This issue of D-Lib® Magazine marks the magazine's tenth anniversary. How quickly those years have passed. To celebrate, we have invited articles from ten authors who have been involved in digital library (DL) research from the time when such research began to be recognized as a field in its own right. Four of these ten authors were involved with the launch and funding of D-Lib Magazine as editors (William Arms and Amy Friedlander) or as government program managers (Ronald Larsen, DARPA, and Stephen Griffin, NSF).
The first two articles in this issue this one and the next (by Friedlander) are primarily about D-Lib Magazine itself. This article takes a look at D-Lib's first ten years. In her article, Dr. Friedlander shares her memories as D-Lib's founding editor, including a description of the release of D-Lib's inaugural issue.
The next three articles (by Larsen, Griffin and Mischo) discuss the Digital Libraries Initiative, Phase 1 and Phase 2, as well as other digital library programs and projects. They also outline present challenges and opportunities related to digital library research and development. The last four articles in this issue of D-Lib (by Lynch, Arms, Paepcke, Garcia-Molina, and Wesley, and Weibel) focus on specific areas of digital library research.
D-Lib Magazine goals and accomplishments
From its beginnings in July 1995, the primary goal of D-Lib Magazine has had been to support the digital library community through timely and efficient information exchange. Issues are released monthly, on or near the 15th of the month, except for the July and August issues, which are combined and released in July. D-Lib is made publicly available, free of charge, on the Internet.
To date, 111 issues of the magazine have been produced, in which 548 full-length features (articles, opinions, commentaries, etc.) have appeared. An "In Brief" column was introduced in September 1999, and 538 brief items, as well as numerous excerpts from press releases, have appeared there. The magazine's "Clips and Pointers" column has listed thousands of annotated and hyperlinked current awareness items such as information about new books, reports and proceedings; portals to digital library information; Calls for Participation; and upcoming events, meetings and conferences.
Another feature introduced in 1999 is one that seeks to bring attention to exemplary digital collections, and so far 72 such collections have been featured in D-Lib Magazine. Subject areas covered by the featured collections include science, the arts, the humanities, history, and popular culture, among others. The collections are those of organizations as large and prestigious as the Library of Congress (e.g., American Memory) as well as those of private individuals who have a passionate interest in a specific topic (e.g., Diner City). A complete list of the collections we've featured in D-Lib is at <http://www.dlib.org/title-index.html#F>.
During the planning stage for D-Lib Magazine, it was discussed whether or not digital library articles to be published in D-Lib should be subject to peer review. At the time, a major factor that argued against peer review was the delay that would result before research results could be made available to the DL community. D-Lib's founders opted for quick turnaround from submission to publication over peer review of D-Lib articles. We have revisited that decision periodically over the last ten years, but comments by authors and others have convinced us to keep things the way they are for now. Although not peer reviewed, D-Lib articles have enjoyed a very respectable rate of citation, with an average of 117.6 citations to D-Lib articles per year  (by comparison, a 1998 study by Harter  stated that the median Library and Information Science journal received 54 citations and the median Computer Science journal received 172). Another indicator that authors appreciate the model we use is that 66 percent of the central authors in the field of Digital Libraries have either published in or cited an article from D-Lib Magazine .
Authors of D-Lib articles have also appreciated the magazine's copyright policy under which authors (or in some instances, the authors' organizations) retain copyright to their materials. Authors grant permission to the Corporation for National Research Initiatives (CNRI) to provide access to their materials from our Internet site and the magazine's six mirror sites. Following publication in D-Lib Magazine, many of D-Lib's authors have been asked by and have granted permission to other organizations and publications for their articles to be republished, reprinted, and translated into languages other than English.
At the start of D-lib, most of the articles were solicited. As the reputation of the magazine has grown, the number of unsolicited article proposals, over all, has been increasing at a steady rate, including an increasing number from outside of the US. Thus, even though we accept only a small percentage of unsolicited articles each year, the percentage of unsolicited articles that are disseminated in D-Lib Magazine has grown in comparison to the percentage of articles that we invite.
Experiments that didn't pan out
From October 1995 through January 1999, D-Lib Magazine used the program HyperNews to facilitate reader response to the magazine. For reasons unknown, readers rarely used HyperNews to comment on the magazine's content, and the program was discontinued. We still accept Letters to the Editor, even though the letters received have been few and far between. Anecdotal information from authors indicates that they frequently receive comments directly from readers because we provide authors' email addresses in the article bylines (with the author's permission, of course).
Issues in the first three years of the magazine also included a feature called "The Technology Spotlight," and it was here that new technologies and demonstration projects were showcased. Technology Spotlight also proved not to be as useful as anticipated, and it was discontinued in late 1998.
Some final thoughts
It has been gratifying that DL researchers have asked for and been granted permission to use D-Lib Magazine archives as a testbed for digital library experiments (some of which resulted in D-Lib articles ). Also gratifying is the number of D-Lib article citations over the past 10 years from DL-related conferences and journals (see Table 1 ). As one might expect, the ACM and IEEE conferences on Digital Libraries and the later Joint Conference on Digital Libraries as well as the European Conference on Digital Libraries are listed prominently. However, D-Lib also gets recognition from other related conferences and journals.
D-Lib Magazine owes any success it has achieved to a great many people, as you can see by reading the rather lengthy Acknowledgements section at the end of this article. The magazine's staff is committed to improving the ways in which D-Lib can serve the digital library and the broader information communities, and will continue to add features as time and resources permit.
There would be no magazine without content, and no content without authors who are willing to share the results of their research. A glance at the magazine's author index shows the names of hundreds of authors who have had their work disseminated in D-Lib Magazine over the past ten years.
The magazine would also not have existed without the original sponsorship of DARPA on behalf of the Digital Libraries Initiative (under Grant No. N66001-98-1-8908), and subsequent funding provided by the National Science Foundation (NSF) under Grant No. IIS-0122832 and Grant No. IIS-0243042.
Special thanks are due also to former editors of D-Lib Magazine: Amy Friedlander, William Arms and Peter Hirtle.
Our thanks go to the following people at the Corporation for National Research Initiatives (CNRI): Catherine Rey, the magazine's art director, who has been responsible for the magazine's design and has improved the look of many an image or table submitted by authors; Laurence Lannom, Principal Investigator for the D-Lib project as well as the magazine's technical advisor, who has been unfailingly helpful and tolerant of the Editor's many questions; Robert Kahn, CNRI's CEO, who has provided invaluable support in numerous ways, as has CNRI's counsel, Patrice Lyons.
Thanks, too, to those at the six D-Lib mirror sites who dependably mirror the magazine after each issue is released. Last, but not least, we would like to acknowledge the support of the D-Lib Technical Advisory Board, CNRI colleagues, and others in the community who, when asked, have provided informal technical reviews of articles submitted to D-Lib Magazine.
 Please see Appendix A of this article for details of the approach used to locate citations to D-Lib articles. For this comparison, we computed the average number of citations to D-Lib articles per year. We only considered citations from articles published in 1996-2004 because 1995 and 2005 are not complete publication years for D-Lib Magazine. Considering all sources (ACM GCL, CiteSeer and D-Lib), we found an average of 117.6 citations to D-Lib articles per year. Because we included non-journals, our overall citation numbers are not directly comparable to those reported by Harter . To improve the comparison, we considered only the citations for articles indexed by the ACM Guide to Computing Literature, which focuses on major publishers. Using only articles from the ACM GCL, we found an average of 30.9 citations per year. We note that citations to D-Lib articles from articles in the ACM GCL have grown over time. The average for 2001-2004 is 47.5. While the comparison to the citation medians reported by Harter isn't perfect, it shows that D-Lib has a respectable history of citation.
 See Stephen P. Harter, Scholarly Communication and Electronic Journals: An Impact Study. Journal of the American Society for Information Science, Volume 49, Number 6, pp. 507-516, 1998.
 We were interested in determining what percentage of key individuals within the Digital Libraries community contributed to D-Lib Magazine and/or cited its articles. Recently, Liu et al. conducted a co-authorship analysis using papers from the ACM DL, IEEE DL and later ACM/IEEE JCDL conferences. (See Xiaoming Liu , Johan Bollen, Michael L. Nelson and Herbert Van de Sompel, "All in the Family? A Co-Authorship Analysis of JCDL Conferences (1994-2003)." <http://lib-www.lanl.gov/~xliu/trend.pdf>.) Liu et al. identified a number of central and/or frequently published authors. We took the union of the lists that Liu et al. reported and counted the number of D-Lib articles authored (or co-authored) by these individuals. We also counted the number of D-Lib articles cited at least once by papers on which these individuals were listed as an author. We found that, overall, 66% of these individuals either contributed to D-Lib Magazine or cited at least one article (or both). Thanks to Henry Jerez, CNRI, for pointing out the work of Liu et al. and suggesting the investigation of central authors.
 See, for example, Zhang, Junliang and Javed Mostafa, "Information Retrieval by Semantic Analysis and visualization of the Concept Space of D-Lib® Magazine," D-Lib Magazine, October 2002, <doi:10.1045/october2002-zhang>; and Bollen, Johan, Michael L. Nelson, Giridhar Manepalli, Giridhar Nandigam, and Suchitra Manepalli, "Trend Analysis of the Digital Library Community," D-Lib Magazine, 11(1), January 2005, <doi:10.1045/january2005-bollen>.
 Note that Table 1 reports citations, not articles. For example, if there are 10 citations from a given source those citations could come from 10 papers or from a single paper.
Appendix A - Sources for Citations to D-Lib Magazine Articles
In honor of D-Lib Magazine's 10th anniversary, we conducted a preliminary investigation of the degree to which D-Lib articles have been cited in the Digital Libraries and broader literature.
For this study we drew citation information from three [1A] freely available sources of citation information:
For all three sources, it was necessary to take care in order to attempt to locate all cited articles. D-Lib Magazine uses the Digital Object Identifier (DOI) System [2A] to provide persistent identifiers for its articles. Citations to D-Lib articles used either DOIs or URLs to reference articles. It was necessary to consider both possibilities when searching for citations and to reconcile DOIs and URLs so that all references to each article would be counted correctly. In addition, the ACM Guide to Computing Literature uses Optical Character Recognition (OCR) technology to extract references for their database and CiteSeer uses Autonomous Citation Indexing (ACI) [3A]. Both OCR and ACI are automated and any errors in those processes could have caused us to miss some articles or citations. We searched for combinations of the magazine title and URL and DOI possibilities in an attempt to locate as many articles as possible.
There was some duplication among the three data sources. For example, 35 articles in the Guide to Computing Literature and 8 D-Lib articles are also found in CiteSeer. CiteSeer also contained a number of internal duplicates multiple records for a single article. We performed a manual scan of all citation pairs to remove obvious duplicates. However, some near duplicates may remain, such as technical reports whose titles were changed before publication as a conference paper.
Because we are interested in citations to D-Lib articles over time, for the purposes of this study, we omitted a number of CiteSeer records for which we could not determine the date of publication. To avoid the risk of including duplicates, we also omitted records for which there was scant bibliographic information available (missing or incomplete title or author information). We retained CiteSeer records for technical reports, theses, dissertations, and articles with full title and author information but ambiguous source information if the publication date was available.
[1A] Google Scholar (http://scholar.google.com) is an additional source of freely available information. However, while Google Scholar is a valuable resource for locating technical articles, the truncated bibliographic information provided made this resource poorly suited for our study.
[3A] See Steve Lawrence, C. Lee Giles and Kurt Bollacker, Digital Libraries and Autonomous Citation Indexing, IEEE Computer, Volume 32, Number 6, pp. 67-71, 1999. Available at <http://citeseer.ist.psu.edu/aci-computer/aci-computer99.html>.
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