RFC 3188

RFC 3188: Using National Bibliography Numbers as Uniform Resource Names 🎀

okay bestie, let's start with the title block 🧚. This is RFC 3188, and it's called "Using National Bibliography Numbers as Uniform Resource Names." J. Hakala from the Helsinki University Library wrote it. It's Informational, dated October 2001. It doesn't obsolete or update any other RFC, since the title block doesn't list any. 💖

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Status of this Memo 📋

this memo is just giving info to the Internet community, so it isn't a standard of any kind 🙈 distribution is unlimited, so share it with everyone 💅

Copyright Notice ⚖️

Copyright (C) The Internet Society (2001). All Rights Reserved.

Abstract ✨

this doc is about how national bibliography numbers (persistent and unique identifiers assigned by the national libraries) can work inside the URN (Uniform Resource Names) framework and the URN syntax defined in RFC 2141 🦋 a lot of the discussion is built on the ideas from RFC 2288, so that one's a must-read 📚

1. Introduction 🌸

okay so the IETF working group agreed that it's really important to show that the current URN syntax proposal can handle identifiers that already exist in well-established namespaces 🫶 that's part of validating URNs. one big infrastructure for naming and managing things comes from the bibliographic community. bibliographic identifiers act as names for objects that exist in print and, more and more, in electronic formats 📖 RFC 2288 [Lynch] looked into whether three identifiers (ISBN, ISSN and SICI) could be used as URNs 🔍

this document is going to analyse how national bibliography numbers (NBNs) can be used as URNs 🧠 RFC 2288 also brought up the need to look at new identifier systems, and it gave this summary: "The issues involved in supporting those additional identifiers are anticipated to be broadly similar to those involved in supporting ISBNs, ISSNs, and SICIs". ✨

the National Library of Finland wrote a registration request for the Namespace Identifier (NID) "NBN" for national bibliography numbers 🇫🇮 they did it at the request of the Conference of Directors of National Libraries (CDNL) and the Conference of the European National Librarians (CENL). Chapter 5 has a URN namespace registration request that follows the template in RFC 2611 📝

this document is part of a global co-operation between national libraries to help identify electronic documents in general, and to get URNs used in particular 🌍 some national libraries, including the ones in Finland, Norway and Sweden, are already assigning NBN-based URNs for electronic resources 🎉

we've used the URN Namespace Identifier "NBN" for the national bibliographic numbers in the examples below 💜

2. Identification vs. Resolution 🔎

as a rule, national bibliography numbers identify finite, manageably-sized objects 💅 but those objects can still be big enough that resolving them to a hierarchical system makes sense 🌳

the materials that a national bibliography number identifies may exist only in print or some other physical form, not electronically 📚 in that case, the best a resolver can offer is bibliographic data from a national bibliography database, including info about where the physical resource is kept in a national library's holdings 🏛️

the URN Framework gives you resolution services that can be used to describe any differences between the resource a URN identifies and the resource that comes back when you resolve that URN 🧩 but NBNs will be used, for example, to identify resources in digital Web archives made by harvester robot applications 🤖 in that case, the NBN identifies exactly the resource the user expects to see, which is so iconic 🙌

3. National bibliography numbers 📚

3.1 Overview 🦋

okay so "National Bibliography Number (NBN)" is a generic name for a group of identifier systems. the national libraries use them, and only the national libraries, to identify deposited publications that don't have an identifier yet 📥 they're also used for descriptive metadata (cataloging) that describes the resources. in lots of countries, legal (or voluntary) deposit is being extended to electronic publications 💻

every national library uses its own NBN strings separately from the other national libraries, and there's no global authority that controls them 🌐 because of that, NBNs are unique only at the national level 🫣 when NBNs are used as URNs, the NBN strings need to be augmented with a controlled prefix, such as a country code. those prefixes are what guarantee that NBN-based URNs are unique on a global scale 🌏✨

NBNs have traditionally been given to documents that don't have a publisher-assigned identifier but are cataloged in the national bibliography 📖 they can be seen as a fall-back mechanism. if no other, better established identifier such as ISBN can be given, then an NBN is assigned 🪂 in principle, NBN usage makes it possible to identify any Internet document, though local policies may limit NBN usage to a much smaller subset of documents 🎯

some national libraries (e.g., Finland, Norway, Sweden) have set up Web-based URN generators, so authors and publishers can get NBN-based URNs for their network documents 🖥️ at least the national libraries of Sweden and Finland are harvesting and archiving domestic Web documents, and a number of other libraries plan to start doing this too 🕸️ long-term preservation of these materials needs persistent and unique identification, and NBNs can be used, and are in fact already used, as internal identifiers in these Web archives 🗂️💜

both the syntax and the scope of NBNs can be decided by each national library on its own 🙌 typically, an NBN is one or more letters and/or digits. this simple syntax makes NBNs infinitely extensible and very suitable for things like naming Web documents 🧁 for example, the application the Finnish national library uses for Web harvesting creates NBNs based on the MD5 checksum of the archived resource 🔐

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⚠️ that's the end of part 1! Sections 3.2 and 3.3 are coming up next, so stay tuned 🫶💖

3.4 Resolution of NBN-based URNs 🗺️

okay so the (usually) country code-based prefix part of the URN namespace specific string is basically a little map 💖 pointing you to where a resolution service lives, and the NBN register is what tells you which agency did the assigning. once NBN-based URN resolution is in global usage, the number of prefixes will slowly approach and may eventually exceed the number of national libraries. bestie that is a LOT of prefixes 😭

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 🔗, and those URLs point both to the copy of the document on the Internet and to the copy in the national library's (legal) deposit collection. ngl the plot twist is that, 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, then 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 only apply 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 RFC 1321 🧮

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

A NBN-based URN will resolve to a 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 🔐

okay this one is SERIOUS bestie, so pay attention 👑 This document proposes means of encoding several existing bibliographic identifiers within the URN framework. It does not discuss resolution except at a very generic level, so questions of secure or authenticated resolution mechanisms are out of scope. It also 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. not this doc going there 🙅‍♀️💀

5. Namespace registration ✨

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

Okay so bestie, the NBN namespace 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 🇫🇮🇸🇪🇳🇴 It's giving proven track record, periodt 💅

Namespace ID:

NBN

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: juha.hakala@helsinki.fi
• 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 🌈 Main character energy for sure 👑

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.

Okay, the colon is used as a delimiting character only within the prefix, between the ISO 3166 country code and the sub-namespace code 💜 It 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: nbn.register@loc.gov.us 📮

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 has 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 🫶

At 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 cannot 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 in all Nordic countries. Indexes to these archive systems will be able to act as URN resolution services for any document which a) is or has been available via the Web, and b) had a 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. The 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 at 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 an NBN contains characters that are reserved in the URN syntax, this data MUST be presented in hex encoded form as defined in RFC 2141. 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 ✨

Wait, I need to correct the last part: the original says "must", not MUST, so I'm keeping it lowercase here as written:

If an NBN contains characters that are reserved in the URN syntax, this data must be presented in hex encoded form as defined in RFC 2141. 🦋

Validation mechanism 🔍

None specified at 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.

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6. References 📚

[Daigle] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, "URN Namespace Definition Mechanisms", RFC 2611, June 1999.

[Lynch] Lynch, C., Preston, C. and R. Daniel, "Using Existing Bibliographic Identifiers as Uniform Resource Names", RFC 2288, February 1998.

[Moats] Moats, R., "URN Syntax", RFC 2141, May 1997.

7. Author's Address 🦋

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

EMail: juha.hakala@helsinki.fi

8. Full Copyright Statement 💜

Copyright (C) The Internet Society (2001). All Rights Reserved.

This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English 🌈

The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns 💖

This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE 😭

Acknowledgement 🫶

Funding for the RFC Editor function is currently provided by the Internet Society ✨