DOI Metadata > DOI Data Model > DOI Data Model Policy > Policy on DOI Metadata Declaration

A metadata declaration must be made for every entity identified with a DOI name according to the following principles:

•The declaration must contain a minimum set of mandatory metadata which is defined through the DOI Kernel Schema. This schema is designed to be as limited in scope as possible, and it is applicable to any entity identifiable by the DOI System.

•Additional metadata can be declared. They should be based on an agreed metadata exchange schema if metadata interoperability is required with other Registration Agencies (RA).

•All declared DOI metadata is based on an underlying ontology through the DOI Kernel Schema which specifies all data elements and allowed values.

DOI data model policy places no restrictions on the form and content of input and service metadata declarations of a Registration Agency (RA), except insofar as input metadata must support the minimum requirements implicit in the DOI Kernel. RAs may specify their own metadata schemes and messages, or use any existing schemes in whole or part for their input and service metadata declarations.