IETF URNbis WG J. Hakala
Internet-Draft The National Library of Finland
Obsoletes: 3188 (if approved) A. Hoenes, Ed.
Intended status: Standards Track TR-Sys
Expires: June 25, 2011 December 22, 2010
Using National Bibliography Numbers as Uniform Resource Names
draft-ietf-urnbis-rfc3188bis-nbn-urn-00
Abstract
National Bibliography Numbers, NBNs, are widely used by the national
libraries and other organizations in order to identify various
resources such as monographs pre-dating the emergence of the ISBN
system or still images. NBNs are applied to all kinds of resources
that do not have an established identifier system of their own.
Since 2001, there has been a URN (Uniform Resource Names) namespace
for NBNs, and during 2001-2009 millions of URN-based unique and
persistent NBNs have been assigned. The namespace registration was
performed in RFC 3188 and applied to the NBNs known at that point.
No URN:NBN resolution services existed at the time when the RFC was
written. Since then, several countries including Finland, Germany,
Italy, and the Netherlands have used URN:NBNs to identify electronic
resources and to provide persistent links to them. To this end,
these countries have established URN:NBN resolution services that
supply URN - URL linking.
This document replaces RFC 3188 and defines how NBNs can be supported
within the URN framework. An updated namespace registration is
included.
Discussion
This document is an outcome of work performed in 2009-2010 as a part
of the project PersID (http://www.persid.org) and brought into the
IETF; it formally introduces the RFC 3188bis work from PersID as a
chartered work item of the URNbis WG.
Comments are welcome and should be directed to the urn@ietf.org
mailing list or the authors.
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Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Conventions used in this document . . . . . . . . . . . . . . 5
3. Fundamental Namespace and Community Considerations . . . . . . 5
3.1. The URN:NBN Namespace . . . . . . . . . . . . . . . . . . 5
3.2. Community Considerations for NBNs . . . . . . . . . . . . 6
4. National Bibliography Numbers (NBNs) . . . . . . . . . . . . . 7
4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Encoding Considerations and Lexical Equivalence . . . . . 9
4.3. Resolution of NBN-based URNs . . . . . . . . . . . . . . . 11
4.4. Additional Considerations . . . . . . . . . . . . . . . . 12
4.5. URN Namespace ID Registration for the National
Bibliography Number (NBN) . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 19
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Normative References . . . . . . . . . . . . . . . . . . . 19
8.2. Informative References . . . . . . . . . . . . . . . . . . 20
Appendix A. Draft Change Log . . . . . . . . . . . . . . . . . . 21
A.1. draft-hakala-rfc3188bis-nbn-urn-00 to
draft-ietf-urnbis-*-00 . . . . . . . . . . . . . . . . . . 21
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1. Introduction
One of the basic permanent URI schemes (cf. RFC 3986 [RFC3986],
[IANA-URI]) is 'URN' (Uniform Resource Name) as originally defined in
RFC 2141 [RFC2141] and now being formally specified in RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn]. Any identifier, when used within
the URN system, needs its own namespace. As of this writing, there
are roughly 40 registered URN namespaces (see [IANA-URN]), one of
which belongs to NBN, National Bibliography Number, as specified 2001
in RFC 3188 [RFC3188].
Currently URN:NBNs are in production use in several European
countries including (in alphabetical order) Austria, Finland,
Germany, Italy, the Netherlands, Norway, Sweden, and Switzerland.
Several other countries in Europe and elsewhere are considering usage
of them. URN:NBNs have been applied to, e.g., Web archives,
digitized materials, and doctoral dissertations.
As part of the validation process for the development of URNs back in
the late 1990s, the IETF URN working group agreed that it was
important to demonstrate that a URN syntax proposal can accommodate
existing identifiers from well-established namespaces.
One such infrastructure for assigning and managing names comes from
the bibliographic community. Bibliographic identifiers function as
names for objects that exist both in print and, increasingly, in
electronic formats. RFC 2288 [RFC2288] investigated the feasibility
of using three identifiers (ISBN, ISSN and SICI, see below) as URNs,
with positive results; however, it did not formally register
corresponding URN namespaces. This was in part due to the still
evolving process to formalize criteria for namespace definition
documents and registration, consolidated later in the IETF into RFC
3406 [RFC3406]. That RFC, in turn, is now being updated as well into
RFC 3406bis [I-D.ietf-urnbis-rfc3406bis-urn-ns-reg].
URN Namespaces have subsequently been registered for NBN (National
Bibliography Number), ISBN (International Standard Book Number), and
ISSN (International Serial Standard Number) in RFCs 3188 [RFC3188],
3187 [RFC3187], and 3044 [RFC3044], respectively. However, there is
no registered namespace for SICI (Serial Item and Contribution
Identifier), and no plans to make such registration, due to the lack
of use of that standard. The ISBN namespace registration is being
revised so that it covers both ISBN-10 and ISBN-13;
[I-D.ietf-urnbis-rfc3187bis-isbn-urn]. The current ISSN registration
still does not cover ISSN-L, defined in the new version of ISSN; the
URNbis WG will provide an updated namespace registration in
[RFC3044bis].
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Please note that NBN differs from the other identifiers listed above
because it is not a single identifier system and there is no standard
describing NBN systems in use. The term "National Bibliography
Number" encompasses all local identifier systems that the national
libraries and their partner organizations use in addition to the more
formally (and internationally) established identifiers.
Historically, they were only applied in the national bibliographies
to identify the resources catalogued into it. During the last 10
years, the NBN scope has been extended to cover a vast range of
digital resources available via the Internet. Only a minority of
these resources are catalogued in the national bibliographies or
other bibliographical databases.
Guidelines for using NBNs as URNs and the original namespace
registration have been published in RFC 3188 [RFC3188]. The RFC at
hand replaces RFC 3188; sections discussing the methods in which URN:
NBNs can be resolved have been updated and the text is also made
compliant with the stipulations of RFC 3406bis
[I-D.ietf-urnbis-rfc3406bis-urn-ns-reg], the successor of RFC 3406
[RFC3406], which previously had replaced RFC 2611 [RFC2611] that was
applied in the initial registration.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
NBN refers to any National Bibliography Number identifier system used
by the national libraries and other institutions using the system
with the national library's permission.
3. Fundamental Namespace and Community Considerations
3.1. The URN:NBN Namespace
NBNs identify objects covered by legal requirements on national
libraries and similar institutions to preserve the cultural
inheritage of their constituents. They are predominantly used for
objects that have not been assigned other, more specific, standard
identifiers that could be used to identfy them in catalogues and
other collections of metadata.
Therefore, to the same extent as NBNs are used to close gaps between
existing, more universal, but also more specific, identifier systems
(like ISBN and ISSN), a dedicated URN namespace is needed to map
these identifiers into the URN system and thus make them actionable
for URN resolution systems.
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Section 4 below, and there in particular Section 4.1, presents a
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. National libraries may however allow other
organizations such as university libraries or governmental
organizations to assign NBNs to their resources. In such case the
national library will co-ordinate the use of NBNs and support the NBN
users in guaranteeing the persistence of these resources and
resolution. These other organizations may establish their own
resolution services or they may use the infrastructure provided by
the national library.
NBNs identify finite objects, but sometimes these objects might be so
large or complex that identification of fragments is appropriate (in
addition to identification of the resource itself). The materials
identified by an NBN will often be digital, but they may also exist
only in printed or other physical form. In such a case, the URN:NBN
resolver should nevertheless be able to supply, e.g., a description
of the resource, possibly including the address where the resource is
available.
National bibliography numbers enable the national libraries and
organizations which liaise with them to uniquely identify resources
and provide persistent links to the resource accessible in the
Internet. Since most digital documents held in national libraries'
digital collections are not eligible for other, more formal
identifiers such as ISBN, NBNs are a valuable asset for the
community. A proof of this are the millions of URN:NBNs that have
been allocated since the NBN namespace was registered, and the
operational services that have been built, using these identifiers
and resolver applications.
For library users, URN-based identification and resolution services
mean more efficient and reliable access to resources. No special
tools are needed for this; Web browsers are sufficient. The users
may also be able to acquire URN:NBNs to their own works such as a
university thesis.
Section 4 below, and in particular Section 4.3 therein, presents a
detailed overview of the application of the URN:NBN namespace and the
principles, and systems used, for the resolution of NBN-based URNs.
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4. National Bibliography Numbers (NBNs)
4.1. Overview
National Bibliography Number (NBN) is a generic name referring to a
group of identifier systems administered by the national libraries
and institutions authorized by them. The NBN assignment is typically
performed by the organization hosting the resource. These
organizations (national libraries and institutions in liaison with
them) are usually committed to preserving their collections for a
long time -- at least decades, and possibly centuries. National
libraries give NBNs to resources belonging to the (legal) deposit
collections which by default will be kept as long as possible, but
not to resources considered ephemeral.
Each national library uses its own NBNs independently of other
national libraries; there is no global authority that controls NBN
usage. For this reason, NBNs as such are unique only on a national
level. When used as URNs, NBN strings MUST be augmented with a
controlled prefix such as the ISO 3166-1 alpha-2 two-letter country
code. These prefixes guarantee uniqueness of the NBN-based URNs on
the global scale [Iso3166MA].
NBNs have traditionally been given to documents that do not have a
formal (standard) identifier, but are catalogued to the national
bibliography. Examples of this include books that predate the
introduction of the ISBN in the 1970s, or modern books that for some
reason have not received an ISBN. NBNs can be seen as a fall-back
mechanism: if no other, standards-based identifier such as an ISBN
can be given, an NBN is assigned.
URNs may also be used in universities' open repositories when a
resource already has another identifier -- for instance, a Handle
required by the open archive software, or a DOI (Digital Object
Identifier) -- that can only be resolved in a publisher's (or third
party's) resolution service. Such persistent identifier cannot be
used to provide linking to the open repository or legal deposit
collection. URN:NBN-based resolution can deliver that, and may also
be extended to include access to other repositories holding the same
resource.
In principle, NBNs enable identification of any kind of resource,
such as still images published in periodical articles, or short
stories and poems published in book form or in the Web. Local
policies may limit the NBN usage to for instance documents stored
permanently in the national library's collections. Following the
initial registration of a URN namespace for NBN, several countries
broadened the scope of NBN assignment significantly to cover broader
scope of their digital materials.
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Some national libraries (e.g., Finland, Norway, Sweden) have
established Web-based URN generators, which enable authors and
publishers to fetch NBN-based URNs for their network resources.
There are also applications, used for instance in digitization
processes, that assign NBNs automatically to resources or even their
component parts such as still images published in monographs or
serials.
Within the limitations set by RFC 2141[bis], this document, and other
relevant RFCs, both syntax and scope of local NBNs can be decided by
each national library independently. Historically, NBNs have
consisted of one or more letters and/or digits. For instance,
(Finnish) NBN for the Romanian translation of the Finnish classic
"Seven Brothers" published in 1957 is f568471. URN strings can
contain encoded UNICODE characters, as specified in the declaration
of syntactic structure, and there are no length limitations.
Therefore, literally billions of NBNs can be allocated, which makes
them suitable for, e.g., naming of Web documents.
In Italy a novel hierarchical distributed architecture for NBN
assignment has been designed, in order to eliminate the single-point-
of-error risks of a centralised system and to reduce the costs of
managing a resolution service based on persistent identifiers.
The Central National Library in Florence manages the national domain
NBN:IT and the national URN resolution service that contains every
URN:NBN assigned in Italy. The library has supplied URN:NBN:IT sub-
domains to trusted institutions and bodies such as universities that
are responsible for digital collections and routinely manage digital
resources, for instance via creating and updating metadata on these
resources, including location (URL) information. All these
institutions have their own resolution services, but the URN - URL
mappings in them are periodically harvested to the national
resolution service using the Open Archives Initiative Protocol for
Metadata Harvesting (OAI-PMH; see
(<http://www.openarchives.org/OAI/openarchivesprotocol.html>).
Harvesting the data to the central node enables distributed service.
The central node can serve the users when the local node is not
functional. This architecture increases the robustness of the
network via duplication of resolution services and enables peer-to-
peer resolution between the second-level institutions. Moreover, it
is possible to add yet another layer to the network by creating an
international node, which shall contain all the data from the
national nodes. Such international service may also be created by
building a virtual union resolver that uses all the national nodes.
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The PersID project is implementing such a system at the European
level.
4.2. Encoding Considerations and Lexical Equivalence
Embedding NBNs within the URN framework initially did not present any
particular encoding problems, since the ASCII characters utilized in
traditional NBN systems belonged to the URN character set. Machine
generated NBNs may be more demanding; if necessary, NBNs must be
translated into canonical form as specified in RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn].
When an NBN is used as a URN, the namespace-specific string must
consist of three parts:
o a prefix, consisting of either a two-letter ISO 3166-1 country
code or another registered string,
o a delimiting character that is either hyphen (-) or colon (:), and
o the NBN string.
ISO 3166-1 country codes and other registered prefix strings are
case-insensitive. The NBN string may be case sensitive.
Different delimiting characters are not lexically equivalent.
A hyphen MUST be used for separating the prefix and the NBN string.
A colon MAY be used as the delimiting character if and only if a
country code-based NBN namespace is split further into smaller sub-
namespaces.
If there are several national libraries in one country, these
libraries can divide the national namespace between themselves using
this method.
A national library MAY also assign to trusted organization(s) such as
a university or a government institution its own NBN sub-namespace.
For instance, the national library of Finland has given Statistics
Finland (<http://www.stat.fi/index_en.html>) a sub-namespace "st"
(i.e., urn:nbn:fi:st). These trusted organizations must follow the
general rules of the NBN usage provided by the national library, and
take care of the long-term preservation of the identified resources
in order to guarantee persistence.
Sub-namespace identifier strings are case-insensitive.
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Non-ISO 3166-1 alpha-2 prefixes, if used, MUST be registered on the
global level. The U.S. Library of Congress maintains the central
register of assigned non-ISO 3166-1 prefix strings together with the
name and contact information of the registrant. Each prefix MUST
have one and only one user organization, which is responsible for
maintaining the delegated sub-namespace according to the general
rules set out in this document.
Since the setup of that registry, and up to the time of this
writing, no such prefixes have been registered, and it is expected
that demand will remain low. Therefore, no more complicated rules
(for instance for a hierarchical structure of such prefixes), are
specified here. For this unlikely case of unexpected future
needs, a revision of this document would be needed to accommodate
that.
[[ Note: If the NBN community does not see a need to maintain this
-- so far unused -- option for prefixes not based on ISO 3166-1,
it could be dropped without breaking backwards compatibility.
Another option to consider would be migrating the registry to IANA
if that would be preferred by the Library of Congress. ]]
Sub-namespace codes beneath 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.
All two-letter prefixes are reserved for existing and possible future
ISO country codes (or for private use) [Iso3166MA] and MUST NOT be
used as non-ISO country-code prefixes. If there are several national
libraries in one country that use the same country code as a shared
prefix, they need to agree on how to divide the namespace. They may
either share one namespace but agree on how to avoid assigning
duplicate identifiers, or they may split the namespace into library-
specific sub-namespaces.
Models (indicated linebreak 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>
URN:NBN:<non-ISO 3166 prefix>-<assigned NBN string>
Examples (using actually assigned NBNs):
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URN:NBN:fi-fe201003181510
urn:nbn:ch:bel-9039
urn:nbn:se:uu:diva-3475
urn:nbn:hu-3006
From the libraries' point of view, one of the key benefits of using
URNs and other persistent identifiers is that there is only one
location -- the resolution service -- where the linking infomation
has to be maintained. If bibliographic records in libraries' on-line
public access catalogues (OPACs) contain URLs, then each record must
be modified whenever the URL changes. This may mean hundreds of
changes for a popular resource. With URNs, only the URN - URL
linking in the mapping table of the resolution servicem needs to be
kept up-to-date. All links in the bibliographic records point to the
resolution service where the URN is translated to one or more URL(s).
4.3. Resolution of NBN-based URNs
[[ Editorial Note: the text below needs to be revisited once the
perspective of the list of URN services in RFC 2483 has been
discussed and resolved by the WG. ]]
URNs can be used to provide various services. RFC 2483 [RFC2483]
gives a few examples, such as retrieving a single URL or all URLs
applying to the resource. The constant development of digital
library applications has widened the scope of the services needed,
which has meant that RFC 2483 is becoming more outdated all the time.
Resolution services available may vary from one URN resolver to the
next, depending on the technical implementation of the resolver and
the target system contacted. Please note that services MUST NOT be
hard coded into the URN itself when the identifier is assigned.
Eventually, URN:NBNs will be resolved with the help of a resolver
discovery service (RDS). No such system has been installed yet in
the Internet infrastructure. Therefore, URN:NBNs should be 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. In Finland, the address of the
national URN resolver is <http://urn.fi>. Thus the HTTP URI for the
URN in the example is <http://urn.fi/URN:NBN:fi-fe201003181510>.
This URL in turn resolves to the actual address of the thesis, which
as of this writing (2010-03-27) was <https://oa.doria.fi/bitstream/
handle/10024/59475/inandout.pdf?sequence=1>.
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The country code-based prefix part of the URN namespace-specific
string will provide a guide to finding the correct national
resolution service for URN:NBNs from the resolver discovery service
when it is established. If there are multiple URN:NBN resolvers in
the country, there are two possible approaches for making sure that
RDS will work. All URN:NBNs mappings can be harvested to the
national node (the Italian approach). The other approach is to make
the RDS aware of all the URN:NBN resolution services, and specify in
the RDS which parts of the national URN:NBN namespace they are
capable of serving.
URN:NBN - URL mappings maintained nationally can be harvested using,
e.g., OAI-PMH from abroad to other national and international URN
resolvers. This makes it possible to improve the reliability of the
system; if the Finnish national resolver node does not respond, its
URN - URL mappings may be available at other resolvers.
Persistence of any resolution service is not only a technical issue,
but also an organizational and legal one. National libraries are in
ideal position to provide persistent resolution services, since most
of them maintain (legal) deposit collections, in which domestic
publications shall be preserved for future generations. Increasingly
these collection contain also digital resources.
4.4. Additional Considerations
Guidelines adopted and promoted by each national library define when
different manifestations of a work should be assigned the same or
differing NBNs. But some simple guidelines should be followed by all
users of the namespace. Manifestations with significantly different
semantic content -- following for instance a migration that failed to
retain all content -- must not have the same NBN. Manifestations
that have the same content but different look and feel, or
manifestations that look (almost) identical but have significant
technical differences (such as the same text document as Word 2003
file and OOXML file, or the same image as uncompressed TIFF and JPEG
2000) should not have the same NBN. If there are several copies of
the file hosted by one organization, each copy must have the same
NBN. If the NBN is based on a checksum (such as MD5, see RFC 1321
[RFC1321]), the resources that are identical at the bit level will
receive the same NBN. Dissimilar resources may in theory get the
same checksum; with a reliable message digest algorithm such
probability is however very small.
The rules governing the usage of NBNs are local and usually less
strict than those specifying the usage of ISBNs and other standard
identifiers. As long as the NBNs were assigned only in the national
libraries, the identifier use was however well co-ordinated in
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practice. Now, following significant broadening in the scope of the
NBN to cover Web resources, NBN assignment is less tightly
controlled. Works may have several manifestations that may be almost
identical. For instance, a single photo can published in many
electronic newspapers in different countries. Since there is no
standard identifier for still images, such a photo is likely to
receive multiple NBN, one in each national web archive. Printed
materials will also cause problems when dititized. If two
organizations are digitizing the same resources and use NBNs for
identification of these resources, the result will be duplicate NBN
assignment since NBNs as a rule have national scope, and these
organizations may not be aware of each other. If the metadata
describing the resource is harvested into a common service, and the
bibliographic records are similar enough to be merged, the user may
see two NBNs and HTTP URIs pointing to two different resolution
services and physical copies of the same resource. If the two copies
had the same identifier such as an ISBN, there would still be two
HTTP URIs providing access to different physical copies of the
resource since the locations of the resolution services will differ.
If the same resource -- for instance, a master's thesis published by
two universities -- is held in two repositories located in different
NBN-sub-namespaces within one national namespace, these copies may
also receive different NBNs especially if there is no easy way of
checking if the resource has already been identified somewhere. In
this case, duplication may be revealed in the national level when the
metadata records of the two copies are compared. In such case, like
in the previous example, both URN:NBNs are equally valid.
4.5. URN Namespace ID Registration for the National Bibliography Number
(NBN)
This registration describes how National Bibliography Numbers (NBNs)
can be supported within the URN framework.
[[ RFC Editor: please replace "XXXX" in all instances of "RFC XXXX"
below by the RFC number assigned to this document. ]]
Namespace ID: NBN
This Namespace ID was formally assigned to the National
Bibliography Number in October 2001 when the namespace was
registered officially. Utilization of URN:NBNs started in
demonstrator systems in 1998; since then, 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 some national libraries already using the system have formed
new liaisons.
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Registration Information:
Version: 4
Date: 2010-12-22
Declared registrant of the namespace:
Name: Mr. 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), which have
both made a commitment in 1998 to foster the use of URNs. The NBN
namespace is available for free for all national libraries in the
world. The national libraries may allow other organizations use
the namespace for free or for a fee.
Declaration of syntactic structure of NSS part:
The namespace-specific string (NSS) will consist of three parts:
a prefix, consisting of either an ISO 3166-1 alpha-2 country
code or other registered string and sub-namespace codes,
delimiting characters (colon (:) and hyphen (-)), and
an NBN string assigned by the national library or sub-delegated
authority.
Formal declaration of the NSS, using ABNF [RFC5234]:
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nbn_nss = prefix "-" nbn_string
prefix = cc_prefix / reg_prefix
; these prefixes are case-insensitive
cc_prefix = iso_cc *( ":" subspc )
iso_cc = 2ALPHA
; country code as assigned by ISO 3166, part 1 --
; identifies the national library
; to which the branch is delegated
subspc = 1*(ALPHA / DIGIT)
; as assigned by the respective national library
reg_prefix = 3*(ALPHA / DIGIT)
; as assigned by the Library of Congress --
; identifies a trusted third party
; to which the branch is delegated
nbn_string = <specific per prefix>
; MUST adhere to RFC 3986 <path-rootless> syntax;
; parsers must regard nbn_strings as case-sensitive
Colon may be used as a delimiting character only within the
prefix, between ISO 3166-1 country code and sub-namespace code(s),
which split the national namespace into smaller parts.
Dividing non-ISO 3166-based namespaces further with sub-namespace
codes MUST NOT be done.
Whereas all prefixes are regarded as case-insensitive, NBN-strings
MAY be case-insensitive at the preference of the assigning
authority; parsers therefore MUST treat these as case-sensitive;
any case mapping needed to introduce case-insensitivity MUST be
implemented in the responsible resolution system.
Hyphen MUST be used as the delimiting character between the prefix
and the NBN string. Within the NBN string, hyphen MAY be used for
separating different sections of the identifier from one another.
Non-ISO prefixes used instead of the ISO country code must be
registered. A global registry, maintained by the Library of
Congress, has beeen created and made available via the Web.
Contact information: <mailto:nbn.register@loc.gov.us>.
All two-letter codes are reserved for existing and possible future
ISO country codes and MUST NOT be used as non-ISO prefixes.
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Sub-namespace codes MUST be registered on the national level by
the national library that assigned the code. The list of such
codes SHOULD be available via the Web.
Models (indicated linebreak inserted for readability):
URN:NBN:<ISO 3166 country code>-<assigned NBN string>
URN:NBN:<ISO 3166 country code:sub-namespace code>-\
<assigned NBN string>
URN:NBN:<non-ISO 3166 prefix>-<assigned NBN string>
Example:
urn:nbn:de:gbv:089-3321752945
Relevant ancillary documentation:
National Bibliography Number (NBN) is a generic name referring to
a group of identifier systems used by the national libraries and
other organizations for identification of deposited publications
and other resources that lack a 'canonical' identifier, or to
descriptive metadata (cataloguing) that describes the resources.
Each national library uses its own NBN system independently of
other national libraries; there is neither a general standard
defining NBN syntax nor a global authority to control the use of
these identifier systems.
Each national library decides locally which resources shall
receive NBNs. These identifiers have traditionally been assigned
to documents that do not have a publisher-assigned identifier, but
are nevertheless catalogued to the national bibliography.
Typically identification of grey publications have largely been
dependent on NBNs. With the introduction of the Internet and URN:
NBN namespace in 1998, the scope of NBN assignment has been
extended to a broad spectrum of Internet resources including,
e.g., harvested Web pages.
Some national libraries (Finland, Norway, Sweden) have established
Web-based URN generators that enable authors and publishers to
fetch NBN-based URNs for the resources they publish in the Web.
The most significant group of publications to which NBNs have been
applied are doctoral theses.
The syntax of NBNs is decided by each national library
independently. Historically, NBNs used in national bibliographies
contained only characters that belong to the URN character set.
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Following the expansion of NBN scope and semi- and fully automated
NBN assignment processes, some NBNs may contain characters that
must be translated into canonical form according to the
specifications in RFC 2141bis [I-D.ietf-urnbis-rfc2141bis-urn].
Conformance with URN syntax:
Traditional NBNs (those applied in the national bibliographies)
consisted of ASCII 7-bit letters and digits (a-z and 0-9). For
instance, the NBN of the first Hungarian translation of the
Finnish national epos Kalevala is f20043425. The book was
published in 1853 and therefore does not have an ISBN. Machine-
generated NBNs must follow the stipulations of RFC 2141bis
[I-D.ietf-urnbis-rfc2141bis-urn].
[[ Editorial Note: Need to discuss new specification requirements
from the RFC 2141bis draft! ]]
Rules for lexical equivalence of NSS part:
Two URN:NBNs are lexically equivalent if they are octet-by-octet
equal after the following (conceptional) preprocessing:
1. normalize the case of the leading "urn:" token
2. normalize the case of the NID
3. normalize the case of the NSS prefix
4. normalize the case of any percent-encoding
Note: The case used in the normalization steps is a local matter;
implementations can normalize to lower or upper case as they see
fit, they only need to do it consistently.
Identifier uniqueness and persistence considerations:
NBN strings assigned by two national libraries may be identical.
In order to guarantee global uniqueness of NBN-based URNs,
therefore a controlled prefix is present in the namespace specific
string. These NBNs, once given to the resource, will be
persistent. Persistence of the resources themselves will be
guaranteed by the national libraries as a part of their legal
deposit activities. This applies to publications and Web
resources only; long-term preservation of other resources such as
governmental documents will be dependent on other actors like
national archives.
An NBN, once it has been assigned, must never be re-used for
another resource.
At the national level, libraries may utilise different policies
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for guaranteeing uniqueness of NBNs. They may be assigned
sequentially by programs (URN generators) in order to avoid human
mistakes. It is also possible to use checksums such as SHA-1 or
MD5 as NBN.
Process of identifier assignment:
Assignment of NBN-based URNs MUST be controlled on national level
by the national library / national libraries. Although the basic
principles are the same, there are differences in scope; for
instance in the Netherlands URN:NBNs are used -- among other
things -- to identify scientific articles stored in the national
library's long-term preservation system. The National Library of
Finland, on the other hand, is using URNs extensively to identify
and provide access to the digitized content. There are also
organizations that use NBN-based URNs to identify data sets. The
common denominator, however, is that the identified resources
themselves are persistent.
National libraries may choose different strategies in assigning
NBN-based URNs, and different approaches have varying levels of
control with respect to the persistence of the documents. Manual
URN assignment by the library personnel only provides the best
possible control, especially if this is done traditionally, that
is, only when the document is catalogued into the national
bibliography. Usually the scope of URN:NBN is much broader than
this; NBNs may for instance be automatically generated for each
archived resource by a long-term preservation system. From
control point of view, the most liberal approach is a URN
generator which builds URNs for everyone, with no guarantee that
the resource identified will be preserved or accessible. Every
national library must decide the degree of freedom it allows to
the URN:NBN users. Usage rules may of course vary from one sub-
namespace to the next. As of yet there are no international
guidelines for NBN use beyond what has been stipulated above, but
more sttringent rules may be developed in the future.
Process for identifier resolution:
See Section 4.3 of RFC XXXX.
Validation mechanism:
None specified on the global level (beyond a routine check of
those characters that require special encoding when employed in
URIs). A national library may use NBNs that contain a checksum
and can therefore be validated, but as of this writing there are
no NBNs which incorporate such checksum.
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Scope:
NBN is an umbrella referring to identifier systems used for
identification of diverse publications and other resources in the
national libraries and their partner organizations.
5. Security Considerations
This document proposes means of encoding NBNs within the URN
framework. A URN resolution service for NBN-based URNs is depicted,
but only at a fairly generic level; thus, questions of secure or
authenticated resolution mechanisms and authentication of users are
out of scope of this document. It does not deal with means of
validating the integrity or authenticating the source or provenance
of URNs that contain NBNs. Issues regarding intellectual property
rights associated with objects identified by the NBNs are also beyond
the scope of this document, as are questions about rights to the
databases that might be used to construct resolution services.
6. IANA Considerations
IANA is asked to update the existing registration of the Formal URN
Namespace 'NBN' using the template given above in Section 4.5.
7. Acknowledgements
This document is an outcome of work performed in 2009-2010 as a part
of the project PersID (http://www.persid.org) that aims at revising
the basic URN RFCs, in order to bring them in alignment with the
current URI Standard (STD 63, RFC 3986), ABNF, and IANA guidelines,
and to establish a modern URN resolution system for bibliographic
identifiers. This work has been brought to the IETF and has lead to
the establishment of the URNbis working group in the Applications
Area. The author wishes to thank his colleagues in the PersID
project for their support.
Your name could go here ...
8. References
8.1. Normative References
[I-D.ietf-urnbis-rfc2141bis-urn]
Hoenes, A., "Uniform Resource Name (URN) Syntax",
draft-ietf-urnbis-rfc2141bis-urn-00 (work in progress),
November 2010.
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[I-D.ietf-urnbis-rfc3406bis-urn-ns-reg]
Hoenes, A., "Uniform Resource Name (URN) Namespace
Definition Mechanisms",
draft-ietf-urnbis-rfc3406bis-urn-ns-reg-00 (work in
progress), December 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
8.2. Informative References
[I-D.ietf-urnbis-rfc3187bis-isbn-urn]
Huttunen, M., Hakala, J., and A. Hoenes, "Using
International Standard Book Numbers as Uniform Resource
Names", draft-ietf-urnbis-rfc3187bis-isbn-urn-00 (work in
progress), December 2010.
[IANA-URI]
IANA, "URI Schemes Registry",
<http://www.iana.org/assignments/uri-schemes/>.
[IANA-URN]
IANA, "URN Namespace Registry",
<http://www.iana.org/assignments/urn-namespaces/>.
[Iso3166MA]
ISO, "ISO Maintenance agency for ISO 3166 country codes",
<http://www.iso.org/iso/country_codes.htm>.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
April 1992.
[RFC2141] Moats, R., "URN Syntax", RFC 2141, May 1997.
[RFC2288] Lynch, C., Preston, C., and R. Jr, "Using Existing
Bibliographic Identifiers as Uniform Resource Names",
RFC 2288, February 1998.
[RFC2483] Mealling, M. and R. Daniel, "URI Resolution Services
Necessary for URN Resolution", RFC 2483, January 1999.
[RFC2611] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"URN Namespace Definition Mechanisms", BCP 33, RFC 2611,
June 1999.
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[RFC3044] Rozenfeld, S., "Using The ISSN (International Serial
Standard Number) as URN (Uniform Resource Names) within an
ISSN-URN Namespace", RFC 3044, January 2001.
[RFC3187] Hakala, J. and H. Walravens, "Using International Standard
Book Numbers as Uniform Resource Names", RFC 3187,
October 2001.
[RFC3188] Hakala, J., "Using National Bibliography Numbers as
Uniform Resource Names", RFC 3188, October 2001.
[RFC3406] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition
Mechanisms", BCP 66, RFC 3406, October 2002.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
Appendix A. Draft Change Log
[[ RFC-Editor: Whole section to be deleted before RFC publication. ]]
A.1. draft-hakala-rfc3188bis-nbn-urn-00 to draft-ietf-urnbis-*-00
- formal updates for a WG draft; no more "Updates: 2288";
- introduced references to other URNbis WG documents;
- changes based on review by Tommi Jauhiainen;
- Sect. 3 restructured into namespace and community considerations;
- old Sect. 7 incorporated in new Sect. 3.1;
- Security Considerations: old Section 4.5 merged into Section 5;
- added guidelines for when two manifestations of the same work
should get different URN:NBNs;
- clarified role of ISO 3166/MA for ISO 3166-1 country codes;
- clarified role of non-ISO prefix registry maintaind by the LoC;
- resolved inconsistency in lexical equivalence rules: as already
specified for ISO alpha-2 country-codes, and in accordance with
established practice, the whole NBN prefix is now declared case-
insensitive;
- registration template adapted to rfc3406bis [-00];
- numerous editorial fixes and enhancements.
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Authors' Addresses
Juha Hakala
The National Library of Finland
P.O. Box 15
Helsinki, Helsinki University FIN-00014
Finland
Email: juha.hakala@helsinki.fi
Alfred Hoenes (editor)
TR-Sys
Gerlinger Str. 12
Ditzingen D-71254
Germany
Email: ah@TR-Sys.de
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