Nomisma.org is a collaborative effort to provide stable digital representations of numismatic concepts and entities, for example the generic idea of a coin hoard or an actual hoard as documented in the print publication An Inventory of Greek Coin Hoards (IGCH). Nomisma.org provides a short, often recognizable, URI for each resource it defines and presents the related information in both human and machine readable form. Creators of digital content can use these stable URIs to build a web of linked knowledge that enables faster acquisition and analysis of well-structured numismatic data.

Example URIs are:

• http://nomisma.org/id/axis
• http://nomisma.org/id/hoard
• http://nomisma.org/id/igch0262 (with links to CNG and preliminary map of findspot and mints)
• http://nomisma.org/id/igch1240 (with links to SNG and map of findspot and mints)
• http://nomisma.org/id/igch2122 (with links to ANS collection)
• http://nomisma.org/id/igch1546 (with links to ANS and Yale collections)
• http://nomisma.org/id/igch2130

See list of all id's assigned to date.

The current data has been contributed by researchers at the American Numismatic Society, British Museum, The University of Paris-Sorbonne Nomisma project, Yale University Art Gallery. Hosting for Nomisma is provided by the The American Numismatic Society. The following organizations have contributed financial support and/or data.

As a test case, Nomisma.org is developing a digital version of IGCH. All 2387 hoards have been assigned stable URIs and the text from the original publication is online. IGCH is a good dataset with which to explore the potential of nomisma.org because its stable entities, hoards as identified by a unique number, are well known within the field of ancient numismatics. http://nomisma.org/id/igch0156 is recognizable and its semantics are clear: a digital representation of the entity commonly abbreviated as IGCH 156. Furthermore, hoards are usefully conceived of as a set of links to other numismatic entities, with the mints of the coins within each hoard and its findspot being of obvious interest. Nomisma.org will define conventions for identifying the numismatic information inherent within hoards and for turning this information into explicit links. Following the digital publication of IGCH, Nomisma.org will integrate data from the ongoing Coin Hoards series, which will result in information for approximately 4500 hoards being available.

Map of the 2nd Century BC hoard http://nomisma.org/id/igch1544:

A KML file is available at http://nomisma.org/nomisma.org.kml

An XML file of all nomisma.org data is available at http://nomisma.org/nomisma.org.xml

Nomisma.org has adopted the principles of the Semantic Web and Linked Data. Its resources are represented using xml, the Extensible Markup Language. In particular, xhtml with embedded rdf will permit the information to be both human readable and automatically processed. As an indication of the latter, the URI http://nomisma.org/id/igch0156, leads to a description of the hoard that contains an embedded reference to the ancient site of Eretria, the mint for some of the coins in this hoard. The URI for Eretria in turn refers to the Pleiades identifier for that city (http://pleiades.stoa.org/places/579925). The goal is to make this link to the external resource recognizable to third-party processors. The project intends to make all its data available in formats that support independent querying and reuse of its resources.

The default xml namespace is 'http://nomisma.org/id/'.

• Sebastian Heath, Institute for the Study of the Ancient World
• Andrew Meadows, American Numismatic Society
• Daniel Pett, British Museum
• David Wigg-Wolf, Roemisch-Germanische Kommission, Frankfurt

Correspondence can be directed to Heath or Meadows.

Nomisma.org also hosts the Numismatic Description Standard.