Portland Common Data Model: Rights Extension 2015-06-03 Ontology for a PCDM extension to add properties for rights overrides. 2015/06/03 rights override Links to a rights statement that overrides the base rights statement attached to a resource. This could be an embargo, temporary license, statutory restriction. rights override expiration Date when a rights override expires. After this date, the base rights rights statement will be in effect. Recommended best practice is to use an encoding scheme, such as the W3CDTF profile of ISO 8601.