3.1. The URN:NBN Namespace . . . . . . . . . . . . . . . . . . 5
3.2. Community Considerations for NBNs . . . . . . . . . . . . 6 3.2. Community Considerations for NBNs . . . . . . . . . . . . 6
4. National Bibliography Number URNs . . . . . . . . . . . . . . 7 4. National Bibliography Number URNs . . . . . . . . . . . . . . 7
4.1. Assignment . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. Assignment . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2.1. Usage of r-component and q-component . . . . . . . . 10 4.2.1. Usage of r-component and q-component . . . . . . . . 10
4.2.2. Usage of f-component . . . . . . . . . . . . . . . . 10 4.2.2. Usage of f-component . . . . . . . . . . . . . . . . 10
4.3. Encoding Considerations and Lexical Equivalence . . . . . 10 4.3. Encoding Considerations and Lexical Equivalence . . . . . 10
4.4. Resolution and Persistence of NBN-based URNs . . . . . . 12 4.4. Resolution and Persistence of NBN-based URNs . . . . . . 11
4.5. Additional considerations . . . . . . . . . . . . . . . . 13 4.5. Additional considerations . . . . . . . . . . . . . . . . 13
5. URN Namespace ID (NID) Registration for the National 5. URN Namespace ID (NID) Registration for the National
Bibliography Number (NBN) . . . . . . . . . . . . . . . . . . 13 Bibliography Number (NBN) . . . . . . . . . . . . . . . . . . 13
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
10.1. Normative References . . . . . . . . . . . . . . . . . . 16 10.1. Normative References . . . . . . . . . . . . . . . . . . 15
10.2. Informative References . . . . . . . . . . . . . . . . . 16 10.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Significant Changes from RFC 3188 . . . . . . . . . 18 Appendix A. Significant Changes from RFC 3188 . . . . . . . . . 18
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 19 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 18
B.1. draft-hakala-rfc3188bis-nbn-urn-00 to draft-ietf- B.1. draft-hakala-rfc3188bis-nbn-urn-00 to draft-ietf-
urnbis-*-00 . . . . . . . . . . . . . . . . . . . . . . . 19 urnbis-*-00 . . . . . . . . . . . . . . . . . . . . . . . 18
B.2. draft-ietf-urnbis-rfc3188bis-nbn-urn-00 to -01 . . . . . 19 B.2. draft-ietf-urnbis-rfc3188bis-nbn-urn-00 to -01 . . . . . 19
B.3. draft-ietf-urnbis-rfc3188bis-nbn-urn-01 to -02 . . . . . 20 B.3. draft-ietf-urnbis-rfc3188bis-nbn-urn-01 to -02 . . . . . 19
B.4. draft-ietf-urnbis-rfc3188bis-nbn-urn-02 to -03 . . . . . 20 B.4. draft-ietf-urnbis-rfc3188bis-nbn-urn-02 to -03 . . . . . 20
B.5. draft-ietf-urnbis-rfc3188bis-nbn-urn-03 to -04 . . . . . 20 B.5. draft-ietf-urnbis-rfc3188bis-nbn-urn-03 to -04 . . . . . 20
B.6. draft-ietf-urnbis-rfc3188bis-nbn-urn-04 (2012-10-22) to B.6. draft-ietf-urnbis-rfc3188bis-nbn-urn-04 (2012-10-22) to
draft-hakala-urn-nbn-rfc3188bis-00 . . . . . . . . . . . 21 draft-hakala-urn-nbn-rfc3188bis-00 . . . . . . . . . . . 20
B.7. draft-hakala-urn-nbn-rfc3188bis-00 (2018-04-15) to -01 . 21 B.7. draft-hakala-urn-nbn-rfc3188bis-00 (2018-06-02) to draft-
hakala-urn-nbn-rfc3188bis-01 . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
One of the basic permanent URI schemes (cf. RFC 3986 [RFC3986], One of the basic permanent URI schemes (cf. RFC 3986 [RFC3986],
[IANA-URI]) is 'URN' (Uniform Resource Name). URNs were originally [IANA-URI]) is 'URN' (Uniform Resource Name). URNs were originally
defined in RFC 2141 [RFC2141]. In 2017, a revision was adopted with defined in RFC 2141 [RFC2141]. In 2017, a revision was adopted with
new definitions and registration procedures [RFC8141]. Any new definitions and registration procedures [RFC8141]. Any
traditional identifier, when used within the URN system, must have a traditional identifier, when used within the URN system, must have a
namespace of its own, registered with IANA [IANA-URN]. National namespace of its own, registered with IANA [IANA-URN]. National
Bibliography Number (NBN) is one such namespace, specified in 2001 in Bibliography Number (NBN) is one such namespace, specified in 2001 in
RFC 3188 [RFC3188]. 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 namepace. Violation of those assumptions could impact the
utility of the NBN URN namespace.
URN:NBNs are in production use in several European countries URN:NBNs are in production use in several European countries
including (in alphabetical order) Austria, Finland, Germany, Hungary, including (in alphabetical order) Austria, Finland, Germany, Hungary,
Italy, the Netherlands, Norway, Sweden, and Switzerland. The URN:NBN Italy, the Netherlands, Norway, Sweden, and Switzerland. The URN:NBN
namespace is collectively managed by these national libraries. URN: namespace is collectively managed by these national libraries. URN:
NBNs have been applied to diverse content including Web archives, NBNs have been applied to diverse content including Web archives,
digitized materials, research data, and doctoral dissertations. They digitized materials, research data, and doctoral dissertations. They
can be used by the national libraries and organizations co-operating can be used by the national libraries and organizations co-operating
with them. with them.
As a part of the initial development of the URN system in the late As a part of the initial development of the URN system in the late
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[RFC3187], and 3044 [RFC3044], respectively. ISBN and ISSN [RFC3187], and 3044 [RFC3044], respectively. ISBN and ISSN
namespaces were made compliant with RFC 8141 [RFC8141] in 2017 by namespaces were made compliant with RFC 8141 [RFC8141] in 2017 by
publishing revised ISSN [ISSN-namespace] and ISBN [ISBN-namespace] publishing revised ISSN [ISSN-namespace] and ISBN [ISBN-namespace]
namespace registrations. namespace registrations.
The term "National Bibliography Number" encompasses persistent local The term "National Bibliography Number" encompasses persistent local
identifier systems that the national libraries and their partner identifier systems that the national libraries and their partner
organizations use in addition to the more formally (and organizations use in addition to the more formally (and
internationally) established identifiers. These partner internationally) established identifiers. These partner
organizations include universities and their libraries and other organizations include universities and their libraries and other
subsidiaries, other research institutions, plus governmental subsidiaries, other research institutions, plus governmental and
organizations and commercial companies such as publishers. Some public organizations. Some national libraries maintain a significant
national libraries maintain a significant number of these liaison number of these liaison relationships; for instance, the German
relationships; for instance, the German National Library had almost National Library had almost 400 by early 2018 [NBN-Resolving].
400 by early 2018 [NBN-Resolving].
In practice, NBN differs from standard identifier systems such as In practice, NBN differs from standard identifier systems such as
ISBN and ISSN because it is not a single identifier system with ISBN and ISSN because it is not a single identifier system with
standard-specified scope and syntax. Each NBN implementer creates standard-specified scope and syntax. Each NBN implementer creates
its own system with its own syntax and assignment rules. Each user its own system with its own syntax and assignment rules. Each user
organization is also obliged to keep track of how NBNs are being organization is also obliged to keep track of how NBNs are being
used; however, within the generic framework set in this document, used; however, within the generic framework set in this document,
local NBN assignment policies may vary considerably. local NBN assignment policies may vary considerably.
Historically, NBNs have been applied in the national bibliographies Historically, NBNs have been applied in the national bibliographies
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3. Fundamental Namespace and Community Considerations for NBN 3. Fundamental Namespace and Community Considerations for NBN
3.1. The URN:NBN Namespace 3.1. The URN:NBN Namespace
NBNs are widely used to identify both hand-held and digital resources NBNs are widely used to identify both hand-held and digital resources
in the collections of national libraries and other institutions that in the collections of national libraries and other institutions that
are responsible for preserving the cultural heritage of their are responsible for preserving the cultural heritage of their
constituents. Resources in these collections are usually preserved constituents. Resources in these collections are usually preserved
for a long time (i.e., for centuries). While the preferred methods for a long time (i.e., for centuries). While the preferred methods
for digital preservation may vary over time and depend on the for digital preservation may vary over time and depend on the
content, the most commonly used one is currently migration. Whenever content, the favorite one has been migration. Whenever necessary, a
necessary, a resource in outdated file format is migrated into a more resource in outdated file format is migrated into a more modern file
modern file format. To the extent possible, all old versions of the format. To the extent possible, all old versions of the resource are
resource are also kept, in order to alleviate the negative effects of also kept, in order to alleviate the negative effects of partially
partially successful migrations and gradual loss of original look and successful migrations and gradual loss of original look and feel that
feel that may accompany even fully successful migrations. When NBNs may accompany even fully successful migrations. When NBN is used to
are used to identify manifestations and there are many of them for a identify manifestations and there are many of them for a single work,
single work, local policy MAY mandate that each manifestation ought local policy can require that each manifestation ought to have its
to have its own NBN. An NBN MAY also be used to identify works and own NBN.
expressions; in such a role it can interconnect the manifestations.
NBNs SHOULD only be used for objects when standard identifiers such NBNs are typically used to identify objects for which standard
as ISBN are not applicable. However, NBNs MAY be used for component identifiers such as ISBN are not applicable. However, NBNs can be
resources even when the resource as a whole qualifies for a standard used for component resources even when the resource as a whole
identifier. For instance, even if a digitized book has an ISBN, JPEG qualifies for a standard identifier. For instance, if a digitized
image files of its pages might be assigned NBNs. These URN:NBNs can book has an ISBN, JPEG image files of its pages might be assigned
be used as persistent links to the pages. 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 The scope of standard identifier systems such as ISBN and ISSN is
limited; they are applicable only to certain kinds of resources. limited; they are applicable only to certain kinds of resources. One
Generally speaking, the role of the NBN is to give (national) of the roles of the NBN is to fill in the gaps left by the standard
libraries an identifier system they can control and that can be used identifiers. Collectively, these identifiers and NBNs cover all
in addition or in parallel to other established systems. resources the national libraries and their partners need to include
Collectively, the standard identifiers and NBNs cover all resources in their collections.
the national libraries and their partners need to preserve for the
long term while recognising that there might be significant overlap
between the systems.
Section 4 below, and particularly Section 4.1, present a more Section 4 below, and particularly Section 4.1, present a more
detailed overview of the structure of the NBN namespace, related detailed overview of the structure of the NBN namespace, related
institutions, and the identifier assignment principles used. institutions, and the identifier assignment principles used.
3.2. Community Considerations for NBNs 3.2. Community Considerations for NBNs
National libraries are the key organizations providing persistent URN National libraries are the key organizations providing persistent URN
resolution services for resources identified with NBNs, independent resolution services for resources identified with NBNs, independent
of their form. National libraries MAY allow other organizations such of their form. As co-ordinators of NBN usage, national libraries
as university libraries or governmental organizations to assign NBNs have allowed other organizations such as university libraries or
to the resources they preserve for the long term. In such case, the governmental organizations to assign NBNs to the resources these
national library MUST co-ordinate the use of NBNs at the national organizations preserve for the long term. In such case, the national
level. National libraries can also provide URN resolution services library co-ordinates the use of NBNs at the national level. National
and technical services to other NBN users. These organizations are libraries can also provide URN resolution services and technical
expected to either establish their own URN resolution services or use services to other NBN users. These organizations are expected to
the technical infrastructure provided by the national library. either establish their own URN resolution services or use the
URN:NBNs are expected to be resolvable and support one or more technical infrastructure provided by the national library. URN:NBNs
resolution services. are expected to be resolvable and support one or more resolution
services.
NBNs MAY be used to identify component resources, but the NBN Although NBNs can be used to identify component resources, the NBN
Namespace does not specify a generic, intrinsic syntax for doing Namespace does not specify a generic, intrinsic syntax for doing
that. However, there are at least two different ways in which that. However, there are at least two different ways in which
component resources can be taken into account within the NBN component resources can be taken into account within the NBN
namespace. namespace.
The simplest and probably the most common approach is to assign a The simplest and probably the most common approach is to assign a
separate NBN for each component resource such as a file containing 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 digitized page of a book, and make no provisions to make such NBNs
discernible in a systematical way from others. The URN:NBN assigned discernible in a systematical way from others.
to the component resource enables direct and persistent access to the
page, which might otherwise be available only via browsing the book
from the title page to the page wanted.
Second, if the stipulations of the URI Generic Syntax [RFC3986] and Second, if the stipulations of the URI Generic Syntax [RFC3986] and
the Internet media type specification [RFC2046] are met, in the Internet media type specification [RFC2046] are met, in
accordance with the provisions in RFC 8141, the URN f-component MAY accordance with the provisions in RFC 8141, the URN f-component can
be attached to URN:NBNs in order to indicate the desired location be attached to URN:NBNs in order to indicate the desired location
within the resource supplied by URN resolution. within the resource supplied by URN resolution.
From the library community point of view it is important that the From the library community point of view it is important that the
f-component is not a part of the NSS and therefore f-component f-component is not a part of the NSS and therefore f-component
attachment does not mean that the relevant component part is attachment does not mean that the relevant component part is
identified. Moreover, the resolution process still retrieves the identified. Moreover, the resolution process still retrieves the
entire resource even if there is an f-component. The fragment entire resource even if there is an f-component. The component part
selection is applied by the resolution client (e.g., browser) to the selection is applied by the resolution client (e.g., browser) to the
media returned by the resolution process. In other words, in this resource returned by the resolution process. In other words, in this
latter case the fragments are logical and physical components of the latter case the component parts are just logical and physical parts
identified resource whereas in the former cases these "fragments" are of the identified resource whereas in the former cases they are
actually complete, independently named entities. independently named entities.
Resources identified by NBNs are not always available in the Resources identified by NBNs are not always available in the
Internet. If one is not and there are no other resolution services Internet. If one is not, the URN:NBN can resolve to a surrogate such
available, the URN:NBN SHOULD resolve to a surrogate such as a as a metadata record describing the identified resource.
metadata record describing the identified resource.
If an NBN identifies a work, descriptive metadata about the work
SHOULD be supplied. The metadata record MAY contain links to
Internet-accessible digital manifestations of the work.
Section 4 below, and particularly its Section 4.4, presents a Section 4 below, and particularly its Section 4.4, presents a
detailed overview of the application of the URN:NBN Namespace as well detailed overview of the application of the URN:NBN Namespace as well
as the principles of, and systems used for, the resolution of NBN- as the principles of, and systems used for, the resolution of NBN-
based URNs. based URNs.
4. National Bibliography Number URNs 4. National Bibliography Number URNs
4.1. Assignment 4.1. Assignment
National Bibliography Number (NBN) is a generic term referring to a National Bibliography Number (NBN) is a generic term referring to a
group of identifier systems administered by the national libraries group of identifier systems administered by national libraries and
and institutions authorized by them. The NBN assignment is typically institutions authorized by them. The NBN assignment is typically
performed by the organization hosting the resource. National performed by the organization hosting the resource. National
libraries are committed to permanent preservation of their deposit libraries are committed to permanent preservation of their deposit
collections. collections.
Assignment of NBN-based URNs MUST be controlled on national level by Assignment of NBN-based URNs is controlled on national level by the
the national library (or national libraries, if there is more than national library (or national libraries, if there is more than one).
one). National guidelines can differ, but the identified resources National guidelines can differ, but the identified resources
themselves SHOULD be persistent. themselves are usually persistent.
Different national URN:NBN assignment policies have resulted in Different national URN:NBN assignment policies have resulted in
varying levels of control of the assignment process. Manual URN:NBN varying levels of control of the assignment process. Manual URN:NBN
assignment by the library personnel provides the tightest control, assignment by the library personnel provides the tightest control,
especially if the URN:NBNs cover only resources catalogued into the especially if the URN:NBNs cover only resources catalogued into the
national bibliography. In most national libraries, the scope of national bibliography. In most national libraries, the scope of
URN:NBN is already much broader than this. Usage rules can vary URN:NBN is already much broader than this. Usage rules can vary
within one country, from one URN:NBN sub-namespace to the next. within one country, from one URN:NBN sub-namespace to the next.
Each national library uses NBNs independently of other national Each national library uses NBNs independently of other national
libraries; apart from this document, there is no global authority libraries; apart from this document, there are no guidelines which
that specifies or controls NBN usage. NBNs as such are unique only specify or control NBN usage. NBNs as such are unique only on the
on the national level. When used as URNs, base NBN strings MUST be national level. When used as URNs, base NBN strings MUST be
augmented with a controlled prefix, which is the particular nation's augmented with a controlled prefix, which is the particular nation's
ISO 3166-1 alpha-2 two-letter country code (referred to as "ISO ISO 3166-1 alpha-2 two-letter country code (referred to as "ISO
country code" below) [ISO3166-1]. These prefixes guarantee country code" below) [ISO3166-1]. These prefixes guarantee
uniqueness of the URN:NBNs at the global scale [Iso3166MA]. uniqueness of the URN:NBNs at the global scale [Iso3166MA].
A national library using URN:NBNs SHOULD specify a local assignment National libraries using URN:NBNs usually specify local assignment
policy for itself; such policy MAY limit the URN:NBN usage to the policies for themselves. Such policy can limit the URN:NBN usage to
information resources stored in the national library's digital e.g. the resources stored in the national library's digital
collections or databases. A more liberal URN:NBN assignment policy collections or databases. Athough this specification does not
MAY be applied, but NBNs assigned to short-lived resources SHOULD NOT specify principles for URN:NBN assignment policies that can be
be made URN:NBNs. applied, NBNs assigned to short-lived resources should not be made
URN:NBNs unless such policy can be justified.
URN:NBN assignment policy SHOULD also clarify the local policy URN:NBN assignment policy can clarify for instance the local policy
concerning identifier assignment to component parts of resources, and concerning identifier assignment to component parts of resources, and
specify with sufficient detail the syntax of local component specify with sufficient detail the syntax of local component
identifiers (if there is one as a discernible part of the NBNs). The identifiers (if there is one as a discernible part of the NBNs). The
policy SHOULD also cover any employed extensions to the default NBN policy can also cover any employed extensions to the default NBN
scope (e.g., to cover identification of metadata elements). scope.
NBNs as such are not unique; different national libraries can assign NBNs as such are locally but not globally unique; two national
the same NBN to different resources. A prefix, based on the ISO libraries can assign the same NBN to different resources. A prefix,
country code as described above, guarantees the uniqueness of based on the ISO country code as described above, guarantees the
URN:NBNs across countries. An NBN, once it has been assigned to a global uniqueness of URN:NBNs. An NBN, once it has been assigned to
resource, MUST be persistent, and therefore URN:NBNs are persistent a resource, MUST be persistent, and therefore URN:NBNs are persistent
as well. as well.
A URN:NBN, once it has been generated from a NBN, MUST NOT be re- A URN:NBN, once it has been generated from a NBN, MUST NOT be re-
used for another resource. used for another resource.
Users of the URN:NBN namespace MUST ensure that they do not assign Users of the URN:NBN namespace MUST ensure that they do not assign
the same URN:NBN twice. Different policies can be applied to the same URN:NBN twice. Different policies can be applied to
guarantee this. For instance, NBNs and corresponding URN:NBNs MAY be guarantee this. For instance, NBNs and corresponding URN:NBNs can be
assigned sequentially by programs in order to avoid human mistakes. assigned sequentially by programs in order to avoid human mistakes.
It is also possible to use printable representations of checksums It is also possible to use printable representations of checksums
such as SHA-1 [RFC6234] as NBNs. such as SHA-1 [RFC6234] as NBNs.
4.2. Syntax 4.2. Syntax
The namespace-specific string (NSS) will consist of three parts: The namespace-specific string (NSS) will consist of three parts:
o a prefix, consisting of an ISO 3166-1 alpha-2 country code and o a prefix, consisting of an ISO 3166-1 alpha-2 country code and
optional sub-namespace code(s) separated by colon(s), optional sub-namespace code(s) separated by colon(s),
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; is delegated) ; is delegated)
subspc = 1*(ALPHA / DIGIT) subspc = 1*(ALPHA / DIGIT)
; as assigned by the respective national library ; as assigned by the respective national library
nbn_string = path-rootless nbn_string = path-rootless
; the "path-rootless" rule is defined in RFC 3986. ; the "path-rootless" rule is defined in RFC 3986.
; syntax requirements specified in RFC 8141 MUST be ; syntax requirements specified in RFC 8141 MUST be
; taken into account. ; taken into account.
Colon MAY be used within the prefix only as a delimiting character 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 between the ISO 3166-1 country code and sub-namespace code(s), which
split the national namespace into smaller parts. split the national namespace into smaller parts.
The structure (if any) of the nbn_string is determined by the The structure (if any) of the nbn_string is determined by the
authority for the prefix. Whereas the prefix is regarded as case- authority for the prefix. Whereas the prefix is regarded as case-
insensitive, NBN strings MAY be case-sensitive at the preference of insensitive, NBN strings can be case-sensitive at the preference of
the assigning authority; parsers therefore MUST treat these as case- the assigning authority; parsers therefore MUST treat these as case-
sensitive; any case mapping needed to introduce case-insensitivity is sensitive; any case mapping needed to introduce case-insensitivity is
the responsibility of the relevant resolution system. the responsibility of the relevant resolution system.
Hyphen MUST be used as the delimiting character between the prefix Hyphen SHOULD be used as the delimiting character between the prefix
and the NBN string. Within the NBN string, hyphen MAY be used for and the NBN string. Within the NBN string, hyphen MAY be used for
separating different sections of the identifier from one another. separating different sections of the identifier from one another.
All two-letter codes are reserved by the ISO 3166 Maintenance Agency All two-letter codes are reserved by the ISO 3166 Maintenance Agency
for either existing and possible future ISO country codes (or for for either existing and possible future ISO country codes (or for
private use). private use).
Sub-namespace identifiers MUST be registered on the national level by Sub-namespace identifiers MUST be registered on the national level by
the national library that assigned the code. The list of such the national library that assigned the identifier. The list of such
identifiers SHOULD be available via the Web. identifiers can be made publicly available via the Web.
Note: Because case mapping for ASCII letters is completely reversible Note: Because case mapping for ASCII letters is completely reversible
and does not lose information, the case used in case-insensitive and does not lose information, the case used in case-insensitive
matching is a local matter; implementations can convert to lower or matching is a local matter; implementations can convert to lower or
upper case as they see fit; they only need to do it consistently. upper case as they see fit; they only need to do it consistently.
4.2.1. Usage of r-component and q-component 4.2.1. Usage of r-component and q-component
URN:NBN resolvers MAY support several services. Some of them have URN:NBN resolvers do not currently support the use of either
been formally specified in RFC 2483; some remain unspecified. r-component or q-component.
Examples of existing relevant services are URI to URL or URLs, URI to
URN or URNs, URI to resource or resources, and URI to resource
metadata. In the latter case it is important to be able to indicate
the preferred metadata format, the completeness of the metadata
record, or the metadata content requested, e.g., a table of contents.
A URN resolver maintained by a national library can utilize for
instance the national bibliography, digital asset management systems,
and digital preservation systems to supply these services.
Examples of services that can be specified and implemented in the
future include requests for the oldest and most original version of
the resource, the latest version of the resource, and rights metadata
related to the resource.
Depending on the technical infrastructure within which digital Resolution services based on r-component can be implemented in the
resources are preserved and made available, any service can be future when the r-component syntax and semantics has been specified.
provided via q-component, r-component or both, as long as the usage
of these components is consistent with RFC 8141 or its successors.
4.2.2. Usage of f-component 4.2.2. Usage of f-component
If URI-to-resource service is used and the media type of a resource If URN:NBN resolves to the identified resource and the media type of
supports the use of an f-component, it can be used to indicate a the resource supports f-component usage, it can be used to indicate a
location within the identified resource because NBNs SHOULD be location within the identified resource. Persistence is achieved if
assigned to one and only one version of a resource, such as a PDF the URN:NBN is assigned to one and only one version of a resource,
version of an article. such as PDF/A version of a book.
The URN:NBN Namespace does not impose any restrictions of its own on The URN:NBN Namespace does not impose any restrictions of its own on
f-component usage. f-component usage.
4.3. Encoding Considerations and Lexical Equivalence 4.3. Encoding Considerations and Lexical Equivalence
Expressing NBNs as URNs is usually straightforward, as only ASCII Expressing NBNs as URNs is usually straightforward, as normally only
characters are allowed in NBN strings. If necessary, NBNs MUST be ASCII characters are used in NBN strings. If this is not the case,
translated into canonical form as specified in RFC 8141. 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 theseNBNs
into URNs, including normalization forms.
When an NBN is used as a URN, the namespace-specific string (NSS) When an NBN is used as a URN, the namespace-specific string (NSS)
MUST consist of three parts: MUST consist of three parts:
o a prefix, structured as a primary prefix, which is a two-letter 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 ISO 3166-1 country code of the library's country, and zero or more
secondary prefixes, each indicated by a delimiting colon character secondary prefixes, each indicated by a delimiting colon character
(:) and a sub-namespace identifier, (:) and a sub-namespace identifier,
o a hyphen (-) as a delimiting character, and o a hyphen (-) as a delimiting character, and
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Different delimiting characters are not semantically equivalent. Different delimiting characters are not semantically equivalent.
The syntax and roles of the three parts listed above are described in The syntax and roles of the three parts listed above are described in
Section 4.2. Section 4.2.
If there are several national libraries in one country, these If there are several national libraries in one country, these
libraries MUST agree on how to divide the national namespace between libraries MUST agree on how to divide the national namespace between
themselves using this method before the URN:NBN assignment begins in themselves using this method before the URN:NBN assignment begins in
any of these libraries. any of these libraries.
A national library MAY also assign its own NBN sub-namespace to A national library MAY also assign URN:NBN sub-namespaces to trusted
trusted organization(s) such as a university or a government organizations such as universities or government institutions. The
institution. The sub-namespace MAY be further divided by the partner sub-namespace MAY be further divided by the partner organization.
organization. All sub-namespace identifiers used beneath a country- All sub-namespace identifiers used within a country-code-based
code-based namespace MUST be registered on the national level by the namespace MUST be registered on the national level by the national
national library that assigned the code. The national register of library that assigned the code. The national register of these codes
these codes SHOULD be made available online. SHOULD be made available online.
Being part of the prefix, sub-namespace identifier strings are case- Being part of the prefix, sub-namespace identifier strings are case-
insensitive. They MUST NOT contain any hyphens. insensitive. They MUST NOT contain any colons or hyphens.
Formally, two URN:NBNs are lexically equivalent if they are octet- Formally, two URN:NBNs are lexically equivalent if they are octet-
by-octet equal after the following (conceptional) preprocessing: by-octet equal after the following (conceptional) preprocessing:
1. convert all characters in the leading "urn:nbn:" token to a 1. convert all characters in the leading "urn:nbn:" token to a
single case; single case;
2. convert all characters in the prefix (country code and its 2. convert all characters in the prefix (country code and its
optional sub-divisions) to a single case; optional sub-divisions) to a single case;
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URN:NBN:fi-fe201003181510 URN:NBN:fi-fe201003181510
urn:nbn:ch:bel-9039 urn:nbn:ch:bel-9039
urn:nbn:se:uu:diva-3475 urn:nbn:se:uu:diva-3475
urn:nbn:hu-3006 urn:nbn:hu-3006
4.4. Resolution and Persistence of NBN-based URNs 4.4. Resolution and Persistence of NBN-based URNs
Eventually, URNs might be resolved with the help of a resolver Eventually, URNs might be resolved with the help of a global resolver
discovery service (RDS). Since no such system has been installed yet discovery service (GRDS), and URN:NBN syntax makes it possible to
in the Internet, URN:NBNs are usually embedded in HTTP URIs in order locate the relevant resolver. Since no GRDS system has been
to make them actionable in the present Internet. In these HTTP URIs, installed yet in the Internet, URN:NBNs are embedded in HTTP URIs in
the authority part must point to the appropriate URN resolution 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 service. For instance, in Finland, the address of the national URN
resolver is <http://urn.fi>. Thus the HTTP URI for the Finnish 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>. in the example above is <http://urn.fi/URN:NBN:fi-fe201003181510>.
The country code-based prefix part of the URN:NBN namespace-specific The country code-based prefix part of the URN:NBN namespace-specific
string will provide a hint needed to find the correct resolution string will provide a hint needed to find the correct resolution
service for URN:NBNs from the global resolver discovery service when service for URN:NBNs from the GRDS when it is established.
it is established.
There are three inter-related aspects of persistence that need to be There are three inter-related aspects of persistence that need to be
discussed: persistence of the objects itself, persistence of the discussed: persistence of the objects itself, persistence of the
identifier, and persistence of the URN resolvers. identifier, and persistence of the URN resolvers.
NBNs have traditionally been assigned to printed resources, which NBNs have traditionally been assigned to printed resources, which
tend to be persistent. In contrast, digital resources require tend to be persistent. In contrast, digital resources require
frequent migrations to guarantee accessibility. Although it is frequent migrations to guarantee accessibility. Although it is
impossible to estimate how often migrations are needed, hardware and impossible to estimate how often migrations are needed, hardware and
software upgrades take place frequently, and a life time exceeding software upgrades take place frequently, and a life time exceeding
10-20 years can be considered as long. 10-20 years can be considered as long.
However, it is a common practice to keep also the original and However, it is a common practice to keep also the original and
previously migrated versions of resources. Therefore even outdated previously migrated versions of resources. Therefore even outdated
versions of resources can be available, no matter how old or versions of resources can be available in digital archives, no matter
difficult to use they have become. how old or difficult to use they have become.
If all versions of a resource are kept, a user who requires If all versions of a resource are kept, a user who requires
authenticity can retrieve the original version of the resource, 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 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 satisfied with the latest version. In order to enable the users to
find the best match, an archive can link all manifestations of a find the best match, a national library can link all manifestations
resource to each other (possibly via a work level metadata record) so of a resource to each other so as to make a user aware of them.
as to make the users aware of them.
Thus, even if specific versions of digital resources are not normally Thus, even if specific versions of digital resources are not normally
persistent, persistent identifiers such as URN:NBNs support persistent, persistent identifiers such as URN:NBNs support
information architectures that enable persistent access to any information architectures that enable persistent access to any
version of the resource, including ones which can only be utilized by version of the resource, including ones which can only be utilized by
using digital archeology tools such as custom made applications to using digital archeology tools such as custom made applications to
render the resource. render the resource.
Persistence of URN resolvers themselves is mainly an organizational Persistence of URN resolvers themselves is mainly an organizational
issue, related to the persistence of organizations maintaining them. issue, related to the persistence of organizations maintaining them.
As URN:NBN resolution services will be supplied (primarily) by the As URN:NBN resolution services will be supplied (primarily) by the
national libraries, these services are likely to be long-lived. national libraries, these services are likely to be long-lived.
4.5. Additional considerations 4.5. Additional considerations
URN:NBNs (or other persistent identifiers) SHOULD be applied to all It is a good idea to apply URN:NBNs (or other persistent identifiers)
resources that have been prioritized in the organization's digital to all resources that have been prioritized in the organization's
preservation plan. digital preservation plan.
URN:NBNs SHOULD NOT be assigned to resources that are known to not be Assignment of URN:NBNs to resources that are known to not be
persistent. URN:NBNs MAY however be applied to resources that have a persistent should be considered carefully. URN:NBNs can however be
low-level preservation priority and will not be migrated to more applied to resources that have a low-level preservation priority and
modern file formats. will not be migrated to more modern file formats or preserved via
emulation.
If the identified version of a resource has disappeared, the If the identified version of a resource has disappeared, the
resolution process SHOULD supply a surrogate if one exists, such as resolution process can supply a surrogate if one exists. A surrogate
the original printed version of a resource, or a more modern digital can be for instance a more modern digital version of the original
version of that resource. electronic resource.
5. URN Namespace ID (NID) Registration for the National Bibliography 5. URN Namespace ID (NID) Registration for the National Bibliography
Number (NBN) Number (NBN)
This URN Namespace registration describes how National Bibliography This URN Namespace registration describes how National Bibliography
Numbers (NBNs) can be supported within the URN framework; it uses the Numbers (NBNs) can be supported within the URN framework; it uses the
updated IANA template specified in RFC 8141. updated IANA template specified in RFC 8141.
Namespace Indentifier: NBN Namespace Indentifier: NBN
This Namespace ID was formally assigned to the National This Namespace ID was formally assigned to the National
skipping to change at page 14, line 20 skipping to change at page 14, line 5
Name: Juha Hakala Name: Juha Hakala
Affiliation: Senior Adviser, The National Library of Finland Affiliation: Senior Adviser, The National Library of Finland
Email: juha.hakala@helsinki.fi Email: juha.hakala@helsinki.fi
Postal: P.O.Box 15, 00014 Helsinki University, Finland Postal: P.O.Box 15, 00014 Helsinki University, Finland
Web URL: http://www.nationallibrary.fi/ Web URL: http://www.nationallibrary.fi/
The National Library of Finland registered the namespace on behalf The National Library of Finland registered the namespace on behalf
of the Conference of the European National Librarians (CENL) and of the Conference of the European National Librarians (CENL) and
Conference of Directors of National Libraries (CDNL). The NBN Conference of Directors of National Libraries (CDNL). The NBN
namespace is available for free for the national libraries. They namespace is available for free for the national libraries. They
MAY allow other organizations to assign URN:NBNs and use the can allow other organizations to assign URN:NBNs and use the
resolution services established by the library for free or for a resolution services established by the library for free or for a
fee. The fees, if collected, should be based on, e.g., the fee. The fees, if collected, can be based on, e.g., the
maintenance costs of the system. maintenance costs of the system.
Purpose: See Section 3 of RFC XXXX Purpose: See Section 3 of RFC XXXX
Syntax: See Section 4.2 of RFC XXXX Syntax: See Section 4.2 of RFC XXXX
Assignment: See Section 4.1 of RFC XXXX Assignment: See Section 4.1 of RFC XXXX
Security and Privacy: See Section 7 of RFC XXXX Security and Privacy: See Section 7 of RFC XXXX
Interoperability: Interoperability:
National libraries and their partners use URN:NBNs only if a National libraries and their partners usually apply URN:NBNs if a
standard identifier such as ISBN is not applicable for the standard identifier such as ISBN is not applicable for the
resource to be identified. Significant overlap with other URN resource to be identified. Some overlap with other URN namespaces
namespaces is therefore unlikely. is possible.
URN:NBNs may contain characters which must be percent-encoded, but URN:NBNs may contain characters which must be percent-encoded, but
usually they consist of printable ASCII characters representing usually they consist of printable ASCII characters only.
themselves.
Resolution: See Section 4.4 of RFC XXXX Resolution: See Section 4.4 of RFC XXXX
Documentation: RFC XXXX Documentation: RFC XXXX
Revision Information: Revision Information:
Version 4 of the URN:NBN namespace was updated to use the revised This version of the URN:NBN namespace registration has beens
definition of URN syntax from RFC 8141. In particular, use of updated to use the revised definition of URN syntax from RFC 8141,
query components and fragment components is now specified. In although usage of r-components is not specified yet. In addition,
addition, non-ISO 3166 (country code) based NBNs have been removed non-ISO 3166 (country code) based NBNs have been deleted due to
due to lack of deployment. The entire NBN prefix is now specified lack of deployment. The entire NBN prefix is now specified to be
to be case-insensitive in accordance with established practice. case-insensitive in accordance with established practice. This
This version also includes numerous clarifications based on a version also includes numerous clarifications based on actial
decade of experience with RFC 3188. usage of UR:NBNs.
6. IANA Considerations 6. IANA Considerations
IANA is asked to update the existing registration of the Formal URN IANA is asked to update the existing registration of the Formal URN
Namespace 'NBN' using the template given above in Section 5. Namespace 'NBN' using the template given above in Section 5.
7. Security Considerations 7. Security Considerations
This document defines means of encoding NBNs as URNs. A URN This document defines means of encoding NBNs as URNs. A URN
resolution service for NBN-based URNs is depicted, but only at a resolution service for NBN-based URNs is depicted, but only at a
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8141 and RFC 8254. The author wishes to thank his colleagues in the 8141 and RFC 8254. The author wishes to thank his colleagues in the
PersID project and the URNbis participants for their support and PersID project and the URNbis participants for their support and
review comments. review comments.
Tommi Jauhiainen has provided feedback on an early version of this Tommi Jauhiainen has provided feedback on an early version of this
draft. The author wishes to thank Tommi Jauhiainen, Bengt Neiss, and draft. The author wishes to thank Tommi Jauhiainen, Bengt Neiss, and
Lars Svensson for the comments they have provided to various versions Lars Svensson for the comments they have provided to various versions
of this draft. of this draft.
John Klensin provided significant editorial and advisory support for John Klensin provided significant editorial and advisory support for
late versions of the draft. later versions of the draft.
9. Contributors 9. Contributors
This document would not have been possible without contributions by This document would not have been possible without contributions by
Alfred Hoenes. Alfred Hoenes.
10. References 10. References
10.1. Normative References 10.1. Normative References
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o Conversion of document to XML2RFC format, change of name (not a WG o Conversion of document to XML2RFC format, change of name (not a WG
task). task).
o Adjusted for changes to 2141bis, consolidation of RFC 3406bis, o Adjusted for changes to 2141bis, consolidation of RFC 3406bis,
creation of transition document. creation of transition document.
o Made a number of changes to reflect publication of RFC 8141 o Made a number of changes to reflect publication of RFC 8141
(previously 2141bis and 3406bis) and update terminology, (previously 2141bis and 3406bis) and update terminology,
references, and current status to early 2018. references, and current status to early 2018.
B.7. draft-hakala-urn-nbn-rfc3188bis-00 (2018-04-15) to -01 B.7. draft-hakala-urn-nbn-rfc3188bis-00 (2018-06-02) to draft-hakala-
urn-nbn-rfc3188bis-01
o Extensive editorial corrections in response to issues identified o Adjusted on the basis of feedback from IESG.
during IETF Last Call
o Theoretical discussion on the usage of r- and q-components has
been deleted.
o Out-of-date sections of the text have been updated.
Author's Address Author's Address
Juha Hakala Juha Hakala
The National Library of Finland The National Library of Finland
P.O. Box 15, Helsinki University P.O. Box 15, Helsinki University
Helsinki, MA FIN-00014 Helsinki, MA FIN-00014
Finland Finland
Email: juha.hakala@helsinki.fi Email: juha.hakala@helsinki.fi
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