It was the writing by Ian Bent and William Drabkin of the General Preface to the English translation of Der Tonwille (New York: Oxford University Press, 2004–2005), entailing as it did examining much of Schenker's correspondence with Universal Edition and the attorneys involved in the potential court proceeding between the two contending parties, that gave the initial impetus to what is now Schenker Documents Online.

Phase 1 : Schenker Correspondence Project : 2003–2007

An independent web-based project entitled The Schenker Correspondence Project, the purpose of which was to publish all Schenker's correspondence in a scholarly, digital edition, was launched in 2003. This was co-ordinated from the UK by Professors Ian Bent and William Drabkin, the editing done by a small international team of scholars, the data held on the servers of Columbia University in the City of New York using the webblog software package MovableType, with a linked website on the server of the University of Cambridge Faculty of Music, for both of which invaluable technical support was provided by those institutions. The first document went up on the site on June 12, 2004.

2003–2007 marked phase 1 of the project, and served as a pilot for an eventually larger, more comprehensive undertaking; it was almost entirely unfunded. The years 1900–1912 formed the primary focus of Schenker's correspondence for phase 1, emphasis being placed on Schenker's two principal publishers, Universal Edition and J. G. Cotta—although correspondence from later years (Angi Elias, August Halm, Maximilian Harden, Oswald Jonas, Felix-Eberhard von Cube, Viktor Zuckerkandl, and others) was also published. Some 500 items of correspondence were posted to the web during this phase.

Phase 2 : Schenker Documents Online : 2007–2010

So important did Schenker's diaries prove to be in corroborating his correspondence that for phase 2, spanning 2007–2010, the scope of the project was expanded to include both Schenker's diaries and his lessonbooks, with the aim of providing the end-user with fluid movement among the three categories of documents. In 2007, the project was retitled Schenker Documents Online (SDO). Funding was obtained from the Leverhulme Trust in the UK for three years specifically to design and deliver a new web environment using XML encoding and following TEI guidelines: the design work was carried out at the Centre for Computing in the Humanities at King's College London, on whose servers the project would in future be maintained. For phase 2, the focus shifted to the eight-year period 1918–25, one which saw the emergence of Urlinie and Ursatz and the beginnings of layered voice-leading analysis, and in which the outcome of World War I and ensuing economic stringency had a major impact on Schenker's thinking. Correspondence with Universal Edition again occupied a central place, along with other correspondence streams (Guido Adler, Wilhelm Furtwängler, Anthony van Hoboken, the Gesellschaft der Musikfreunde, Felix Salzer, Moriz Violin, Hans Weisse, and others).

For phase 2, Schenker Documents Online entered into collaboration with a team of scholars working at the Universität für Musik und Darstellende Kunst in Vienna, who transcribed and translated Schenker's diaries for 1918–25 in extenso, delivering XML-encoded files for publication on SDO. This work was funded for three years by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung (FWF). Funds were provided by other British trusts for the supply of document scans and for other purposes. The new web environment was released in its first version in September 2009.

Phase 3 : SDO : 2011–2014

Phase 3, running throughout 2011–2014, focussed primarily on the period October 1925 to September 1930, the period in which Schenker arrived at the final formulation of his theory, and resumed work on Der freie Satz. Emphasis was placed on Schenker's correspondence with the third of his three main publishing houses, Drei Masken Verlag of Munich, with the engravers Waldheim-Eberle of Vienna, and with those involved in their publication of Das Meisterwerk in der Musik (Otto Erich Deutsch, Alfred Einstein, and others) as well as that with Universal Edition, the content of which interlocks with that of DMV; and also on the diaries for 1925‒30 and the lessonbooks for the seasons 1925/26 to 1929/30. This phase was funded by a large grant from the Arts & Humanities Research Council of Great Britain. During this phase, some transfer of correspondence from the Columbia site was carried out, and some editing of new material outside the 1925‒30 framework (e.g. Walter Dahms, Viktor Hammer).

For phase 3, Schenker Documents Online was based at the Department of Music of the University of Southampton in collaboration with the Department of Digital Humanities of University of London King's College. The Principal Investigator was William Drabkin, Co-Investigators were Paul Spence and Andrea Reiter, with post-doctorate fellows Marko Deisinger and David Bretherton and PhD candidates Kirstie Hewlett and Georg Burgstaller. As part of the AHRC project plan, SDO published Heinrich Schenker: Selected Correspondence, edited by Ian Bent, David Bretherton and William Drabkin and published by The Boydell Press of Woodbridge, Suffolk. This 568-page volume presents some 450 letters in English translation, organized into six sections devoted to aspects of his professional life, with extensive introductory materials and supporting commentary.

In March 2013 the members of the phase 3 project team presented papers at a special Schenker Documents panel at the Fifth International Schenker Symposium, hosted by the Mannes College; these will be published in the journal Music Analysis, Vol. 34, No. 2 (July 2015).

Phase 4 : 2014‒2017

Phase 4 now comprises three main initiatives. First, the team of scholars in Vienna which completed the transcribing and translating of Schenker's diaries 1918‒30 during phases 2 and 3 is currently extending that series to Schenker's death in January 1935, and will then embark on the middle-period diaries 1912‒17. The team's work, headed by Martin Eybl, is funded as in phase 2 by the FWF. Transcription is by Marko Deisinger, translation by William Drabkin (with annotations by both), editorial work by Kirstie Hewlett, and XML encoding by Iby Jolande-Varga.

Second, the correspondence (some 750 items) encoded during phase 1 and the early part of phase 2 in MovableType on the Columbia University website (which is still publicly accessible) is now being systematically transferred to, and XML encoded on, the main site. The most voluminous collections are those with Universal Edition, Josef Weinberger, and J.G. Cotta, encompassing 1901 to 1912, but important collections also exist with numerous private persons, for example Felix-Eberhard von Cube, Wilhelm Furtwängler, August Halm, Oswald Jonas, and Julius Röntgen (those with Anthony van Hoboken and Felix Salzer having been transferred during phase 3). Once made public on the main site, these will be "unpublished" from the old site, with links to the new.

Third it is hoped to make progress with publishing Schenker's lessonbooks and notes, already edited by Robert Kosovsky, on the site. These entail not only translation but also exceptionally heavy editing and encoding work, which is why progress has been so slow hitherto. In addition, there is a large number of profiles awaiting encoding and publication. These second and third initiatives are being carried out without funding. At the same time, the completion of correspondences already underway, and the publishing of new correspondences continues.

Policy Matters

Without exception, from the beginning to the present day, all transcribing, translating, and interpreting of documents contributed to SDO by scholars in the USA, UK, and Europe, has been done entirely out of the goodwill of those scholars, without payment of any sort. (For further details, see "Contributing Scholars.")

A vital part of the work of SDO from the outset has been the obtaining of permission from the holders of intellectual copyright to publish documents to the web. To date, there have been no refusals, and no limitations have been placed on SDO by the descendants and representatives of the authors of these materials, who have shown only cooperation and generosity to the project. (For further details, see "Clearances.")