Internet Info 1997 December/Internet_Info_CD-ROM_Walnut_Creek_December_1997.iso/ietf/urn/urn-archives/urn-ietf.archive.9704/000020_owner-urn-ietf _Wed Apr 16 16:08:09 1997.msg

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Date: Wed, 16 Apr 1997 13:12:08 -0700
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From: Cecilia Preston <[e-mail]>
Subject: [URN] Bibliographic URN's
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At the meeting in Memphis, we decided to put this out to the list again
this time being very carefull that the text be in plain old ASCII.  It
seems what looked just fine to me as I composed the message, didn't
always come out that

way.  Networks....


The file says this is text only.  If anyone has any problems reading
this let me know and we will work something out.


--Cecilia


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Internet Draft                                Clifford Lynch

draft-ietf-urn-biblio-00.txt        University of California

22 March 1997                                Cecilia Preston

Expires in six months                        Preston & Lynch

                                              Ron Daniel Jr.

                              Los Alamos National Laboratory



          Using Existing Bibliographic Identifiers

                             as

                   Uniform Resource Names



Status of this Document


This document is an Internet-Draft.  Internet-Drafts are

working documents of the Internet Engineering Task Force

(IETF), its areas, and its working groups.  Note that other

groups may also distribute working documents as Internet-

Drafts.


Internet-Drafts are draft documents valid for a maximum of

six months and may be updated, replaced or made obsolete by

other documents at any time.  It is inappropriate to use

Internet-Drafts as reference material or to cite them other

than as works in progress.


Distribution of this document is unlimited.  Please send

comments to [e-mail] and [e-mail].


This document does not specify a standard; it is purely

informational.



0. Abstract


A system for Uniform Resource Names (URNs) must be capable

of supporting identifiers from existing widely-used naming

systems.  This document discusses how three major

bibliographic identifiers (the ISBN, ISSN and SICI) can be

supported within the URN framework and the currently

proposed syntax for URNs.




                                                    [Page 1]


INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



1. Introduction


The ongoing work of several IETF working groups, most

recently in the Uniform Resource Names working group, has

culminated the development of a syntax for Uniform Resource

Names (URNs).   The functional requirements and overall

framework for Uniform Resource Names are specified in RFC

1737 [Sollins & Masinter] and the current proposal for the

URN syntax is draft-ietf-urn-syntax-04.txt [Moats].


As part of the validation process for the development of

URNs the IETF working group has agreed that it is important

to demonstrate that the current URN syntax proposal can

accommodate[RD1] existing identifiers from well managed

namespaces.  One such well-established 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.  This Internet draft demonstrates the

feasibility of supporting three representative bibliographic

identifiers within the currently proposed URN framework and

syntax.


Note that this document does not purport to define the

"official" standard way of doing so; it merely demonstrates

feasibility.  It has not been developed in consultation with

the standards bodies and maintenance agencies that oversee

the existing bibliographic identifiers.  Any actual Internet

standard for encoding these bibliographic identifiers as

URNs will need to be developed in consultation with the

responsible standards bodies and maintenance agencies.


In addition, there are several open questions with regard to

the management and registry of Namespace Identifiers (NIDs)

for URNs.  For purposes of illustration, we have used the

three NIDs "ISBN", "ISSN" and "SICI" for the three

corresponding bibliographic identifiers discussed in this

document.  While we believe this to be the most appropriate

choice, it is not the only one.  The NIDs could be based on

the standards body and standard number (e.g. "US-ANSI-NISO-

Z39.56-1997" rather than "SICI").  Alternatively, one could

lump all bibliographic identifiers into a single

"BIBLIOGRAPHIC" name space, and structure the namespace-


                                                   [Page 2]


INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997


specific string to specify which identifier is being used.

We do not believe that these are advantageous approaches,

but must wait for the outcome of namespace management

discussions in the working group.


For the purposes of this document, we have selected three

major bibliographic identifiers (national and international)

to fit within the URN framework.  These are 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].  ISBNs are used to identify monographs

(books).  ISSNs are used to identify serial publications

(journals, newspapers) as a whole.  SICIs augment the ISSN

in order to identify individual issues of serial

publications, or components within those issues (such as an

individual article, or the table of contents of a given

issue).  The ISBN and ISSN are defined in the United States

by standards issued by the National Information Standards

Organization (NISO) and also by parallel international

standards issued under the auspices of 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 does not have a parallel

international standards document at present.


Many other bibliographic identifiers are in common use (for

example, the CODEN, numbers assigned by major bibliographic

utilities such as OCLC and RLG, national library numbers

such as the Library of Congress Control Number) or are under

development.  While we do not discuss them in this document,

many of these will also need to be supported within the URN

framework as it moves to large scale implementation.  The

issues involved in supporting those additional identifiers

are anticipated to be broadly similar to those involved in

supporting ISBNs, ISSNs, and SICIs.



2. Identification vs. Resolution


It is important to distinguish between the resource

identified by a URN and the resources that can reasonably be

provided when attempting to resolve an identifier.  For


                                                    [Page 3]


INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



example, the ISSN 0040-781X identifies the popular

"Time".  All of it, every issue for from the start of

publication to present.  Resolving such an identifier should

not result in the equivalent of hundreds of thousands of

pages of text and photos being dumped to the user's machine.

It is more reasonable for ISSNs to resolve to a navigational

system, such as an HTML-based search form, so the user may

select issues or articles of interest.  ISBNs and SICIs, on

the other hand, do identify finite, manageably-sized

objects, but they may still be large enough that resolution

to a hierarchical system is appropriate.


In addition, the materials identified by an ISSN, ISBN or

SICI may exist only in printed or other physical form, not

electronically.  The best that a resolver may be able to

offer is information about where to get the physical

resource, such as library holdings or a bookstore or

publisher order form.  The URN Framework provides resolution

services that may be used to describe any differences

between the resource identified by a URN and the resource

that would be returned as a result of resolving that URN.



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 [ISO 1]


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,


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INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



* the title identifier,


* and a modulus 11 check digit[RD2], using X in lieu of 10.


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.


3.2 Encoding Considerations


Embedding ISBNs within the URN framework presents no

particular coding problems, since all of the characters that

can appear in an ISBN are valid in the identifier segment of

the URN.  %-encoding 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.


3.3 Additional considerations


The ISBN standard and related community implementation

guidelines define when different versions of a work should

be assigned the same or differing ISBNs.  In actuality,

however, practice varies somewhat depending on publisher as

to whether different ISBNs are assigned for paperbound vs.

hardbound versions of the same work, electronic vs. printed

versions of the same work, or versions of the same work

published for example in the US and in Europe.  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


                                                    [Page 5]


INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



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).



4. International Standard Serials Numbers


4.1 Overview


International Standard Serials Numbers (ISSN) identify a

work that is being published on a continued basis in issues;

they identify the entire (often open-ended, in the case of

an actively published) work.  ISSNs are defined by the

standards ISO 3297:1986 [ISO 2] and ISO/DIS 3297 [ISO 3] and

within the United States by NISO Z39.9-1992 [NISO 1].  The

ISSN International Centre is located in Paris and

coordinates a network of regional centers.  The National

Serials Data Program within the Library of Congress is the

US Center of this network.


ISSNs have the form NNNN-NNNN where N is a digit, the last

digit may be an upper case X as the result of the check

character calculation.  Unlike the ISBN the ISSN components

do not have much structure; blocks of numbers are passed out

to the regional centers and publishers.


4.2 Encoding Considerations


Again, there is no problem representing ISSNs 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.


Example: URN:ISSN:1046-8188


Supplementary comparison rules are also appropriate for the

ISSN namespace.  Just as for ISBNs, hyphens should be

dropped prior to comparison and occurrences of 'x'

normalized to uppercase.



                                                    [Page 6]



INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



4.3 Additional Considerations


The ISSN standard and related community implementation

guidelines specify when new ISSNs should be assigned vs.

continuing to use an existing one.  There are some

publications where practice within the bibliographic

community varies from site to site, such as annuals or

annual conference proceedings.  In some cases these are

treated as serials and ISSNs are used, and in some cases

they are treated as monographs and ISBNs are used.  For

example 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) this is simply the June issue.  On

the other hand you may have acquired this volume as the

conference proceedings (a monograph) and as such would use

the ISBN 0-89791-731-6 to identify the work.  There are also

varying practices within the publishing community as to when

new ISSNs are assigned due to the change in the name of a

periodical (Atlantic becomes Atlantic Monthly); or when a

periodical is published both in printed and electronic

versions (The New York Times).  The use of ISSNs as URNs

will reflect these judgments and practices.



5. Serial Item and Contribution Identifiers


5.1 Overview


The standard for Serial Item and Contribution Identifiers

(SICI) has recently been extensively revised and is defined

by NISO/ANSI Z39.56-1997 [NISO 2].  The maintenance agency

for the SICI code is the UnCover Corporation.


SICI codes can be used to identify an issue of a serial, or

a specific contribution (i.e., an article, or the table of

contents) within an issue of a serial.  SICI codes are not

assigned, they are constructed based on information about

the issue or issue component in question.


The complete syntax for the SICI code will not be discussed

here; see NISO/ANSI Z39.56-1997 for details.  However an

example and brief review of the major components is needed


                                                    [Page 7]


INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



to understand the relationship with the ISSN and how this

identifier differs.  An example of a SICI code is:


0015-6914(19960101)157:1<<62:KTSW>2.0.TX;2-F


The first nine characters are the ISSN identifying the

serial title.  The second component, in parentheses, is the

chronology information giving the date the particular serial

issue was published.  In this example that date was January

1, 1996.  The third component, 157:1, is enumeration

information (volume, number) on the particular issue of the

serial.  These three components comprise the "item segment"

of a SICI code.  By augmenting the ISSN with the chronology

and/or enumeration information, specific issues of the

serial can be identified.  The next segment, <<62:KTSW>,

identifies a particular contribution within the issue.  In

this example we provide the starting page number and a title

code constructed from the initial characters of the title.

Identifiers assigned to a contribution can be used in the

contribution segment if page numbers are inappropriate.  The

rest of the identifier is the control segment, which

includes a check character.  Interested readers are

encouraged to consult the standard for an explanation of the

fields in that segment.


5.2 Encoding Considerations


The character set for SICIs is intended to be email-

transport-transparent, so it does not present major

problems.  However, all printable excluded and reserved

characters from the URN syntax draft are valid in the SICI

character set and must be %-encoded.


Example of a SICI for an issue of a journal


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


For an article contained within that issue


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



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INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997



Special equivalence rules for SICIs are not appropriate for

definition as part of the namespace and incorporation in

areas such as cache management algorithms.  These are best

left to resolver systems which try to determine if two SICIs

refer to the same content.  Consequently, we do not propose

any specific rules for equivalence testing through lexical

manipulation.


5.3 Additional Considerations


Since the serial is identified by an ISSN, some of the

ambiguity currently found in the assignment of ISSNs carries

over into SICI codes.  In cases where an ISSN may refer to a

serial that exists in multiple formats, the SICI contains a

qualifier that specifies the format type (for example,

print, microform, or electronic).  SICI codes may be

constructed from a variety of sources (the actual issue of

the  serial, a citation or a record from an abstracting

service) and, as such are based on the principle of using

all available information, so there may be multiple SICI

codes representing the same article [NISO2, Appenidx D].

For example, one code might be constructed with access to

both chronology and enumeration (that is, date of issue and

volume, issue and page number), another code might be

constructed based only on enumeration information and

without benefit of chronology.  Systems that use SICI codes

employ complex matching algorithms to try to match SICI

codes constructed from incomplete information to SICI codes

constructed with the benefit of all relevant information.


6. Security Considerations


This document proposes means of encoding several existing

bibliographic identifiers within the URN framework.  It does

not discuss resolution; thus questions of secure or

authenticated resolution mechanisms are out of scope.  It

does not address means of validating the integrity or

authenticating the source or provenance of URNs that contain

bibliographic identifiers.  Issues regarding intellectual

property rights associated with objects identified by the

various bibliographic identifiers are also beyond the scope

of this document, as are questions about rights to the

databases that might be used to construct resolvers.


                                                    [Page 9]


INTERNET DRAFT:Bibliographic Identifiers as URNs     3/1997


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] R. Moats, "URN Syntax" draft-ietf-urn-syntax-

       04.text. March 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] K. Sollins and L. Masinter, "Functional

       Requirements for Uniform Resource Names", RFC 1737

       December 1994.


8. Author's Addresses


Clifford Lynch

University of California Office of the President

300 Lakeside Drive, 8th floor

Oakland CA 94612-3550

[e-mail]


Cecilia Preston

Preston & Lynch

PO Box 8310

Emeryville, CA 94662

[e-mail]


Ron Daniel Jr.

Advanced Computing Lab, MS B287

Los Alamos National Laboratory

Los Alamos, NM, 87545

voice: [phone]

fax: [phone]

http://www.acl.lanl.gov/~rdaniel





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