Subject: NID registration for NBN

From: Juha Hakala <[email-masked]>
Date: Tue, 30 Jan 2001 14:24:04 +0200

Dear all,

Please find attached the third and hopefully last version of the URN NID
registration request for national bibliography numbers (NBNs). The text
has already been sent to the Internet drafts editor.

The previous version did not attract criticism from URN community, but
some colleagues from national libraries (especially Ray Denenberg from
the Library of Congress) have provided useful feedback. I have done my
best to accommodate these comments into the present text. No fundamental
changes have been necessary, but the present document should be more
clear, and its English is definitely better (a bunch of missing articles
has been added, for instance).

Some national libraries are already actively assigning URNs based on
NBNs to their electronic resources. Thus we are quite eager to finalise
the NID registration process. Of course, comments are still welcome.

As regards the comments to the ISBN NID registration document sent last
week to the URN list: feedback sent by Michael and Leslie did not leave
much for me to say. The national bibliography databases' prominent
status in resolution process is justified because these databases are a)
authoritative and b) exhaustive. The NB databases are based on deposit
collection, which contain a very large part of the published cultural
heritage in each country.

Local or publisher driven resolution services are much more limited in
this respect. Nevertheless, the ISBN registration document does make
room for resolution services provided by publishers (based on the ISBN
publisher ID) since such services may complement the one provided by the
national bibliography and the deposit collection.

Best regards,

Juha
--

Juha Hakala
Helsinki University Library
[email-masked]

Network Working Group                                       Juha Hakala
Internet-Draft                              Helsinki University Library
Category: Informational                                 30 January 2001
draft-ietf-hakala-nbn-02.txt
Expires: 30 July 2001

                Using National Bibliography Numbers as
                         Uniform Resource Names

Status of this Memo

This document is an Internet-Draft and is in full conformance with all
provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering Task
Force (IETF), its areas, and its working groups. Note that other groups
may also distribute working documents as Internet-Drafts.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference material
or to cite them other than as "work in progress."

To view the entire list of Internet-Draft Shadow Directories, see
http://www.ietf.org/shadow.html.

This Internet-Draft will expire on 30 July, 2001.

Abstract

This document discusses how national bibliography numbers (persistent
and unique identifiers assigned by the national libraries) can be
supported within the URN framework and the syntax for URNs defined in
RFC 2141 [Moats].Much of the discussion below is based on the ideas
expressed in RFC 2288 [Lynch]. Chapter 5 contains a URN namespace
registration request modelled according to the template in RFC 2611
[Daigle et al.].

1. Introduction

As part of the validation process for the development of URNs the IETF
working group agreed that it is important to demonstrate that the
current 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 [Lynch et. al.]
investigated the feasibility of using three identifiers (ISBN, ISSN and
SICI) as URNs.

This document will analyse the usage of national bibliography numbers
(NBNs) as URNs. The need to extend analysis to new identifier systems
was briefly discussed in RFC 2288 as well, with the following summary:
"The issues involved in supporting those additional identifiers are
anticipated to be broadly similar to those involved in supporting ISBNs,
ISSNs, and SICIs".

A registration request for acquiring a Namespace Identifier (NID) "NBN"
for national bibliography numbers has been written by the National
Library of Finland on the request of the Conference of Directors of
National Libraries (CDNL) and the Conference of the European National
Librarians (CENL). The request is included in chapter 5 of this text.

The document at hand is part of a global co-operation of the national
libraries to foster identification of electronic documents in general
and utilisation of URNs in particular. Some national libraries,
including the national libraries of Finland, Norway and Sweden, are
already assigning NBN-based URNs for electronic resources.

We have used the URN Namespace Identifier "NBN" for the national
bibliographic numbers in examples below.

2. Identification vs. Resolution

As a rule the national bibliography numbers identify finite, manageably-
sized objects, but these objects may still be large enough that
resolution to a hierarchical system is appropriate.

The materials identified by a national bibliography number may exist
only in printed or other physical form, not electronically. The best
that a resolver will be able to offer in this case is bibliographic data
from a national bibliography database, including information about where
the physical resource is stored in a national library's holdings.

The URN Framework provides resolution services that may be used to
describe any differences between the resource identified by a URN and
the resource that would be returned as a result of resolving that URN.
However, NBNs will be used for instance to identify resources in digital
Web archives created by harvester robot applications. In this case, NBN
will identify exactly the resource the user expects to see.

3. National bibliography numbers

3.1 Overview

National Bibliography Number (NBN) is a generic name referring to a
group of identifier systems utilised by the national libraries and only
by them for identification of deposited publications which lack an
identifier, or to descriptive metadata (cataloguing) that describes the
resources. In many countries legal (or voluntary) deposit is being
extended to electronic publications.

Each national library uses its own NBN strings independently of other
national libraries; there is no global authority which controls them.
For this reason NBNs are unique only on national level. When used as
URNs, NBN strings must be augmented with a controlled prefix such as
country code. These prefixes guarantee uniqueness of the NBN-based URNs
on the global scale.

NBNs have traditionally been given to documents that do not have a
publisher-assigned identifier, but are catalogued to the national
bibliography. NBNs can be seen as a fall-back mechanism: if no other,
better established identifier such as ISBN can be given, an NBN is
assigned. In principle, NBN usage enables identification of any Internet
document. Local policies may limit the NBN usage to a much smaller
subset of documents.

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 documents. At least national libraries
of Sweden and Finland are harvesting and archiving domestic Web
documents (and a number of other libraries plan to start this activity),
and long-time preservation of these materials requires persistent and
unique identification. NBNs can be and are in fact already used as
internal identifiers in these Web archives.

Both syntax and scope of NBNs can be decided by each national library
independently. Typically, an NBN consist of one or more letters and/or
digits. This simple syntax makes NBNs infinitely extensible and very
suitable for e.g. naming of the Web documents. For instance the
application used by the national library of Finland for Web harvesting
creates NBNs which are based on the MD5 checksum of the archived
resource.

3.2 F-code

F-code is the NBN used by the National Library of Finland.

F-codes have been used since early 20th century to identify catalogue
cards and later MARC records in the national bibliography. In 1998 the
national library decided to enable the Finnish authors and publishers to
assign F-codes to their Internet documents, if these documents do not
qualify for other identifiers such as ISBN. F-codes, embedded into URNs,
can be fetched from the URN generator (http://www.lib.helsinki.fi/cgi-
bin/urn.pl) developed in co-operation between the national library of
Finland and the Lund University library, NETLAB unit. Attached to the
generator there is a user guide (http://www.lib.helsinki.fi/meta/URN-
opas.html; only in Finnish), which tells the users how to use URNs.

F-codes are also used within the Web harvesting and archiving software
(http://www.csc.fi/sovellus/nedlib/), which has been built for the
Networked European Deposit Library (NEDLIB) project (see
http://www.kb.nl/nedlib). NEDLIB harvester calculates MD5 checksum for
each archived resource, and then builds an NBN-based URN from the
checksum. The URN serves then as a unique identifier to the archived
resource. Traditional identifiers can not be used for this purpose,
since there may for instance be several variants of a book which (quite
rightly so) all have the same ISBN. Moreover, identifiers embedded into
a document do not necessarily belong to the document itself; thus the
Web archiving application can not trust the identifiers embedded into
the body of the document.

The F-code built by the URN generator consist of:

Prefix (for example fe)
Year (YYYY; for example 1999)
Number (for example 1055)

The generator also adds namespace identifier "NBN" and ISO 3166 country
code. Thus a URN based on F-code would in this case be for instance
urn:nbn:fi-fe19991055.

URNs created by the Web archiving application have similar overall
structure, except that prefix (which may be defined by the operator) is
fea and year is not used. An example: urn:nbn:fi-fea-
5c5875e6e49ae649cad63e5ee4f6c346.

F-codes never need any special encoding when used as URNs, since they
consist of alphanumeric codes only (0-9, a-z). This is often the case
for other national libraries' NBN systems as well.

3.3 Encoding Considerations and Lexical Equivalence

Embedding NBNs within the URN framework usually presents no particular
encoding problems, since all of the characters that can appear in
commonly used NBN systems can be expressed in special encoding, as
described in RFC 2141 [MOATS].

When an NBN is used as a URN, the namespace specific string will consist
of three parts: prefix, consisting of either a two-letter ISO 3166
country code or other registered string, delimiting character which is
either hyphen (-) or colon (:), and NBN string assigned by the national
library. Delimiting characters are not lexically equivalent.

Hyphen is always used for separating the prefix and the NBN string.

Colon is used as the delimiting character if and only if a country code
-based NBN namespace is split further in smaller sub-namespaces. If
there are several national libraries in one country, these libraries can
split their national namespace into smaller parts using this method.

A national library may also assign a trusted organisation(s) its own
sub-namespace. For instance, the national library of Finland has given
Statistics Finland (http://www.stat.fi/index_en.html) a sub-namespace
"st" (e.g. urn:nbn:fi:st:). The Finnish Council of State
(http://www.vn.fi/vn/english/index.htm) will use sub-namespace "vn"
(e.g. urn:nbn:fi:vn).

Non-ISO 3166 -prefixes, if used, must be registered on the global level.
The Library of Congress will maintain the central register of reserved
codes. This register will be available to the national libraries and
other users in the Web.

Sub-namespace codes beneath a country-code -based namespace need to be
registered on the national level by the national library which assigned
the code. The national register must be available in the Web and should
also be linked to the global register maintained by the Library of
Congress.

Two-letter codes may not be used as non-ISO prefixes, since all such
codes are reserved for existing and possible future ISO country codes.
If there are several national libraries in one country who use the same
prefix - for instance, a country code -, they need to agree on how to
split the namespace between them.

Models:
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>

Examples:
URN:NBN:fi-fe19981001 (A "real" URN assigned by the National Library of
Finland).

3.4 Resolution of NBN-based URNs

The (usually) country code -based prefix part of the URN namespace
specific string will provide a guide to where to find a resolution
service, and the NBN register will identify the assigning agency. Once
the NBN-based URN resolution is in global usage, the number of prefixes
will slowly approach and may eventually exceed the number of national
libraries.

If NBN assignment for a given country is limited to the national
bibliography database, then all NBN-based URNs for that country will be
resolved there. In one model these databases contain detailed resource
descriptions including URLs, which will point both to the copy of the
document in the Internet and to the copy in the national library's
(legal) deposit collection. Due to the limitations in the usage of legal
deposit documents it is possible that the deposited electronic materials
can not be delivered in electronic form outside the premises of the
national library.

If it is possible for the authors and publishers to retrieve NBNs to Web
documents and there is no obligation to deposit thus identified
documents to the national library, URN resolution service is not
possible without a national Web index and archive, maintained by the
national library or other organisation(s). A Web index/archive will also
resolve machine-generated URNs to the archived Web documents.

3.5 Additional considerations

Guidelines adopted by each national library define when different
versions of a work should be assigned the same or differing NBNs. These
rules apply only if identifier assignment is done manually. If
identifiers are allocated programmatically, the only criteria that can
be used is that two documents which are identical on the bit level (have
the same MD5 checksum) are deemed identical and should receive the same
NBN. The likelihood of this happening to dissimilar documents is about
2^64, according to the RFC1321.

The rules governing the usage of NBNs are less strict than those
specifying the usage of ISBN or other, better established identifiers.
Since the NBNs have up to now been given only by the personnel
(cataloguers) working in the national libraries, the identifier
assignment has in practice been well co-ordinated.

A NBN-based URN will resolve to single instance of the work if
identifier assignment has been automatic. Given the nature of NBNs it is
also likely that different versions of the same work will receive
different NBNs even if the identifier is given manually.

4. Security Considerations

This document proposes means of encoding several existing bibliographic
identifiers within the URN framework. This document does not discuss
resolution except at a very generic level; thus questions of secure or
authenticated resolution mechanisms are out of scope.  It does not
address means of validating the integrity or authenticating the source
or provenance of URNs that contain bibliographic identifiers.  Issues
regarding intellectual property rights associated with objects
identified by the various bibliographic identifiers are also beyond the
scope of this document, as are questions about rights to the databases
that might be used to construct resolvers.

5. Namespace registration

URN Namespace ID Registration for the National Bibliography Number (NBN)

Namespace ID:

NBN

This Namespace ID has been in production use in demonstrator systems
since summer 1998; thousands of URNs from this namespace have already
been delivered in Finland, Sweden and Norway.

Registration Information:

Version: 3
Date: 2001-01-30
The first registration of the NID "NBN" was done via the URN WG in 1998.
The second, slightly edited registration request was done in 1999.

Declared registrant of the namespace:

Name: Juha Hakala
E-mail: [email-masked]
Affiliation: Helsinki University Library - The National Library of
Finland, Conference of European National Librarians (CENL) and
Conference of Directors of National Libraries (CDNL)
Address: P.O.Box 26, 00014 Helsinki University, Finland

Both CENL and CDNL made decisions to foster the usage of URNs during
1998. The latter organisation has set up a working group for this
purpose. One item in the common work plan is utilisation of national
bibliography numbers as URNs for identification of grey literature
published in the Internet. The NBN namespace will be available for free
for all national libraries in the world.

Declaration of syntactic structure:

The namespace specific string will consist of three parts:

prefix, consisting of either a two-letter ISO 3166 country code or other
registered string and sub-namespace codes,

delimiting characters (colon (:), or hyphen (-), and

NBN string assigned by the national library.

Colon is used as a delimiting character only within the prefix, between
ISO 3166 country code and sub-namespace code, which splits the national
namespace into smaller parts. This technique can be used when there are
several national libraries, which all need their own namespaces, or when
the national library allows trusted partners to set up their own sub-
namespaces within the national NBN namespace.

Dividing non-ISO 3166 -based namespaces further with sub-namespace codes
is not allowed.

Hyphen is used as a delimiting character between the prefix and the NBN
string. Within the NBN string, hyphen can be used for separating
different sections of the code 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,
will be created and made available via the Web. Contact information:
[email-masked].

All two-letter codes are reserved for existing and possible future ISO
country codes and may not be used as non-ISO prefixes.

Sub-namespace codes must be registered on the national level by the
national library which assigned the code. The register must be available
via the Web, and it should be accessible via the global registry set up
by the Library of Congress.

Models:

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:

A country code -based URN: URN:NBN:fi-fe19981001 (A URN assigned by the
National Library of Finland).

Relevant ancillary documentation:

National Bibliography Number (NBN) is a generic name referring to a
group of identifier systems used by the national libraries for
identification of deposited publications which lack an 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 no global authority which controls syntax of these
identifier systems.

Each national library can decide freely which resources will 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.

Some national libraries (Finland, Norway, Sweden) have established Web-
based URN generators, which enable authors and publishers to fetch NBN-
based URNs for their network documents.

Both syntax and scope of NBNs is decided by each national library
independently. Typically, a NBN consist of one or more letters and a
number.

Identifier uniqueness considerations:

NBN strings assigned by two national libraries may be identical. For
this reason usage of a controlled prefix in the namespace specific
string is obligatory in order to guarantee global uniqueness of NBN-
based URNs.

In the national level, libraries utilise different policies for
guaranteeing uniqueness. A national library may automate the delivery of
NBN-based URNs. In this case, the NBNs are assigned sequentially by a
program (URN generator).

Identifier persistence considerations:

Persistence of the NBNs as identifiers is guaranteed by the persistence
of national libraries and information systems, such as national
bibliographies, maintained by them. NBNs have been used for several
centuries for printed materials. NBN-based identification of electronic
documents is a recent practice, but it is likely to continue for a very
long time.

Process of identifier assignment:

Assignment of NBN-based URNs is always controlled on national level by
the national library / national libraries. The Conference of Directors
of National Librarians (CDNL) has established in 1999 a task force,
which will co-ordinate the URN usage in all national libraries.

National libraries may choose different strategies in assigning NBN-
based URNs. One option is assignment by the library personnel only. This
is done when the document is catalogued into the national bibliography.
Thus in this case the national bibliography database will serve as the
URN resolution service.

A national library may also set up a URN generator (generators), and
allow publishers and authors to retrieve NBN-based URNs from there. In
this case there is no guarantee that the identified resource will ever
be catalogued into the national bibliography, and URN resolution is
dependent on Web index/archive.

Process for identifier resolution:

URNs based on NBNs will be primarily resolved via the national
bibliography databases. In one model these databases contain detailed
resource descriptions including URLs, which will point both to the copy
of the document in the Internet and to the copy in the national
library's (legal) deposit collection. Due to the limitations in the
usage of legal deposit documents it is possible that the deposited
materials can not be delivered outside the premises of the national
library.

For those documents not catalogued into the national bibliography
database URN resolution may take place via national or international Web
indexes and/or archives. Nordic national libraries have established in
autumn 2000 a joint initiative called Nordic Web Archive (NWA), which
aims at creating a national Web archive into all Nordic countries.
Indexes to these archive systems will be able to act as URN resolution
services of any document which a) is or has been available via the Web,
and b) had an URN embedded into it.

Country code and additional sub-namespace information will provide a
guide to where to find appropriate resolution services. For instance, if
the country code is "fi", the primary resolution service is the national
bibliography database. Secondary resolution service is the Web archive.

Generally, there will be one or more resolution services specified for
each country, depending on the assignment policy and services of the
national library. If NBN assignment is limited to the national
bibliography database, then all NBN-based URNs for that country will be
resolved there. If the authors and publishers have been allowed to
retrieve NBNs to their Web resources, URN resolution services require a
national Web archive. If other organisations have been allowed to assign
NBNs, they may also set up their own URN resolution services.

Rules for Lexical Equivalence:

None in the global level. Any national library may provide its own
rules, on the basis of its NBN syntax.

Conformance with URN Syntax:

All NBNs we know of are ASCII strings consisting of letters (a-z) and
numbers (0-9). If NBN contains characters that are reserved in the URN
syntax, this data must be presented in hex encoded form as defined in
RFC2141. A national library may limit the full scope of its NBN strings
in URN usage in such a way that there are no reserved characters in the
URN namespace specific strings.

Validation mechanism:

None specified on the global level. A national library may use NBNs,
which contain a checksum and can therefore be validated, but this is for
the time being not a common practice.

Scope:

Global.

6. References

[Daigle et al.]: Daigle, L., van Gulik, D., Iannella, R. & Faltstrom,
P.: URN Namespace Definition Mechanisms, RFC2611, June 1999.
[Lynch] Lynch, C., Using Existing Bibliographic Identifiers as Uniform
Resource Names, RFC 2288, February 1998
[Moats] Moats, R., "URN Syntax", RFC 2141, May 1997.

7. Authors' Address

   Juha Hakala
   Helsinki University Library - The National Library of Finland
   P.O. Box 26
   FIN-00014 Helsinki University
   FINLAND

   E-mail: [email-masked]

8.  Full Copyright Statement

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---

From: Rob Cameron <[email-masked]>
Date: Wed, 31 Jan 2001 07:17:21 -0800

Juha,

With respect to the NBN document, I have one immediate concern
that you may wish to address in regard to the Rules for Lexical
Equivalence.   Just as you state that x and X are equivalent
in the ISBN document (with the implication that X is canonical)
I believe that you should make a similar statement with respect
to the country code component of an NBN.  Are "FI", "fi", "Fi"
and "fI" all legal and equivalent?  Personally, I think it's
best to stick with ISO 3166 precisely and require "FI".

This problem is an immediate concern to us in our implementation
of the NBN domain under the bibp: scheme as well.  Even if you do
not wish to change the document, I would like to know your
thoughts on this.  We want to make our bibp:NBN services
interoperate with any urn:NBN services that are developed.

Are there any urn:NBN servers that are available at this time?
We would appreciate the opportunity to direct NBN requests
to them; we would also provide feedback on any interoperability
concerns that arise.

On a general note, thanks for considering and responding on
my point with respect to resolution models.  Our work with the
bibp: scheme will continue to pursue the decentralized model,
but I agree that there is no need to refer to this in the
urn:ISBN document.

Please forgive me if my enthusiasm for our current work
overflows sometimes into the realm of what some might call
'advertizing.'  Whereas the pessism of many with respect
to URN work is based partly on doubts about whether DDDS
resolution services will ever be deployed, we are excited
by the fact that the resolution technology we require is
already widely deployed world-wide.  We also think our model
is the Right Thing for future bibliographic services: a
decentralized model that gives local libraries precedence
over publishers and global services and gives users
ultimate control to set their own bibliographic service
providers.