CDM is the Common (Meta-)Data Model of the resources published by the Publications Office of the European Union
It is an ontology based on the FRBR model, described by using RDF(S)/OWL technologies, able to represent the relationships between the resource types managed by the Publications Office and their views according to the FRBR model in terms of Work, Expression, Manifestation and Item.
In CDM all types of documents created/issued by the European institutions, the activities (mainly legislation) by which the documents are created and the relations between the objects are described formally.
The documentation for the CDM version currently active in the Common Repository (Cellar) can be obtained by dereferencing the ontology URI http://publications.europa.eu/ontology/cdm