MetadataPrefix

MetadataPrefix is a parameter used in the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH) to identify the metadata format requested when harvesting records. It serves as a concise label for the encoding of the metadata part of a record, allowing a harvester to request records in a particular schema, such as Dublin Core or MARC, rather than only in a repository's internal format.

In OAI-PMH requests of ListIdentifiers, ListRecords, and GetRecord, the request must include metadataPrefix; the repository responds with records encoded in that format, if supported. The set of supported prefixes is published by the repository via ListMetadataFormats. Common examples include oai_dc (Dublin Core), oai_marc (MARC 21 XML), and oai_qdc (qualified Dublin Core).

If the repository does not support the requested prefix, it returns an error such as cannotDisseminateFormat or badArgument. The actual metadata is carried within a metadata element per record and is governed by the associated metadata schema (URL and namespace).

MetadataPrefix is distinct from the underlying data provider's internal representation and is intended to facilitate interoperable harvesting across repositories.