rfc3187.txt

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Network Working Group                                          J. Hakala
Request for Comments: 3187                   Helsinki University Library
Category: Informational                                     H. Walravens
                                           The International ISBN Agency
                                                            October 2001


              Using International Standard Book Numbers as
                         Uniform Resource Names

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

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

Abstract

   This document discusses how International Standard Book Numbers
   (ISBN) can be supported within the URN (Uniform Resource Names)
   framework and the syntax for URNs defined in RFC 2141.  Much of the
   discussion below is based on the ideas expressed in RFC 2288.

1. Introduction

   As part of the validation process for the development of URNs, the
   IETF URN 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 ISBNs as URNs in more detail than RFC 2288.

   A registration request for acquiring Namespace Identifier (NID)
   "ISBN" for ISBNs is included in chapter 5.









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   The document at hand is part of a global joint venture of the
   national libraries to foster identification of electronic documents
   in general and utilisation of URNs in particular.  The document was
   written as a co-operative project between the Helsinki University
   Library and The International ISBN Agency.

   We have used the URN Namespace Identifier "ISBN" for ISBNs in
   examples below.

2. Identification vs. Resolution

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

   The materials identified by an ISBN 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 the national library's holdings.

3. International Standard Book Numbers

3.1 Overview

   RFC 2288 [Lynch] describes the ISBN system in the following way:

      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 (actually, the last digit
      can be the letter "X" as well, as described below) which is
      divided into four variable length parts usually separated by
      hyphens when printed.  The parts are as follows (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.







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      The group and publisher number assignments are managed in such a
      way that the hyphens are not needed to parse the ISBN
      unambiguously into its constituent parts.  However, the ISBN is
      normally transmitted and displayed with hyphens to make it easy
      for human beings to recognize these parts without having to make
      reference to or have knowledge of the number assignments for group
      and publisher identifiers.

   Groups usually cover only one country, but occasionally a single
   group is used in several countries.  For instance, group "3" is
   utilised in Germany, Austria and German-speaking parts of
   Switzerland.  "976" is used in Caribbean community (Antigua, Bahamas,
   Barbados, Belize, Cayman Islands, Dominica, Grenada, Guyana, Jamaica,
   Montserrat, St. Kitts-Nevis, St. Lucia, St. Vincent and the
   Grenadines, Trinidad and Tobago, Virgin Islands (Br))and "982" in
   South Pacific (Cook Islands, Fiji, Kiribati, Marshall Islands, Nauru,
   Niue, Solomon Islands, Tokelau, Tonga, Tuvalu; Vanuatu, Western
   Samoa).  For each international group, the International ISBN Agency
   has assigned ranges of publisher identifiers to individual countries.
   These ranges are listed on the ISBN web site (http://www.isbn.spk-
   berlin.de/html/prefix.htm).  The group identifiers are listed at
   http://www.isbn.spk-berlin.de/html/prefix/allpref.htm.

   There are plans to extend the ISBN into 13 digits in order to make
   the system more suitable for identification of electronic monographs.
   So called Bookland ISBN will consist of a traditional ISBN preceded
   by the 978 or 979 EAN flag.

3.2 Encoding Considerations and Lexical Equivalence

   RFC 2288 [Lynch] says that:

      Embedding ISBNs within the URN framework presents no particular
      encoding problems, since all of the characters that can appear in
      an ISBN are 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 additional equivalence rules are
      appropriate.  Prior to comparing two ISBN URNs for equivalence, it
      is appropriate to remove all hyphens, and to convert any
      occurrences of the letter X to upper case.








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3.3 Resolution of ISBN-based URNs

   The existing ISBN structure is suitable for URN resolution purposes.
   The group identifier can assist in the resolver discovery process.
   For instance, the group identifier "951" means Finland.  In this
   case, the Finnish national bibliographic database will be able to
   resolve the URN either into bibliographic data or - if the resource
   is available in the Internet - to the document itself.

   If a group identifier does not identify a single country but a
   language area, there are two means for locating the correct national
   bibliography.  First, it is possible to define a cascade of URN
   resolution services - for instance, German national bibliography,
   Austrian national bibliography and Swiss national bibliography, in
   this order - into the DNS records describing the resolution service
   for ISBNs starting with "3".  Second, the publisher identifier ranges
   assigned by the International ISBN Agency could be defined into the
   DNS records.  This method is better than cascading, since the correct
   resolution service can be found immediately.

   In some exceptional cases - notably in the US and in UK, where
   international companies do a significant portion of publishing - the
   information provided by the group identifier may not always be fully
   reliable.  For instance, some monographs published in New York by
   international publishing companies may get an ISBN with the group
   identifier "3".  This is technically appropriate when the
   headquarters or one of the offices of the publisher is located in
   Germany.

   Information about such a book will not be available in the German
   national bibliography, but via the Library of Congress systems.
   Unfortunately, the appropriate national bibliography cannot be known
   to the resolver discovery service.

   As a fall back mechanism a large union catalogue, such as WorldCat
   maintained by OCLC (http://www.oclc.org ) could be used to complement
   the default services provided by national bibliographies.

   The problem described above may well be less severe than it looks.
   Some international publishers (Springer, for example) give the whole
   production to the national library of their home country as legal
   deposit, no matter which country the book was published.  Thus
   everything published by Springer in New York with group identifier
   "3" will be found from the German national bibliography.  On the
   other hand, when these companies give their home base also as a place
   of publication, the "home" national library requires the legal
   deposit.




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   Due to the intelligent structure of ISBN, group identifier or even
   the publisher identifier can be used as a "hint".  Technically, it is
   possible to incorporate into the common structure also URN resolution
   services maintained by publishers.  For instance, "951-0" is the
   unique ISBN publisher identifier of the largest publisher in Finland,
   Sanoma-WSOY.  If they launch their own URN resolution services,
   resolution requests for ISBNs starting with "951-0" will be directed
   to the publisher's server, and all other requests to the national
   bibliography.

3.4 Additional considerations

   The basic guidelines for assigning ISBNs to electronic resources are
   the following:

   *  Format/means of delivery is irrelevant to the decision whether a
      product needs an ISBN or not.  If the content meets the
      requirement, it gets an ISBN, no matter what the format of the
      delivery system.

   *  Each format of a digital publication should have a separate ISBN.

   The definition of a new edition is normally based on one of the two
   criteria:

   *  A change in the kind of packaging involved: the hard cover
      edition, the paperback edition and the library-binding edition
      would each get a separate ISBN.  The same applies to different
      formats of digital files.

   *  A change in the text, excluding packaging or minor changes such as
      correcting a spelling error.  Again, this criterion applies
      regardless of whether the publication is in printed or in digital
      form.

   Although these rules seem very clear, their interpretation may vary.
   As [Lynch] points out,

      The choice of whether to assign a new ISBN or to reuse an existing
      one when publishing a revised printing of an existing edition of a
      work or even a revised edition of a work is somewhat subjective.
      Practice varies from publisher to publisher (indeed, the
      distinction between a revised printing and a new edition is itself
      somewhat subjective).  The use of ISBNs within the URN framework
      simply reflects these existing practices.  Note that it is likely
      that an ISBN URN will often resolve to many instances of the work
      (many URLs).




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   Publishers have also in some occasions re-used the same ISBN for
   another book.  This reasonably rare kind of human error does not
   threaten or undermine the value of the ISBN system as a whole.
   Neither do they pose a serious threat to the URN resolution service
   based on ISBNs.  An error will only lead into the retrieval of two or
   more bibliographic records from a national bibliographic database.
   Based on the information in the records, a user can choose the
   correct record from the result set.

   Most national bibliographies and especially the Books in Print
   correct ISBN mistakes.  The systems then provide cross references
   ("incorrect ISBN -> correct ISBN").

   Further details on the process of assigning ISBNs can be found in
   section 5  (Namespace registration) below.

4. Security Considerations

   This document proposes means of encoding ISBNs within the URN
   framework. ISBN-based URN resolution service is depicted here only in
   a fairly generic level; thus questions of secure or authenticated
   resolution mechanisms are excluded.  It does not deal with means of
   validating the integrity or authenticating the source or provenance
   of URNs that contain ISBNs.  Issues regarding intellectual property