The current version of SCO is based on Seleucid Coins: A Comprehensive Catalogue by Arthur Houghton, Catharine Lorber, and Oliver Hoover, published in two parts in 2002 and 2008 by American Numismatic Society and Classical Numismatic Group, Inc. The first part, by Houghton and Lorber, presented and interpreted all the numismatic material for Seleucus I to Antiochus III known up to 2002. The second part, by Houghton, Lorber, and Hoover, did the same for the Seleucid kings from Seleucus IV to Antiochus XIII. In total, more than 2,491 primary coin types were published in these volumes.
Ultimately, SCO will provide wide access to the coins listed in the print volumes of Seleucid Coins—not only the entries in the main catalogue, but also pieces presented separately in the appendices (e.g., plated issues, non-Seleucid coins bearing Seleucid countermarks, etc.). While the Seleucid coins in the ANS collection (some 5,129 pieces) serve as the core of the searchable catalogue, all types in the original publications will be included in the database, ultimately with links to coins (many of which are unique) in the Bibliothèque nationale de France, the British Museum, the Munzkabinett der Staatliche Museen zu Berlin, and many other public and private collections. When necessary, entries in the catalogue will provide corrections to descriptions and interpretation with explanatory commentary by Oliver Hoover.