USE OF THE DIGITAL IDENTIFIER IN ACESSING AND CITING ELECTRONIC JOURNALS OF THE AMERICAN CHEMICAL SOCIETY.
Lorrin R. Garson
Publications Division, American Chemical Society

INTRODUCTION:
To unequivocally identify a journal reference source, the minimal set of information required is (a) identification of the journal, (b) volume or year of publication, and (c) beginning page number of the article.  Thus, "J. Amer. Chem. Soc, 1998, 8417" is sufficient for identification purposes.  However, author's names, issue number, ending page and even titles are often included to provide for a more informative citation.   For example: Per E. M. Siegbahn, "Theoretical Study of the Substrate Mechanism of Ribonucleotide Reductase,"  J. Amer. Chem. Soc, 1998, 120, 8417-8429.

In the case of electronic publication, where there is a reasonable one-to-one relationship between print and electronic content, the same method can be used for the purposes of citation.  However, where content is significantly different between the two formats, or a product exists only in electronic format, the traditional method for journal citation breaks down.  For digital information entities, it is suggested the minimum data needed to identify and access are (a) a unique identifier for the digital entity, and (b) the locus of the digital object itself.  Like traditional methods of citation, the minimal set of information can be made more useful by including much of the same metadata.  However, the main functions of a citation, whether to a print or electronic source, are to identify the source and enable the reader to access that source.

THE DIGITAL OBJECT IDENTIFIER:
The Digital Object Identifier (DOI) offers a practical means to identify, cite and retrieve information in electronic form.  This presentation will be focus on the ACS deployment and use of DOI technology for the World Wide Web editions of its journals.

A DOI consists of two components:  a prefix in the form 10.nnnn, which is assigned by the International DOI Foundation, and a suffix which is assigned by a publisher and has a unique value associated with a specific digital object.   For example, the DOI associated with the above paper by Siegbahn is: 10.1021/ja9736065.  10.1021 is the DOI prefix assigned to the Publications Division of the American Chemical Society and ja9736065 is the manuscript number assigned to this specific manuscript.  Like most publishers, the ACS has been using a well-developed scheme for assigning manuscript numbers for many years.  These numbers, which are unique for each manuscript, are assigned when manuscripts are received for consideration of publication.  Manuscripts numbers are associated with each manuscript through the peer review process, production, and now into electronic formats as well as print.  It is the publisher's responsibility to register DOIs and concomitant URL and to keep URLs current.  The ACS registers DOIs daily.   Information about the DOI and the International DOI Foundation can be found at http://www.doi.org/.

A 'VIRTUAL OBJECT':
There has been considerable discussion in the information community as to what is the most appropriate digital object to refer to in a journal article.  Should this object be the HTML representation of the article? The PDF format?   Should journal articles contain multiple digital objects?  For example should each of the following journal components be a separate digital object: abstract, introduction section, experimental section, an NMR spectrum, a melting point, etc.?   We have taken the approach to associate a journal article with a single digital object that is format independent.  This object is a 'virtual object' which is algorithmically generated and accessed through a specific URL.  In our implementation, the 'virtual page' is generated by a cgi script that displays bibliographic information about the article (authors, title, full journal citation) and allows subscribers to select the abstract, HTML or PDF formats of the complete article.  Non-subscribers may purchase the article using a credit card from the same 'virtual page'. Such a 'virtual object' can be easily changed as technology advances, new types of information are included in journal articles,  or business conditions change.

Again referring to the paper by Siegbahn, the URL associated with the DOI for that article  is: <http://pubs.acs.org/cgi bin/doilookup '10.1021/ja9736065>http://pubs.acs.org /cgi-bin/doilookup'10.1021/ja9736065.   If a search query using the statement <http://dx.doi.org/10.1021/ja9736065>http://dx.doi.org/10.1021/ja9736065 is passed to a DOI resolver, the resolver will return the URL http://pubs.acs.org/cgi-in/doilookup'10.1021/ja9736065>http://pubs.acs.or g/cgi-bin/doilookup'10.1021/ja9736065 which displays the 'virtual page' just described.   Associated URLs linked on the 'virtual page' are as follows:

ABSTRACT:<http://pubs.acs.org/isubscribe/journals/jacsat/jtext.cgi'jacsat/120/i33/abs /ja9736065.html>http://pubs.acs.org/isubscribe/journals/jacsat/jtext.cgi'ja csat/120/i33/abs/ja9736065.html

HTML file:
<http://pubs.acs.org/isubscribe/journals/jacsat/jtext.cgi'jacsat/120/i33/htm l/ja9736065.html>http://pubs.acs.org/isubscribe/journals/jacsat/jtext.cgi'ja csat/120/i33/html/ja9736065.html

PDF file:
<http://pubs.acs.org/isubscribe/journals/jacsat/120/i33/pdf/ja9736065.pdf>ht tp://pubs.acs.org/isubscribe/journals/jacsat/120/i33/pdf/ja9736065.pdf

And to purchase the article using a credit card: <http://pubs.acs.org:8061/UADB/xppview/isubscribe/journals/jacsat/120/i33/pd f/ja9736065.pdf>http://pubs.acs.org:8061/UADB/xppview/isubscribe/journals/ja csat/120/i33/pdf/ja9736065.pdf

The fundamental assumption in this approach is that the basic information unit in journal publishing is the article, of which there are numerous types: communications, letters, research articles, short articles, review articles, letters-to-the-editor, etc.  We believe this basic unit will continue in the foreseeable future, but the contents of articles are likely to become increasingly diverse with the inclusion of true digital data of various types.

AS SOON AS PUBLISHABLE (ASAP):
Since January 1, 1998, the ACS has been making its journal articles available on the World Wide Web 2-11 weeks prior to these articles being printed in issues.  This program is called ASAP (As Soon As Publishable). Articles are posted on the Web following peer review, technical editing, and all corrections have been made following the receipt of page proofs from authors.  Such articles are available in both HTML and PDF formats and are identical to the corresponding print article except no page numbers are available for ASAP articles.  Such articles can be referred to by their DOI which not only uniquely identifies the article but also offers a facile mechanism to access the article.  We have also suggested to authors that when citing ASAP articles in their manuscripts, they refer to the article as being 'in press' and then modifying such citations at the galley or proof page stage to include the full, traditional citation.