Field books (primary source documents that are created during field research and that are of big importance for natural history) are unique because they come in a variety of formats and material types. The recent D-Lib Magazine features an article by Sonoe Nakasone and Carolyn Sheffield, “Descriptive metadata for field books: methods and practices of the Field Book Project”. In an earlier post I talked about the project, but this article now goes into more detail regarding the descriptive metadata used for the Field Book Registry. It was decided that these items are going to be described both on the collection and the item level. Metadata schemas from the museum, archives and library communities were chosen for this task: Natural Collections Description (NCD) is used for collection level records and Metadata Object Description Schema (MODS) for item level records, with Encoded Archival Context (EAC) being used for authority records of collectors, organization and expeditions. These schemas are combined into one database, the Field Book Registry. Explicit connections are established between collection, item and authority records via IDs, and controlled vocabularies like the Thesaurus of Geographic Names (TGN) or LCSH enrich the records. The articles closes with screenshots of the cataloging interface and with mentioning some challenges and future developments.