RFC 2288

Using Existing Bibliographic Identifiers as Uniform Resource Names

📅 published February 1998, from ietf

RFC 2288: Using Existing Bibliographic Identifiers as Uniform Resource Names 📚✨

okay bestie, this one is from February 1998 and it's an Informational doc, so it's sharing ideas and proving things can work, not setting a standard 🎀. The authors are C. Lynch (Coalition for Networked Information), C. Preston (Preston & Lynch), and R. Daniel (Los Alamos National Laboratory), and it's a Network Working Group doc. The header has no Obsoletes or Updates line, so it doesn't replace or change any other RFC 💅

Status of this Memo 🌸

this memo is giving info for the Internet community. it doesn't specify an Internet standard of any kind, and distribution of it is unlimited 🫶

Copyright (C) The Internet Society (1998). All Rights Reserved. 💜

Abstract 🦋

okay so a system for Uniform Resource Names (URNs) must be capable of supporting identifiers from the naming systems people already use everywhere, and that's the whole point 😭 this doc looks at how three major bibliographic identifiers (the ISBN, ISSN and SICI) can fit into the URN framework and the URN syntax that's currently proposed 🎀

1. Introduction ✨

the IETF working groups have been cooking, most recently the Uniform Resource Names working group, and they've finally landed a syntax for URNs 🔥 the functional requirements and overall framework are in RFC 1737 [Sollins & Masinter], and the URN syntax spec is RFC 2141 [Moats] 🧚

part of the validation process is proving that the current URN syntax can handle identifiers that already exist in well established namespaces 💅 the bibliographic community has a whole infrastructure for assigning and managing names, and bibliographic identifiers name things that exist in print and, more and more, in electronic formats 📖 this memo shows that three representative bibliographic identifiers can work inside the URN framework and syntax being proposed right now 🌈

just so we're clear, this doc does not claim to be the "official" standard way of turning these bibliographic identifiers into URNs. it only shows that it's feasible 🙈 it wasn't written in consultation with the standards bodies and maintenance agencies that run the existing bibliographic identifiers. any real Internet standard for encoding these as URNs will need to be built together with those responsible bodies and agencies 🫶

there are also open questions about managing and registering Namespace Identifiers (NIDs) for URNs. to illustrate things, we used the three NIDs "ISBN", "ISSN" and "SICI" for the three bibliographic identifiers in this doc. we think that's the most appropriate choice, but it's not the only one 🤔 the NIDs could be based on the standards body and standard number instead (for example, "US-ANSI-NISO-Z39.56-1997" rather than "SICI"). another option is to lump all bibliographic identifiers into one "BIBLIOGRAPHIC" namespace and use the namespace-specific string to say which identifier is being used. the final answer has to wait for the outcome of the namespace management discussions in the working group and the wider IETF community 🎀

for this doc we picked three major bibliographic identifiers, both national and international, to fit in the URN framework: the International Standard Book Number (ISBN) [ISO1], the International Standard Serials Number (ISSN) [NISO1,ISO2, ISO3], and the Serial Item and Contribution Identifier (SICI) [NISO2] 📚 an ISBN identifies a monograph (a book). an ISSN identifies serial publications (journals, newspapers) as a whole. a SICI adds onto the ISSN to identify individual issues of serial publications, or parts of those issues (like one article, or the table of contents of a particular issue) 💖 the ISBN and ISSN are defined in the United States by standards from the National Information Standards Organization (NISO), and there are matching international standards from the International Organization for Standardization (ISO). NISO is the ANSI-accredited standards body serving libraries, publishers and information services 🌸 the SICI code is defined by a NISO document in the United States and doesn't have a parallel international standards document right now 🙈

there are lots of other bibliographic identifiers in common use, like CODEN, numbers assigned by big bibliographic utilities such as OCLC and RLG, and national library numbers like the Library of Congress Control Number, and some are still being developed 📖 this doc doesn't talk about them, but many of them will also need support in the URN framework as it moves to large scale implementation. the issues involved are expected to be pretty similar to the ones for ISBNs, ISSNs, and SICIs 🦋

2. Identification vs. Resolution 🔍

this distinction is super important: there's the resource a URN identifies, and then there's what a URN resolver can reasonably return when it tries to resolve an identifier 💅 for example, the ISSN 0040-781X identifies the popular magazine "Time", all of it, every issue from the start of publication to the present 📰 resolving that identifier should not end up dumping the equivalent of hundreds of thousands of pages of text and photos onto the user's machine 😭 it's more reasonable for ISSNs to resolve to a navigational system, like an HTML-based search form, so the user can pick the issues or articles they want 🫶 ISBNs and SICIs, on the other hand, identify finite, manageably-sized objects, but those objects can still be big enough that resolving to a hierarchical system is the right move 🌳

also, the materials identified by an ISSN, ISBN or SICI may only exist in print or some other physical form, not electronically 📚 the best a resolver may be able to offer is info about where to get the physical resource, like library holdings or a bookstore or publisher order form 🛒 the URN Framework has resolution services that can describe any differences between the resource a URN identifies and the resource that gets returned when that URN is resolved ✨

3. International Standard Book Numbers 📖

3.1 Overview 🎀

an International Standard Book Number (ISBN) identifies an edition of a monographic work 💖 the ISBN is defined by the standard NISO/ANSI/ISO 2108:1992 [ISO1] 🔥

basically, an ISBN is a ten-digit number (the last digit can also be the letter "X", more on that below) and it's split into four variable length parts, usually separated by hyphens when printed 🧩 the parts go in this order:

  • a group identifier, which specifies a group of publishers based on national, geographic or some other criteria,
  • the publisher identifier,
  • the title identifier,
  • and a modulus 11 check digit, using X instead of 10.

the group and publisher number assignments are managed so that the hyphens aren't needed to parse the ISBN into its parts unambiguously 🌈 but the ISBN is normally sent and shown with hyphens so humans can spot the parts easily, without needing to know the number assignments for group and publisher identifiers 🫶

3.2 Encoding Considerations and Lexical Equivalence 💅

putting ISBNs into the URN framework has no real encoding problems, since every character that can show up in an ISBN is valid in the identifier segment of the URN ✨ %-encoding, as described in [MOATS], is never needed 🙅‍♀️

Example:

URN:ISBN:0-395-36341-1

for the ISBN namespace, some extra equivalence rules make sense. before comparing two ISBN URNs for equivalence, it's appropriate to remove all hyphens, and to convert any occurrences of the letter X to upper case 🔠

3.3 Additional considerations 🧠

the ISBN standard and related community implementation guidelines define when different versions of a work should get the same or different ISBNs 📚 but honestly, practice varies a bit by publisher, like whether paperbound and hardbound versions of the same work get different ISBNs, or electronic and printed versions do, or versions distinguished some other way (for example, published in the US and in Europe) 🌍 deciding whether to assign a new ISBN or reuse an existing one, when a revised printing or even a revised edition comes out, is kinda subjective too 😭 practice varies from publisher to publisher (and the line between a revised printing and a new edition is itself a bit subjective) 🙈 the use of ISBNs within the URN framework just reflects these existing practices 💖 also, an ISBN URN will often resolve to many instances of the work (many URLs) 🌸

4. International Standard Serials Numbers 📰

4.1 Overview 💜

International Standard Serials Numbers (ISSN) identify a work that's published on a continued basis in issues, so they identify the entire work, which is often open-ended if it's still being actively published 🔁 ISSNs are defined by the international standards ISO 3297:1986 [ISO2] and ISO/DIS 3297 [ISO3], and within the United States by NISO Z39.9-1992 [NISO1] 🇺🇸 the ISSN International Centre is in Paris and coordinates a network of regional centers 🗼 the National Serials Data Program within the Library of Congress is the US Center of that network 📚

ISSNs have the form NNNN-NNNN, where N is a digit, and the last digit may be an upper case X from the check character calculation 🔢 unlike ISBNs, the ISSN components don't have much structure, since blocks of numbers get handed out to regional centers and publishers 🎁

4.2 Encoding Considerations and Lexical Equivalence 🫶

again, there's no problem representing ISSNs in the namespace-specific string of URNs, because every character valid in an ISSN is valid in the namespace-specific URN string, and %-encoding is never required ✨

Example:

URN:ISSN:1046-8188

extra comparison rules are also appropriate for the ISSN namespace. just like with ISBNs, hyphens should be dropped before comparing, and occurrences of 'x' get normalized to uppercase 🔠💅

4.3 Additional Considerations ✨

okay so the ISSN standard and the community guidelines around it spell out when you get a brand new ISSN versus when you keep using the one you already have 📚 but ngl, bibliographic people don't all do this the same way. annuals and annual conference proceedings are the big drama 🙈 some places treat them as serials and use ISSNs, and other places treat them as monographs and use ISBNs.

Check this example, it's giving main character energy 🎀 SIGMOD Record volume 24 number 2 June 1995 contains the Proceedings of the 1995 ACM SIGMOD International Conference on Management of Data. If you subscribe to the journal (ISSN 0163-5808), it's just the June issue. But if you got that volume as the conference proceedings (a monograph), you'd use the ISBN 0-89791-731-6 to identify the work 📖

Publishers also don't agree on when a new ISSN should be assigned. Sometimes it's because a periodical changes its name (like Atlantic becoming Atlantic Monthly 🍸), and sometimes it's because a periodical comes out in both print and electronic versions (like The New York Times 🗞️). The use of ISSNs in URNs will reflect these judgments and practices 💅

5. Serial Item and Contribution Identifiers 🧚

5.1 Overview

okay now we're getting into SICI codes 🦋 the standard for Serial Item and Contribution Identifiers was recently revised a lot, and it's defined by NISO/ANSI Z39.56-1997 [NISO2]. The maintenance agency for SICI codes is the UnCover Corporation 🏢

SICI codes can identify an issue of a serial, or a specific contribution (like an article, or the table of contents) inside an issue 💖 and they're not assigned, they're constructed from info about the issue or the piece in question. so cute, right? 🥰

I'm not going to go through the whole syntax here, bestie. For all the details, check NISO/ANSI Z39.56-1997 [NISO2] 📚 but you do need an example and a quick tour of the main parts so you can see how a SICI relates to an ISSN and how it's different. Here's one: 0015-6914(19960101)157:1<62:KTSW>2.0.TX;2-F ✨

The first nine characters are the ISSN for the serial title 🌸 The second part, in parentheses, is the chronology info, which is the date the issue was published. In this example that's January 1, 1996 📅 The third part, 157:1, is the enumeration info (volume and number) for that issue 🔢 Those three pieces together make up the "item segment" of a SICI code. By adding chronology and/or enumeration to the ISSN, you can pin down a specific issue of the serial 🎯

The next segment, <62:KTSW>, identifies a particular contribution inside the issue. In this example it gives the starting page number and a title code made from the first characters of the title 🧠 If page numbers aren't appropriate, an identifier assigned to a contribution can be used in the contribution segment instead 🫶 The rest of the identifier is the control segment, which includes a check character. If you want the meaning of each field in that segment, the standard is the place to look 💜

5.2 Encoding Considerations and Lexical Equivalence

the character set for SICIs is meant to be email-transport-transparent, so it doesn't cause major problems 📧 BUT (and this is important, bestie 🚨) all printable excluded and reserved characters from the URN syntax are valid in the SICI character set and must be %-encoded.

Here's an example of a SICI for an issue of a journal 📰

URN:SICI:1046-8188(199501)13:1%3C%3E1.0.TX;2-F

And here's one for an article inside that same issue 📝

URN:SICI:1046-8188(199501)13:1%3C69:FTTHBI%3E2.0.TX;2-4

Equivalence rules for SICIs are not appropriate to define as part of the namespace, or to put into areas like cache management algorithms 🙅‍♀️ It's better to leave that to resolver systems, which try to work out whether two SICIs refer to the same content. So we don't propose any specific rules for equivalence testing through lexical manipulation 🌈

5.3 Additional Considerations

okay this part is a little messy, ngl 😭 since the serial is identified by an ISSN, some of the ambiguity in ISSN assignment carries over into SICI codes too 🫠 When an ISSN could refer to a serial that exists in several formats, the SICI has a qualifier that says which format it is (for example, print, microform, or electronic) 🖨️💻

SICI codes can be built from all kinds of sources: the actual issue of the serial, a citation, or a record from an abstracting service 📑 Because of that, they follow the principle of using all available information, so the same article might end up with more than one SICI [NISO2, Appendix D] 👯 For example, one code might be built with access to both chronology and enumeration (the date of issue plus volume, issue and page number), while another code is built only from enumeration info, with no chronology 🕰️

Systems that use SICI codes use complex matching algorithms to match codes built from incomplete information to codes built with all the relevant info 🧩 it's a whole thing, but it's the vibe 💅

6. Security Considerations 🔐

this part is serious, so let's get into it 🫡 This document proposes ways to encode several existing bibliographic identifiers within the URN framework. This document does not discuss resolution, so questions about secure or authenticated resolution mechanisms are out of scope. It also doesn't address ways to validate the integrity or authenticate the source or provenance of URNs that contain bibliographic identifiers. Issues about intellectual property rights for objects identified by these bibliographic identifiers are beyond the scope of this document too, and so are questions about rights to the databases that might be used to build resolvers ⚠️

7. References 📚

[ISO1] NISO/ANSI/ISO 2108:1992 Information and documentation
      -- International standard book number (ISBN)
[ISO2] ISO 3297:1986 Documentation -- International standard
      serial numbering (ISSN)
[ISO3] ISO/DIS 3297 Information and documentation --
      International standard serial numbering (ISSN) (Revision of ISO
      3297:1986)
[Moats] Moats, R., "URN Syntax", RFC 2141, May 1997.
[NISO 1] NISO/ANSI Z39.9-1992 International standard serial
      numbering (ISSN)
[NISO 2] NISO/ANSI Z39.56-1997 Serial Item and Contribution
      Identifier
[Sollins & Masinter] Sollins, K., and L. Masinter, "Functional
      Requirements for Uniform Resource Names", RFC 1737, December
      1994.

8. Authors' Addresses 💌

Clifford Lynch
Executive Director
Coalition for Networked Information
21 Dupont Circle
Washington, DC 20036

EMail: cliff@cni.org


Cecilia Preston
Preston & Lynch
PO Box 8310
Emeryville, CA 94662

EMail: cecilia@well.com


Ron Daniel Jr.
Advanced Computing Lab, MS B287
Los Alamos National Laboratory
Los Alamos, NM, 87545

EMail: rdaniel@acl.lanl.gov

Copyright (C) The Internet Society (1998). All Rights Reserved.

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