RFC 3044

Using The ISSN (International Serial Standard Number) as URN (Uniform Resource Names) within an ISSN-URN Namespace

📅 published January 2001, from ietf

RFC 3044: Using The ISSN (International Serial Standard Number) as URN (Uniform Resource Names) within an ISSN-URN Namespace 🎀

  • Network Working Group, Request for Comments: 3044 🧚
  • Author: S. Rozenfeld, ISSN International Centre 💅
  • Category: Informational 🌸
  • Date: January 2001 ✨
  • Obsoletes/Updates: the title block doesn't list anything this RFC obsoletes or updates 🦋

Status of this Memo 💜

okay so this memo is giving "for information only" 💅 It provides information for the Internet community, but it does not specify an Internet standard of any kind. Distribution of this memo is unlimited 🫶

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

Abstract 🔥

okay bestie, so the ISSN (International Standard Serial Number) is this super persistent number that's used to uniquely identify serials, and the bibliographic world is OBSESSED with it 😭 This doc shows how the ISSN can be supported inside the URN framework as its own specific URN namespace identifier 🦋

The ISSN International Centre (ISSN-IC) built an ISSN URN resolution system that uses the ISSN as a Uniform Resource Name inside an ISN URN Namespace. It's running as a demonstrator so they can check every requirement needed to deploy it in a real operational environment 👑

This whole thing builds on concepts and proposals from a few other IETF RFCs that focus on using "recognised" existing numbering systems inside the URN framework: RFC 2248, RFC 2141, and RFC 2611 💖

Table of Contents 🧚

1. Introduction ..................................................  2
2. The ISSN system ...............................................  3
  2.1 The ISSN code ..............................................  3
  2.2  Construction of ISSN ......................................  3
  2.3 The ISSN Bibliographic record ..............................  4
  2.4 The ISSN Network ...........................................  4
  2.5 The ISSN Register ..........................................  5
3. The ISSN and URN ..............................................  5
  3.1 compatibility ..............................................  5
  3.2 identification and access ..................................  7
4  Resolution ....................................................  7
  4.1 Overview of the ISSN URN Resolution system .................  8
  4.2 Global Resolution ..........................................  9
5. Registration of an ISSN URN Namespace ......................... 10
6. Security Considersations ...................................... 13
7. References .................................................... 13
8. Contact information and useful links .......................... 14
9. Full Copyright Statement ...................................... 15

1. Introduction 🌸

okay so the ISSN International Centre spent 1999-2000 building a URN implementation that takes advantage of how well the ISSN and the URN work together functionally 🙈

Their current implementation at the ISSN-IC is based on IETF RFCs about URNs, and it includes a centralised resolution system. That system lets you go straight to electronic resources by using ISSN identifiers as Uniform Resource Names inside an ISSN URN Namespace 💅

It basically proves that the URN can pull in existing identifiers from well established identification schemes that the bibliographic community already uses. Iconic behaviour 👑

BUT (and this is a big but 😭) to roll this demo out to a wider operational system, you need a responsible body or infrastructure to assign namespaces and manage an RDS/NAPTR global resolution framework. The idea is that "serials" covers all forms of serials, whether they're published in print or as electronic resources 📚

Since this document includes a Registration form for an ISSN URN Namespace, that form also repeats some paragraphs that already appear in other parts of this document 🎀

All figures and descriptions in this document are dated 13 July 2000. 🙈

2. The ISSN system 🦋

The ISSN system came out of a joint UNESCO and ICSU-AB working group on bibliographic descriptions. That group was set up in 1967 to build a world registry of serial titles that are currently issued, stored or archived ✨

Today the ISSN system is defined by an International standard, ISO 3297, and it relies on two main data elements 💖

The first is the International Standard Serial Number, which is a unique identifier for one specific serial publication.

The second is the key-title, which is a unique name given to a serial. It's inseparably linked with its ISSN 🫶

On top of those two, the whole thing sits on a well established framework: the ISSN International network 🌈

2.1 The ISSN code 💜

The ISSN (International Standard Serials Number) is defined in ISO standard 3297:1998 as a code for uniquely identifying serials 🧚

The standard says that each ISSN is a unique identifier for one specific serial publication. ISSNs apply to the entire population of serials, whether they're past, present, or going to be published in the foreseeable future, no matter what medium they're on 🔥

Serials include periodicals, newspapers, and annuals (like reports, yearbooks, directories, and so on), plus the journals, series, memoirs, proceedings, transactions, etc. of societies 📚

Today ISSNs are assigned to databases and electronic serial resources. Extending the scope to continuing resources is still being discussed 👀

2.2 Construction of ISSN 💅

The ISO 3297 standard says that an ISSN is made of eight digits, using Arabic numerals 0 to 9. The last digit is a check digit, and sometimes it's an X instead 🌸

The ISSN doesn't have any internal meaningful elements that tell you the language, country, publisher [or medium.] 🙈

The check digit is always in the extreme right position. It's calculated on a modulus 11 basis with weights 8 to 2, and X stands in for 10 whenever 10 would show up as a check digit 🧮✨

Each ISSN is inseparably linked to "the key title." The key title is a form of the title that's built to avoid duplicates, so every key title is unique in the ISSN database, which is also called the ISSN Register. ISSNs and key titles are equivalent, since they both identify the same serial without any ambiguity 💖

When it's printed or displayed, the ISSN gets the ISSN prefix and a space in front of it. It appears as two groups of four digits separated by a hyphen 🎀

Examples:

examples  ISSN 0000-0019   ISSN 1560-1560

The ISSN International Centre constructs and distributes ISSNs to the National Centres, which handle assignment 🦋

2.3 The ISSN Bibliographic record 📚

Along with the ISSN and key-title, an ISSN bibliographic record holds about thirty bibliographic data elements. Those let you identify a serial unambiguously and securely 🔥

One thing that makes these records special is that they include other ISSNs in linking fields. That's how relationships between the serial and a set of other related serials already identified get established 🫶

To recognise and access serial resources in digital form, the ISSN format picked up some extra data elements 💜

  • A medium code, which indicates the medium of the given serial
  • A linking field that expresses relations between the different forms of "equivalent" serials on different media (from printed version to online, and from online to printed)
  • The location of an electronic resource: the URLs of a given resource

2.4 The ISSN network 🌈

The ISSN network is the operational structure, and its main functions are: 🧚

  • collecting the material that needs to be identified
  • assigning the ISSN and the key title to a serial for unambiguous identification
  • creating and editing bibliographic records in ISSN format
  • making the bibliographic records available

The network is made up of:

  • National Centres, 69 centres in total, which are responsible for identifying serials published in their respective countries. Records created by National Centres are sent to the ISSN-IC for validation and to update the ISSN Register 💅
  • The International Centre, which coordinates the network. It also acts as a National Centre for serials published by international institutions and by countries that don't have a National Centre. It collects and checks all bibliographic records so the ISSN Register gets updated in a consistent way. And it maintains the ISSN Register and makes it available 👑

2.5 The ISSN Register 🎀

The ISSN Register is a database controlled and maintained by the ISSN-IC. It holds 970 000 bibliographic records stored in ISSN-MARC format (a subset of USMARC format). Those records are available on different media: CD-ROM, DAT, and the Internet 💖

3. THE ISSN AND URN 🦋

3.1 ISSN compliance with URN requirements 🎀

okay so this is the part where the authors check whether an ISSN can actually work as a URN, bestie 💅 They went through a stack of earlier documents about how URNs are supposed to behave:

  • URN Syntax (RFC 2141, May 1997 - R. Moats)
  • Using Existing Bibliographic Identifiers as Uniform Resource Names (RFC 2288 February 1998 - C. Lynch, R. Daniel)
  • Functional Requirements for Uniform Resource Names (RFC 1737, December 1994 - K. Sollins, L. Masinter)
  • URN Namespace Definition Mechanisms (RFC 2611, June 1999 - L. Daigle, R. Iannella)
  • A URN Namespace for IETF Documents (RFC 2648, August 1999 - R. Moats)

Then they checked every functional requirement from RFC 1737 one by one, and ISSN passes all of them 😭🫶

Requirements for URNs' functional capabilities (from RFC 1737)

  • Global scope 🌍: a URN is a name with global scope that doesn't imply a location, so it means the same thing everywhere.
    • Applicable for ISSN ✅: according to ISO standard 3297, there are no limitations for serial resource identification.
  • Global uniqueness 🔑: the same URN is never given to two different resources.
    • Applicable for ISSN ✅: an ISSN is assigned to one and only one serial resource. Once it's assigned, it is never re-assigned.
  • Persistence ⏳: a URN's lifetime is permanent.
    • Applicable for ISSN ✅: every ISSN is registered in the ISSN Register database, which covers current serial resources as well as ceased ones.
  • Scalability 📈: URNs can be given to any resource that might conceivably be available on the network, for hundreds of years.
    • Applicable for ISSN ✅: more than 98500000 ISSN have been assigned so far.
  • Legacy support 🕰️: the scheme has to support existing legacy naming systems.
    • Applicable for ISSN ✅: by definition, the ISSN system is a legacy identification system for serial resources.
  • Independence 🦋: only a name issuing authority decides the conditions under which it will issue a name.
    • Applicable for ISSN ✅: that's just how the ISSN system is defined.
  • Resolution 🗺️: for URNs that have corresponding URLs, there must be some feasible mechanism to translate a URN into a URL.
    • Applicable for ISSN ✅: the ISSN-IC built an ISSN URN resolver that translates one given ISSN into one or several URLs.

On top of those basics, URNs also have rules about how they're written out as a string: single encoding, simple comparison, simple human transcribability, transport friendliness, machine consumption, and text recognition. ISSN slays these too 💖

  • Applicable to ISSN ✨: as defined in the ISO standard, the ISSN is a very simple, very short character string that fully responds to all of those requirements.

Honestly, considering what the ISSN is for, its framework, and the new ways people are identifying electronic serial resources, the authors can confidently say the ISSN fulfills every URN requirement they listed. Iconic behaviour 👑

Syntax requirements

Next up are the syntax requirements from RFC2141 for a URN namespace. An ISSN-based URN namespace is compliant with them, because it doesn't use any reserved characters 🌸

RFC 2288 (4.2 Encoding Considerations and Lexical Equivalence) also says:

There is no problem representing ISSN in the namespace - specific string of URNs since all characters valid in the ISSN are valid in the namespace-specific URN string, and %-encoding is never required.

So, example time 🧚

urn:ISSN:1046-8188

Supplementary comparison rules also make sense for the ISSN namespace: hyphens should be dropped before comparing, and any x should be normalised to uppercase. Small details, big vibes 💜

3.2 Identification and access

A URN's job is also to give you safe access to a resource's characteristics and to the resource itself 🦋 You can think of an ISSN bibliographic record as metadata, since it holds all sorts of information about the resource you're trying to identify, describe, locate, and/or access.

The ISSN is already widely used as an identification number for serial resources. And since the ISSN Network provides URLs for the resources it identifies, the ISSN is now also a tool for finding and accessing resources on the Internet. This works through an ISSN URN resolution system, and that's the glow-up we're talking about 💅✨

4. RESOLUTION 🔥

The authors studied a few more documents for the specs and requirements on URN resolution:

  • URI Resolution Services Necessary for URN Resolution (RFC 2483, January 1999 - M. Mealling)
  • Resolution of Uniform Resource Identifiers using the Domain Name System (RFC 2168 June 1997 - R. Daniel, M. Mealling )
  • Architectural Principles of Uniform Resource Name Resolution (RFC 2276, January 1998 - K. Sollins )

4.1. Overview of the ISSN URN Resolution system

Using ISSN as a Uniform Resource Name means there has to be some mapping mechanism, so you can reliably get to available resources from normal Internet tools like a standard web browser 🌈

From the technical side, this led the team to build the different pieces of software and services needed to make that happen 🛠️

The resolution software should be able to turn a given ISSN-URN into electronic locations:

  • location of the bibliographic description or metadata
  • location of the periodical itself (if it is in electronic form).

These electronic locations are written as URLs, and those URLs aren't guaranteed to stay put 😬 So the URLs stored for resolution have to be checked and updated so they still map correctly to their URNs.

The URLs in the database must be checked regularly for accuracy, and if anything changes, it has to be reported in the ISSN-URN resolver database.

The browser has to include the URN facility, which lets you express the location of a given resource as an ISSN. If standard browsers don't include the URN option, a "plug-in" is to be developed 🧩

So four types of developments were considered:

Design and implementation of a resolver 🧠

  • In a first step, a global centralised resolution system was developed and implemented on one resolution server at the ISSN International Centre.

It makes sure a given ISSN maps effectively to one or several URL(s), which means "multiple resolution" is built in through the design and implementation of an ISSN-URL mapping file.

  • Today, the main way to map ISSNs to URLs is to pull them out of ISSN registered records and store them in a separate file, structured specially for the resolution process. Other ways of getting URLs for bibliographic resources identified by ISSN are also being tested. Management data and attributes are linked to URLs so the resolver can recognise the objects it handles.

Design and implementation of an URL checker 🕵️

  • To keep an eye on persistence and accessibility for ISSN-URN, a robot called the "URL Watcher" was written to check the status of all URLs stored in the ISSN-URL mapping file. Broken or redirected URLs are detected and stored so resolution stays efficient.

Design and implementation of a browser plug-in 🔌

  • Existing browsers don't include the URN "protocol" functionality yet. People expect it to be implemented in the near future. A plug-in for Netscape communicator and MS-Explorer has been developed and is available.

This means you can type the ISSN, preceded by the string urn:ISSN:, straight into the browser's address box instead of typing out the URL. The result is the bibliographic record and/or the online resource being displayed. Clicking an ISSN on an HTML page gives the same result 💖

example: urn:ISSN:1560-1560

4.2 Global resolution 🌍

Since the ISSN system doesn't address a local environment (like a single library), and it's expected to link to other URNs (or other identification services) for serial-related resources at other levels of granularity, the current resolution implementation needs to evolve into a global resolution system 🚀

Resolution, and global resolution especially, is seen as a major issue for becoming an ISSN URN Namespace 👑

This is what RFC 2611, "URN Namespace Definition Mechanisms," says on the topic:

Process for identifier resolution:

If a namespace is intended to be accessible for global resolution, it must be registered in an RDS (Resolution Discovery System, see [RFC2276]) such as NAPTR. Resolution then proceeds according to standard URI resolution processes, and the mechanisms of the RDS.

The authors' current thinking on fitting an ISSN URN Namespace into such an RDS for global resolution is mainly based on ideas and proposals from these RFCs:

  • RFC 2276 for RDS architecture for global resolution,
  • RFC 2168 for the NAPTR DNS extension,

And from a technical point of view, the current resolution system is flexible enough to fit into an RDS/NAPTR resolution framework 🦋✨

5. Namespace registration ✨

okay bestie, this is the part where we register the namespace itself 🎀

Namespace ID: ISSN

Registration Information: Version 1, dated 2000-08-28 📅

Declared registrant of the namespace:

Name:         S. ROZENFELD (Mr.)
E-mail:       rozenfeld@issn.org
Affiliation:  ISSN International Centre
Address: 20, rue Bachaumont
                75002 PARIS
                     FRANCE

Declaration of syntactic structure 🧩

so the ISSN is built per ISO standard 3297, Information and documentation International Standard Serial Number(ISSN)-(1998). it's eight digits using Arabic numerals 0 to 9, except the last digit is a check digit and can sometimes be an X. the ISSN has no internal meaningful elements to identify language, country, or publisher, so it's giving pure, meaningless vibes 😌

the check digit is always in the extreme right position. it's calculated on a modulus 11 basis with weights 8 to 2, and we use X in place of 10 whenever 10 would show up as a check digit 🔢

each ISSN is inseparably linked to the serials title "the key title", which is a constructed form of the title so we don't get duplicates. every key title is unique inside the ISSN Data base. the ISSN and the key title are equivalent, because they both identify the same serial without any ambiguity 💜

when it's printed or displayed, the ISSN gets the ISSN prefix and a space, and shall appear as two groups of four digits separated by a hyphen ✨

so the structure looks like this:

NNNN-NNNC

where N is a Digit character [0..9]
      C is either a Digit character or letter "X" [0..9,X]
      C is the check character

an ISSN URN Namespace structure is conformant to URN syntax requirements (RFC 2141) 🦋

examples:

urn:ISSN:0259-000X
urn:ISSN:1560-1560

Relevant ancillary documentation 📚

  • ISO 3279 Information and documentation - International Standard Serial Number (ISSN)
  • The ISSN: an identifier for serials in digital form. Compatibility with the URN framework. (ISSN International Centre - January 1999)
  • The ISSN-URN project. (ISSN International Centre - October 1999)

Identifier uniqueness considerations 🔐

uniqueness is guaranteed by the ISSN definition, bestie. as defined in ISO 3279, each ISSN is a "unique" identifier for one specific serial publication.

a different ISSN gets assigned to each publication issued on different media 📀

and an ISSN is never re-assigned. ever. it's iconic 👑

Identifier persistence considerations 🌸

persistence of the ISSN is guaranteed by the maintenance and update of the ISSN Register by the ISSN Centres. even records for "ceased" publications still stay in the ISSN database, and links between serials in the same "family" are expressed with related ISSNs inside the records. this linking mechanism extends the current identifier persistence concept, which is so cool 🧚

Process of identifier assignment 🏭

the ISSN network has 68 National Centres plus the International Centre, and together they:

  • collect the material to be identified
  • check for identification all types of serials, including electronic serial resources
  • assign an ISSN to each different periodical
  • establish the bibliographic record
  • make the data available

the data (the bibliographic records) is centralised at the ISSN International Centre for global uniqueness checking. a given ISSN refers to one and only one form of the title, the key-title, which is a key element of the bibliographic record alongside the ISSN.

today the ISSN database contains more than 950 000 bibliographic records 🤯 and special attention is given to electronic publication resources, related metadata, and the way to access them 💻

Process for identifier resolution 🔎

as a first step, the ISSN International Centre developed a centralised ISSN-URN resolver with multiple resolution capabilities, which runs as a demonstrator.

in a second step, they expect the ISSN Namespace to be accessible for global resolution and to provide a set of resolution services compliant with the RDS/NAPTR proposals 🫶

Rules for Lexical Equivalence 🔤

the check digit if 'X' is case-sensitive. so if "x" is found, it must be translated into upper case. ⚠️

the hyphen between the 4th and the 5th digit can be omitted 🙈

Conformance with URN Syntax ✅

there are no characters reserved. zero drama 💅

Security Considerations ✨

because this namespace defines no additional reserved characters, it does not add any security consideration 🛡️

Validation mechanism: none specified today.

Scope: global 🌍

6. Security Considerations 🔒

security issues are discussed in section 5, so go check that out 💖

7. References 📖

  • [1] ISO 3279 Information and documentation - International Standard Serial Number (ISSN)
  • [2] The ISDS Manual - ISSN International Centre (Paris, 1983) (under revision)
  • [3] Moats, R., "URN Syntax", RFC 2141, May 1997.
  • [4] Sollins, K. and L. Masinter, "Functional Requirements for Uniform Resource Names", RFC 1737, December 1994.
  • [5] Lynch, C., Preston, C. and R. Daniel, "Using Existing Bibliographic Identifiers as Uniform Resource Names", RFC 2288, February 1998.
  • [6] Daniel, R. and M. Mealling, "Resolution of Uniform Resource Identifiers using the Domain Name System", RFC 2168, June 1997.
  • [7] Sollins, D., "Architectural Principles of Uniform Resource Name Resolution", RFC 2276, January 1998.
Slawek Rozenfeld (Mr.)
Head, Computer Section
ISSN International Centre
  20, rue Bachaumont
        750002 PARIS
              FRANCE

EMail: rozenfeld@issn.org
       issnic@issn.org

ISSN Web site  http://www.issn.org
ISSN-URN links http://www.issn.org/urn/

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

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