IETF URNbis WG                                               M. Huttunen
Internet-Draft                                                 J. Hakala
Obsoletes: 2288,3187 (if approved)       The National Library of Finland
Intended status: Standards Track                          A. Hoenes, Ed.
Expires: April 22, 2013                                           TR-Sys
                                                        October 19, 2012

  Using International Standard Book Numbers as Uniform Resource Names


   The International Standard Book Number, ISBN, is a widely used
   identifier for monographic publications.  Since 2001, the URN
   (Uniform Resource Name) namespace "ISBN" has been reserved for ISBNs.
   The namespace registration was performed in RFC 3187 and applied only
   to the ISBN as specified in the ISO Standard 2108-1992, now known as
   "ISBN-10".  To allow for further growth in use, the successor ISO
   Standard, ISO 2108:2005, has defined an expanded format for the ISBN,
   known as "ISBN-13".  This document defines how both of these ISBN
   standard versions can be supported within the URN framework.
   Moreover, additional query and fragment usage related information
   required by RFC 2141bis has been included.  An updated namespace
   registration conformant to RFC 3406bis is provided.  It describes how
   both the old and the new ISBN format can share the same namespace.

   This document replaces RFC 3187; it also obsoletes and moves to
   Historic status the predecessor thereof, RFC 2288.


   This draft is based on individual work started in 2008.  When the
   URNBIS working group was launched, revision of the ISBN namespace
   registration was included in its charter.

   Comments are welcome and should be directed to the
   mailing list or the authors.
   [[ RFC-Editor: this clause to be deleted before RFC publication ]]

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Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   This Internet-Draft will expire on April 22, 2013.

Copyright Notice

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   document authors.  All rights reserved.

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   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Conventions used in this document  . . . . . . . . . . . . . .  5
   3.  Fundamental Namespace and Community Considerations . . . . . .  5
     3.1.  The URN:ISBN Namespace . . . . . . . . . . . . . . . . . .  5
     3.2.  Community Considerations for ISBNs . . . . . . . . . . . .  5
   4.  International Standard Book Numbers  . . . . . . . . . . . . .  6
     4.1.  Overview / Namespace Considerations  . . . . . . . . . . .  6
       4.1.1.  ISBN-10 Structure  . . . . . . . . . . . . . . . . . .  6
       4.1.2.  ISBN-13 Structure  . . . . . . . . . . . . . . . . . .  7
       4.1.3.  Relation between ISBN-10 and ISBN-13 . . . . . . . . .  7
     4.2.  Encoding Considerations  . . . . . . . . . . . . . . . . .  8
     4.3.  Resolution of ISBN-based URNs  . . . . . . . . . . . . . .  8
       4.3.1.  General  . . . . . . . . . . . . . . . . . . . . . . .  8
       4.3.2.  Practical Aspects  . . . . . . . . . . . . . . . . . .  9
     4.4.  Additional Considerations  . . . . . . . . . . . . . . . . 12
   5.  URN Namespace Registration and Use . . . . . . . . . . . . . . 13
     5.1.  URN Namespace ID Registration for the International
           Standard Book Number (ISBN)  . . . . . . . . . . . . . . . 13
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 18
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 18
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 19
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 19
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 20
   Appendix A.  Draft Change Log  . . . . . . . . . . . . . . . . . . 21
     A.1.  draft-hakala-rfc3187bis-isbn-urn-00 to
           draft-ietf-urnbis-*-00 . . . . . . . . . . . . . . . . . . 21
     A.2.  draft-ietf-urnbis-rfc3187bis-isbn-urn-00 to -01  . . . . . 21
     A.3.  draft-ietf-urnbis-rfc3187bis-isbn-urn-01 to -02  . . . . . 21
     A.4.  draft-ietf-urnbis-rfc3187bis-isbn-urn-02 to -03  . . . . . 21

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1.  Introduction

   One of the basic permanent URI schemes (cf. RFC 3986 [RFC3986],
   [IANA-URI]) is 'URN' (Uniform Resource Name) as originally defined in
   RFC 2141 [RFC2141] and now being formally specified in RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn].  Any identifier, when used within
   the URN system, needs its own namespace.  At the time of this
   writing, there were over 45 registered URN namespaces (see
   [IANA-URN]), one of which belongs to ISBN, International Standard
   Book Number, as specified 2001 in RFC 3187 [RFC3187].

   Since 2007, there have been two variants of ISBN in use; an outdated
   one based on ISO 2108-1992 [ISO1] and a new one defined in ISO 2108-
   2005 [ISO2].  These versions shall subsequently be called "ISBN-10"
   and "ISBN-13", respectively.  If what is said in this document
   applies to both ISBN versions, the generic term "ISBN" is used.

   As part of the validation process for the development of URNs, the
   IETF URN working group agreed that it is important to demonstrate
   that a 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
   [RFC2288] investigated the feasibility of using three identifiers
   (ISBN, ISSN, and SICI -- see below) as URNs, with positive results;
   however, it did not formally register corresponding URN namespaces.
   This was in part due to the still evolving process to formalize
   criteria for namespace definition documents and registration,
   consolidated later in the IETF, first into RFC 2611 [RFC2611], then
   into RFC 3406 [RFC3406], and now given by RFC 3406bis

   URN Namespaces have subsequently been registered for both ISBN
   (International Standard Book Number) and ISSN (International Serial
   Standard Number) in RFCs 3187 [RFC3187] and 3044 [RFC3044],
   respectively, but not for SICI (Serial Item and Contribution
   Identifier), mainly due to the identifier's limited popularity.

   Guidelines for using ISBN-10s (based on ISO 2108:1992) as URNs and
   the original namespace registration have been published in RFC 3187
   [RFC3187].  The RFC at hand replaces RFC 3187; sections related to
   ISBN-13 have been added, all ISBN-10 information has been updated,
   and the namespace registration revised to make it compliant with both
   ISBN versions and the stipulations of RFC 3406bis

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2.  Conventions used in this document

   When spelled in all-capitals as in this paragraph, the key words
   "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document
   are to be interpreted as described in BCP 14 [RFC2119].

   "ISBN-10" refers to the original, 10-digit ISBN scheme specified in
   ISO 2108-1992 [ISO1].

   "ISBN-13" refers to the current, 13-digit ISBN scheme specified in
   ISO 2108-2005 [ISO2].

   "URN:ISBN" is used as a shorthand for "ISBN-based URN".

3.  Fundamental Namespace and Community Considerations

3.1.  The URN:ISBN Namespace

   ISBN is a well established standard identifier system for monographic
   publications.  Therefore, any useful and deployable method for
   identifying these entities for Internet-wide reference and making
   their metadata available on the Internet needs to be based on ISBNs.

3.2.  Community Considerations for ISBNs

   ISBNs are assigned under the auspices of the International ISBN
   Agency [ISBNORG] and national/regional ISBN agencies.  ISBN
   assignment is a well managed and understood process, but as in any
   process administered by humans, errors do take place.  If so, there
   are procedures in place for fixing the incorrect ISBNs.

   Books are finite objects, which may consist of (logical) component
   resources such as chapters or short stories / novellas.  Such
   component resources can get an ISBN if and only if they are for sale
   independently.  For example, a user could purchase either the entire
   short story collection, or just one short story.  Either way, he gets
   a file with the relevant content.  Logical components can also be
   represented in the physical structure of the document; for instance,
   chapters of a digital book may be encoded into its HTML structure.
   Then and only then an URI fragment can be attached to the URN:ISBN.
   The entire resource will be retrieved, but the fragment will be
   applied by the browser to take the user into the desired point within
   the document.  Please note that according to the ISBN standard, ISBN
   MUST be assigned to a single manifestation of the resource.  An ISBN
   given to the PDF version of the book cannot be reused to the EPUB 3

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   The ISBN standard does not allow augmentation of the ISBN itself with
   an identification of a physical component resource of a book.
   However, if a fragment part is added to a URI reference to an URN:
   ISBN, the namespace specific string is still the base ISBN only, and
   lexically, the URN with and without the URI fragment identifier are

   For the ISBN community, the use of URI fragment identifiers provides
   additional functionality that would not be easily available in any
   other way.  An ISBN-13 can be assigned to logical component
   resources, but this feature has not been used extensively.  URI
   fragment offers a light-weight (technically and administratively)
   solution to the users to pinpoint component resources within
   electronic manifestations of books, provided that these components
   have been encoded in an appropriate manner.

   The materials identified by an ISBN can exist only in printed or
   other physical form, not as digital resources accessible in the WEB;
   and even if an electronic book exists, its access rights may be
   limited.  ISBN-based URN resolution services are expected to support
   a wide variety of information services related to books.  Hence, when
   the identified manifestation of the book cannot be supplied, the
   applicable URN:ISBN resolver SHOULD supply descriptive and rights
   metadata about the relevant manifestation; the resolver MAY also
   provide links to other manifestations of the same work, or to related

   The next section presents an overview of the application of the URN:
   ISBN namespace and the principles, and systems used, for the
   resolution of ISBN-based URNs.

4.  International Standard Book Numbers

4.1.  Overview / Namespace Considerations

   An International Standard Book Number (ISBN) identifies a product
   form or edition of a monographic publication.  ISO 2108 requires that
   each product form (e.g. hardcover, paperback, PDF) has its own ISBN.

4.1.1.  ISBN-10 Structure

   The ISBN-10 is defined by the ISO Standard 2108-1992 [ISO1].  It is a
   ten-digit number (the last "digit" can be the letter "X" as well)
   that is divided into four variable-length parts usually separated by
   hyphens when printed.  Note that these hyphens can be removed; ISBNs
   with and without the hyphens are lexically equivalent.  The parts are
   as follows (in this order):

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   o  a group identifier that specifies a group of publishers, based on
      national scope, geographic scope, or some other criteria;

   o  the publisher identifier;

   o  the title identifier; and

   o  a modulo 11 check digit, using X instead of 10; the details of the
      calculation are specified in the ISO Standard [ISO1].

   ISBN-10s were assigned starting from the 1970s until the introduction
   of ISBN-13 in January 2007.

4.1.2.  ISBN-13 Structure

   ISBN-13 is defined by the ISO Standard 2108-2005 [ISO2].  The ISBN-13
   is a thirteen-digit number that is divided into five parts usually
   separated by hyphens when printed.  The first and the last part have
   a fixed lenght, but the other parts have variable length.  These
   parts are as follows (in this order):

   o  an ISBN-13 prefix element -- a 3-digit prefix specified by the
      International ISBN Agency; at the time of this writing, applicable
      values were 978 and 979; future versions of the standard may
      define additional values;

   o  a registration group element that specifies the registration
      group; it identifies the national, geographic, language, or other
      such grouping within which one or more ISBN Agencies operate;

   o  the registrant element;

   o  the publication element; and

   o  a modulo 10 check digit; the details of the calculation are
      specified in the ISO Standard [ISO2].

4.1.3.  Relation between ISBN-10 and ISBN-13

   The structural differences between the ISBN-10 and ISBN-13 are the
   prefix element (which does not exist in the ISBN-10) and the check
   digit calculation algorithm, which is modulo 11 in ISBN-10 and modulo
   10 in ISBN-13.

   Further, the terminology in ISBN-10 differs substantially from the
   terminology applied in ISBN-13.  In this document, ISBN-13
   terminology shall be used from now on; for a reader used to ISBN-10
   terminology, the following mapping may be useful:

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   o  ISBN-10 group identifier <-> ISBN-13 registration group element
      under prefix 978;

   o  ISBN-10 publisher identifier <-> ISBN-13 registrant element;

   o  ISBN-10 title identifier <-> ISBN-13 publication element.

   Any ISBN-10 can be converted to ISBN-13 form (and retrospective
   conversion is the recommended practice in ISO 2108:2005) by mapping
   it into the ISBN-13 prefix-978 range and recalculating the check
   digit.  Any application that processes ISBN-based URNs MUST be
   prepared to deal with both kinds of ISBNs, since instances of ISBN-10
   numbers will persist that cannot be converted to the new form (e.g.,
   ISBNs imprinted in books).  ISBN-13s using prefix element 979 cannot
   be converted back to ISBN-10, since under this prefix, ISBNs group
   identifiers will be re-assigned from scratch.  New books may still
   have ISBN-10 alongside ISBN-13 for practical reasons, but only as
   long as the prefix element in ISBN-13 is 978.

4.2.  Encoding Considerations

   Embedding ISBNs within the URN framework does not present encoding
   problems, since all of the characters that can appear in an ISBN are
   valid in the namespace-specific string (NSS) part of the URN.
   Percent-encoding, as described in RFC 2141bis
   [I-D.ietf-urnbis-rfc2141bis-urn], is never needed.  In order to
   improve readability of the NSS, hyphens MAY be used.

      Example 1: URN:ISBN:978-0-395-36341-6

      Example 2: URN:ISBN:951-0-18435-7

      Example 3: URN:ISBN:951-20-6541-X

      Example 3: URN:ISBN:951206541X

4.3.  Resolution of ISBN-based URNs

4.3.1.  General

   For URN resolution purposes, all elements except the check digit (0-9
   for ISBN-13, and 0-9 or X for legacy ISBN-10) must be taken into
   account.  The registration group and registrant element 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 humans to recognize these elements without having to make
   reference to or have knowledge of the number assignments for

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   registration group and registrant elements.  In ISBN-10, registration
   group element codes such as 91 for Sweden were unique.  In ISBN-13,
   only the combinations of prefix and registration group elements are
   guaranteed to be unique. 978-951 and 978-952 both mean Finland, but
   979-951 and 979-952 almost certainly will not (once they will be
   assigned in the future); at the time of this writing, registration
   group element(s) for Finland are not yet known for ISBNs starting
   with 979.

   The Finnish URN registry is maintained by the national library.  The
   service is capable of resolving ISBN-based URNs.  URNs starting with
   URN:ISBN:978-951 or URN:ISBN:978-952 are mapped into appropriate URL
   addresses in a table maintained within the registry.  Applications,
   such as the national bibliography or the open archive of a
   university, can use the URN as the persistent address of the
   resource.  There is just one place (the URN registry) where the
   address is mapped to one or more physical locations.

   ISBN-13 prefix / registration group element combinations (and the
   corresponding ISBN-10 registration group identifiers, if any) usually
   designate a country, but occasionally a single combination / ISBN-10
   group identifier is used to indicate a language area.  For instance,
   "978-3" (or "3" in ISBN-10) is utilised in Germany, Austria, and the
   German speaking parts of Switzerland.  As of this writing, there are
   two regional registration groups: "978-976" is used in the Caribbean
   community and "978-982" in the South Pacific (see [ISBN_PREFIX]).

   Note that the prefix and registration group element combination
   "979-3" has not yet been assigned.  There is no intention to allocate
   the registration group elements in the same way as was done with

   The registrant element may or may not be used for resolution
   purposes, depending on whether individual publishers have set up
   their resolution services.

   The publication element shall enable targeting the individual

4.3.2.  Practical Aspects

   Due to the lack of URN support in, e.g., web browsers, the URNs are
   usually expressed as URLs when embedded in documents.  The Finnish
   URN registry is located at <>, and URNs are therefore
   expressed in the form<URN>.  For example, the URI
   <> identifies Sami Nurmi's
   doctoral dissertation "Aspects of Inflationary Models at Low Energy

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   Any national URN registry can resolve URN:ISBNs with foreign
   registration group element values if a) there is a URN:ISBN
   resolution service for that country, b) the national resolution
   service is aware of the existence of the foreign service and how to
   find it, and c) the two resolution services can communicate with one
   another.  The PERSID project (<>) developed
   such an infrastructure for the URN:NBN namespace.

   Alternatively, instead of linking the national resolvers together, it
   is also possible to build international resolvers that copy
   resolution data from several national services, or to create a way
   station which will enable the resolvers to communicate with one
   another.  We can assume that the network of URN:ISBN resolvers will
   grow, and at the same time the set of services they support will also
   grow and become more diverse.  Such development might make these
   union resolvers and way stations more important.

   If a registration group element does not identify a single country
   but a language area, there are at least two means for locating the
   correct national bibliography.  First, it is possible to define a
   cascade of URN registries -- for instance, the German, Austrian, and
   Swiss national registries, in this order --, which collectively is
   aware of resolution services such as national bibliographies for
   ISBN-13s starting with "978-3".  If the German registry is not able
   to find an authoritative resolution service, the request could be
   passed on to the Austrian one, and if there are still no hits,
   finally to the Swiss service.

   Second, the registrant element ranges assigned to the publishers in
   Germany, Austria, and Switzerland by the respective ISBN Agencies
   could be defined directly into the national registries.  This method
   would be more efficient than cascading, since the correct resolution
   service would be known immediately.  The choice between these two and
   possible other options should be made when the establishment of the
   European network of URN registries reaches this level of maturity.

   In some exceptional cases -- notably in the US and in the 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
   registration group element "3".  This is technically appropriate when
   the headquarters or one of the offices of the publisher is located in

   Information about such a book may not always be available in the
   German national bibliography, but via the Library of Congress
   systems.  Unfortunately, the German/Austrian/Swiss URN registries

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   that should in this case be contacted may not be aware of the
   appropriate resolution service.

   However, the problem posed by the international publishers may 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 registration group element "3" should be resolvable via 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.

   A large union catalogue, such as WorldCat maintained by OCLC
   [OCLC-WC] can be used to complement the resolution services provided
   in the national level, or as the default service, if no national
   services exist or are known to the registry from which the query

   Due to the semantic structure of ISBN-13, the registrant element can
   be used as a "hint".  Technically, it is possible to establish a
   number of URN resolution services maintained by different kinds of
   organizations.  For instance, "978-951-0" is the unique ISBN
   registrant element of the largest publisher in Finland, Sanoma-WSOY.
   Resolution requests for ISBNs starting with "978-951-0" can be passed
   to and dealt with the publisher's server, if and when it is made URN-
   aware.  In such a case, resolving the same URN in multiple locations
   MAY provide different services; the national bibliography might be
   able to provide bibliographic information only, while the publisher
   can provide the book itself, on its own terms.  Users can expect
   Resolution services to co-exist and complement one another.  The same
   ISBN can be resolved both as URN and as a Digital Object Identifier
   (DOI) [DOIHOME].  URN-based services hosted by, e.g., a national
   library, might provide only bibliographic metadata, whereas a service
   based on the DOI system provided by the publisher may supply the
   book, parts of the book or various other services.

   Persistence is one of the key features for any persistent identifier
   system.  There are three inter-related aspects of persistence that
   need to be discussed: persistence of the resource itself, persistence
   of the identifier, and persistence of the URN-based resolvers.

   ISBNs are assigned to manifestations (physical embodiments) of books.
   Thus each digital version of a book (PDF, XML and so on) MUST receive
   its own ISBN.  This quarantees that if URI fragment is added to the
   NSS, it remains functional as long as the digital manifestation is

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   Printed books and library catalogues are persistent, so even after
   500 years, a URN:ISBN identifying a printed book can resolve to a
   bibliographic description of the book, which usually tells where the
   book can be found in, e.g., libraries' collections.

   With digital books things get more complicated.  According to ISO
   2108, each product form must have a separate ISBN.  Since digital
   manifestations are not long-lived, future users who try to find and
   old version of an electronic book, are not likely to find that
   version.  Instead there will be several modernized versions of the
   resource, produced via migration.  There might also be a printed book
   with similar intellectual content.  These manifestations of a book
   SHOULD be interlinked (using, for instance, the work level metadata
   record with URN:ISBN links to all manifestations) so as to make a
   user aware of the existence of alternative sources.  Such
   interlinking enables the users to retrieve manifestations which match
   their interests best.  Different users are likely to have different
   preferences.  While some users prefer a modern manifestation which no
   longer has the authentic look and feel, there are users who want the
   "first edition" even if it requires digital archaeology for access.

   Persistence of URN:ISBN resolvers themselves is mainly an
   organizational issue, related to the persistence of organizations
   maintaining them.  URN:ISBN resolution services are currently
   supplied by several national libraries to enable access to their
   legal deposit collections.  These URN:ISBN resolution services are
   likely to be relatively persistent.

4.4.  Additional Considerations

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

   o  Product form and the means of delivery are irrelevant to the
      decision whether a product needs an ISBN or not.  If the content
      meets the requirements of the standard, it gets an ISBN, no matter
      what the file format or the delivery system.

   o  Each product form (manifestation) 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
         versions of digital books.

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      *  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 clear, their interpretation may vary.  As
   already RFC 2288 [RFC2288] pointed 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.

   Since ISBN assignment is a manual process mistakes do happen.  For
   instance, ISBNs are occasionally re-used for another book or another
   manifestation of the same book.  Such human errors are relatively
   rare and do not threaten or undermine the value of the ISBN system as
   a whole.  They are not a serious risk to the URN resolution service
   based on ISBNs.

   Libraries routinely correct ISBN mistakes.  Their catalogs provide
   cross references ("incorrect ISBN -> correct ISBN").  This MUST be
   taken into account in the URN resolution process.  Further details on
   the process of assigning ISBNs can be found in Section 5 (Namespace
   registration) below.

5.  URN Namespace Registration and Use

   The formal URN Namespace Identifier Registration for the pre-2005
   version of the International Standard Book Number (ISBN) was done in
   RFC 3187 [RFC3187].

   The new ISBN standard does not require a new namespace, but the
   registration is renewed here.  The registrant organization has moved
   from Staatsbibliothek zu Berlin - Preussischer Kulturbesitz to The
   International ISBN Agency, London, U.K. Moreover, the description of
   the NSS and resolution details have been amended.

5.1.  URN Namespace ID Registration for the International Standard Book
      Number (ISBN)

   This registration describes how International Standard Book Numbers
   (ISBN) can be supported within the URN framework.

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   [ RFC Editor: please replace "XXXX" in all instances of "RFC XXXX"
   below by the RFC number assigned to this document. ]

   Namespace ID:  ISBN

      This Namespace ID has already been assigned to the International
      Standard Book Number in January 2001 when the namespace was
      initially registered.

   Kind of named resources:

      Manifestations of monographic publications.

   Registration Information:

      Version: 2
      Date: 2012-10-19

   Declared registrant of the namespace:

      Registering Organization: The International ISBN Agency

      Designated Contact Person:
      Name: Ms. Stella Griffiths
      Affiliation: Executive Director, The International ISBN Agency
      Postal: EDItEUR, 39-41 North Road, London, N7 9DP, U.K.
      Web URL: <>

   Declaration of syntactic structure of NSS part:

      The namspace-specific string of 'ISBN' URNs is either an ISBN-13
      (see Section 4.1.2 of RFC XXXX) or an ISBN-10 (see Section 4.1.1
      of RFC XXXX); the former is preferred.

      Example 1: URN:ISBN:978-0-395-36341-6
      Example 2: URN:ISBN:951-0-18435-7
      Example 3: URN:ISBN:951-20-6541-X
      Example 4: URN:ISBN:951206541X

   Relevant ancillary documentation:

      The ISBN (International Standard Book Number) is a unique machine-
      readable identification number, which marks any edition of a book
      unambiguously.  This number is defined in ISO Standard 2108:2005.
      ISBNs has been in use for more than 30 years and they have
      revolutionised the international book-trade. 170 countries and
      territories are officially ISBN members.

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      The administration of the ISBN system is carried out on three
         International agency,
         Group agencies,

      The International ISBN agency is located in London.  The main
      functions of the Agency are:

      *  To promote, co-ordinate and supervise the world-wide use of the
         ISBN system.

      *  To approve the definition and structure of group agencies.

      *  To allocate group identifiers to group agencies.

      *  To advise on the establishment and functioning of group

      *  To advise group agencies on the allocation of international
         publisher identifiers.

      *  To publish the assigned group numbers and publisher prefixes in
         up-to-date form.

      Detailed information about ISBN usage can be found from the ISBN
      Users' Manual [ISBN_UM].  A shorter introduction to ISBN usage can
      be found from the ISBN FAQ web pages [ISBN_FAQs], which also
      include guidelines for the assignment of ISBNs to e-books.

   Conformance with URN Syntax:

      Legal ISBN characters are 0-9 and hyphen for ISBN-13 and 0-9,
      hyphen, and X for ISBN-10.  No percent-encoding is needed.  Hyphen
      carries no semantic content and MAY be dropped from the NSS.

   Rules for Lexical Equivalence of NSS part:

      ISBN numbers are usually printed with the letters 'ISBN' and a
      single blank preceding the ISBN proper (for instance: ISBN 951-
      746-795-8).  The data preceding the ISBN MUST NOT be included in
      the NSS.  No percent-encoding is needed.

      Prior to comparing the NSS of two ISBN-based URNs for equivalence,
      all hyphens, if present, MUST be removed and letter 'X'
      capitalized.  Prior to comparing a URN based on ISBN-10 with a URN
      based on ISBN-13, the ISBN-10 MUST be converted to the ISBN-13
      form.  This step is necessary since it is not possible to know if

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      the ISBN-10s have been converted to the new form; libraries SHOULD
      keep the old ISBN since it is the one printed in books published
      prior to 2007, while publishers MAY convert the old identifiers
      originally assigned in ISBN-10 form and use the equivalent ISBN-
      13s in unchanged reprints of the books, which according to the
      ISBN assignment rules should not receive a new ISBN.

      Note that the prefix "URN:ISBN:" is case-insensitive; generic URI
      parsing and comparison software frequently uses lower case as the
      canonical (normalized) form.

      Note that URI fragment and/or query, if present, are not part of
      the NSS and MUST be removed before the lexical equivalence is
      determined.  Thus urn:isbn:978-951-1-25645-8,
      urn:isbn:978-951-1-25645-8?s=U2C and
      urn:isbn:978-951-1-25645-8#chapter2 are lexically equivalent,
      although the URN resolvers will treat them in a different manner.

      The URNs are equivalent if the normalized forms compare equal.

   Usage of query instructions:

      URN:ISBN resolvers MAY support several global services.  Some of
      them have been specified in RFC 2483; some remain unspecified.
      Examples of existing relevant services are URI to URL or URLs, URI
      to URN or URNs, URI to resource or resources, and URI to URC or
      URCs.  The component directive is relevant especially to the URI
      to URC service, where it can be used to, e.g., indicate the
      preferred metadata format or the completeness of the metadata
      record or the metadata content requested such as table of
      contents.  A URN resolver maintained by a national library may
      consult for instance the national bibliography, digital asset
      management systems and digital preservation systems to supply
      these services.

      Examples of services which may be specified and implemented in the
      future: request the oldest and most original manifestation of the
      resource; request the latest version of the resource and request
      metadata related to the work.

   Usage of fragment part:

      If URI-to-resource service is used and the media type supports the
      use of URI fragment parts, the users can ustilize that to indicate
      locations within the identified resources since ISBNs are assigned
      to one and one only manifestation of a resource.

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      The URN:ISBN Namespace does not impose any restrictions of its own
      on the fragment identifiers allowed, beyond what the respective
      media type admits.

   Identifier uniqueness considerations:

      ISBN is a unique identifier.  An ISBN, once it has been assigned,
      MUST NOT be re-used for another book or another product form
      (manifestation) of the same book.

      URN:ISBNs inherit the uniqueness properties from ISBNs.  Please
      note that the same ISBN can be used in another persistent
      identifier system, such as DOI or Handle.  The resulting
      persistent identifier is likely to provide different resolution
      services than URN:ISBN.

      If there are multiple manifestations of a single literary work
      such as a novel, each one MUST receive a different ISBN.  ISTC
      (International Standard Text Code, ISO 21047-2009) enables
      identification of textual works.  See
      <> for more information.  Annex
      E of the ISTC standard describes the relations between ISTC and
      publication identifiers such as ISBN.

   Identifier persistence considerations:

      ISBN is a persistent identifier.  Once a book has received an
      ISBN, it MUST NOT get a new ISBN.

      URN:ISBNs inherit the persistence properties from ISBNs.

      Since ISBNs are attached to manifestations, a URI fragment, if
      attached to the URN:ISBN, is as persistent as the ISBN itself.
      Support for URI query is likely to be less persistent, since it is
      dependent on applications supporting the functionality requested.

   Process of identifier assignment:

      Assignment of ISBNs is controlled, and URN:ISBNs inherit this
      property.  There are three levels of control: the international
      agency, group agencies that typically operate in the national
      level, and finally each publisher is responsible of using the ISBN
      system correctly.  Small publishers may demand ISBN numbers one at
      a time by contacting the ISBN group agency.  Large publishers
      receive ISBN blocks from which they allocate ISBNs to the books
      according to the ISBN assignment rules.

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   Process for identifier resolution:

      See Section 4.3 of RFC XXXX.

   Validation mechanism:

      The check digit helps to assure the correctness of an ISBN number
      assigned for a book when it has been entered or processed.
      Applications processing bibliographic data such as integrated
      library systems MAY check the correctness of both ISBN-10 and
      ISBN-13 (and make conversions between the two).  If the number is
      wrong due to, e.g., a typing error made by a publisher, a correct
      ISBN SHOULD be assigned afterwards.  Although the book will only
      contain the wrong number, national bibliography and system used by
      the book trade often will contain both the wrong and new, correct
      ISBN number.


      ISBN is a global identifier system used for identification of
      monographic publications.  It is very widely used and supported by
      the publishing industry.

6.  Security Considerations

   This document proposes means of encoding ISBNs within the URN
   framework.  An ISBN-based URN resolution service is depicted here
   both for ISBN-10 and ISBN-13, but 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 rights associated with objects
   identified by the ISBNs are also beyond the scope of this document,
   as are questions about rights to the databases that might be used to
   construct resolvers.

   Beyond the generic security considerations laid out in the underlying
   documents listed in the Normative References (Section 9.1), no
   specific security threats have been identified for ISBN-based URNs.

7.  IANA Considerations

   IANA is asked to update the existing registration of the Formal URN
   Namespace 'ISBN' using the template given above in Section 5.1, which
   follows the outline specified in RFC 3406bis

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8.  Acknowledgements

   This draft version is the outcome of work started in 2008 and brought
   to the IETF in 2010 to launch a much larger effort to revise the
   basic URN RFCs.  The aim in the IETF is to bring these RFCs in
   alignment with the current URI Standard (STD 63, RFC 3986), ABNF, and
   IANA guidelines.  The participants of project PERSID
   (<>) contributed significantly to the standards

   Leslie Daigle has provided valuable guidance in the initial draft
   stage of this memo.

   Stella Griffiths has advised and guided the development of this
   document, has verified the technical content from the director's view
   of the International ISBN Agency, and provided valuable comments.

   Larry Masinter, Subramanian Moonesamy, Julian Reschke, and other
   participants of the URNbis working group have provided review
   comments and text suggestions that have improved this document.

9.  References

9.1.  Normative References

              Hoenes, A., "Uniform Resource Name (URN) Syntax",
              draft-ietf-urnbis-rfc2141bis-urn-03 (work in progress),
              October 2012.

              Hoenes, A., "Defining Uniform Resource Name (URN)
              Namespaces", draft-ietf-urnbis-rfc3406bis-urn-ns-reg-03
              (work in progress), October 2012.

   [ISO1]     ISO, "Information and documentation - The International
              Standard Book Number (ISBN)", ISO 2108-1992, 1992.

   [ISO2]     ISO, "Information and documentation - The International
              Standard Book Number (ISBN)", ISO 2108-2005, 2005.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, January 2005.

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9.2.  Informative References

   [DOIHOME]  International DOI Foundation, "The Digital Object
              Identifier System", <>.

              IANA, "URI Schemes Registry",

              IANA, "URN Namespace Registry",

   [ISBNORG]  International ISBN Agency, "",

              International ISBN Agency, "ISBN Prefix Ranges",

              International ISBN Agency, "ISBN Prefix Ranges",

   [ISBN_UM]  International ISBN Agency, "ISBN Users' Manual",

   [OCLC-WC]  OCLC WorldCat, " The World's Largest Library
              Catalog", <>.

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, May 1997.

   [RFC2288]  Lynch, C., Preston, C., and R. Jr, "Using Existing
              Bibliographic Identifiers as Uniform Resource Names",
              RFC 2288, February 1998.

   [RFC2611]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "URN Namespace Definition Mechanisms", BCP 33, RFC 2611,
              June 1999.

   [RFC3044]  Rozenfeld, S., "Using The ISSN (International Serial
              Standard Number) as URN (Uniform Resource Names) within an
              ISSN-URN Namespace", RFC 3044, January 2001.

   [RFC3187]  Hakala, J. and H. Walravens, "Using International Standard
              Book Numbers as Uniform Resource Names", RFC 3187,
              October 2001.

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   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", BCP 66, RFC 3406, October 2002.

Appendix A.  Draft Change Log

   [[ RFC-Editor: Whole section to be deleted before RFC publication. ]]

A.1.  draft-hakala-rfc3187bis-isbn-urn-00 to draft-ietf-urnbis-*-00

   - formal updates for a WG draft;
   - RFC 2288 now obsoleted and made Historic;
   - added references to rfc2141bis and rfc3406bis;
   - Sect.3 reorganized and amended: Namespace/Community Considerations;
   - registration template adapted to rfc3406bis [-00];
   - numerous editorial fixes and improvements.

A.2.  draft-ietf-urnbis-rfc3187bis-isbn-urn-00 to -01

   - discussion on persistence altered, based on list discussion;
   - changes and amendments to discussion of URN resolution services;
   - discussion of fragment part usage added;
   - broken link to ISBN manual fixed based on feedback from [ISBNORG];
   - various editorial fixes and enhancements.

A.3.  draft-ietf-urnbis-rfc3187bis-isbn-urn-01 to -02

   - addressed review comments by LM and SM;
   - cleanup of requirements language, but
   - kept RFC 2119 terms where non-canonical/non-intuitive behavior of
   resolver systems is specified;
   - URLs for ISBN user manual (new public version) etc. updated;
   - numerous editorial updates, fixes, and enhancements.

A.4.  draft-ietf-urnbis-rfc3187bis-isbn-urn-02 to -03

   - use of URI fragment is now allowed since they are not part of the
   - namespace registration template updated to conform with the -03
   version of the rfc3406bis draft
   - a few editorial updates, fixes, and enhancements.

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Authors' Addresses

   Maarit Huttunen
   The National Library of Finland
   P.O. Box 26
   Helsinki, Helsinki University  FIN-00014


   Juha Hakala
   The National Library of Finland
   P.O. Box 15
   Helsinki, Helsinki University  FIN-00014


   Alfred Hoenes (editor)
   Gerlinger Str. 12
   Ditzingen  D-71254


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