The OpCit project is developing a reference linking service for Open Archives using the Distributed Link Service and adapting tools for reference linking from PDF documents that were developed in the earlier Open Journal Project ().
Initially the project will hyperlink each of more than 100,000 papers in the Los Alamos physics eprint archive to every other paper in the archive that it cites. The project will extend to link references in papers held in other freely-accessible, distributed archives that conform with the proposal for Open Archives.
Working with the Cornell Digital Library Research Group the project will also investigate the semantics of documents to allow linking, and model interoperability between linking services and other digital library services.
It is hoped that this new way of navigating the scientific journal literature will encourage authors in other fields to create inter-linked online archives like Los Alamos, or Cogprints, across disciplines and around the world. A related project, EPrints, provides free software to enable institutions or special interest groups to build these new online archives.