Darwin Core Archive
Darwin Core Archive (DwC-A) is the standard for publishing biodiversity data using Darwin Core terms. It is the preferred format for publishing data in OBIS and GBIF. The conceptual data model of the Darwin Core Archive is a “star schema” with a core record, such as an occurrence or an event, as the center of the star. Extension records, radiating out of the star, can optionally be associated with the core, linked by database keys such as an ID colum. This means that there is only one core file and (optionally) linked to multiple extension files. So the entire schema is only two levels deep: a single core with zero, one, or many extensions. Each core-to-extension relationship can be one-to-one, where there is only one extension record for each core record - also called “Simple Darwin Core”, or one-to-many, where for example many environmental or biometric measurements and/or many biological occurrence records, can be associated with a single sampling event. The biodiversity data and metadata are published using GBIF’s Integrated Publishing Toolkit (IPT). The IPT software assists the user in mapping data to valid Darwin Core terms and archiving and compressing the Darwin Core content with: (i) a descriptor file:
meta.xml that maps the core and extensions files to Darwin Core terms, and describes how the core and extensions files are linked, and (ii) the
eml.xml file, which contains the dataset metadata in Ecological Metadata Language (EML) format. For instructions on how to enter the metadata go to EML. Al these components (i.e. core file, extension files, descriptor file and metadata file), compressed together (as a .zip file), comprise the Darwin Core Archive.