Fedora can store metadata in any format, including common formats like XML and JSON. Additionally, Fedora enables RDF properties to be defined for objects it stores or references. This includes all types of metadata, such as technical, rights, provenance, and descriptive. Managing this metadata in Fedora means considering how best to make use of RDF and Linked Data. Some access systems such as Hyrax or Islandora also provide editing and management capabilities for RDF metadata stored as properties in Fedora. See Common metadata design patternsMetadata Design Patterns for examples of ways to take advantage of Fedora's capabilities.
...
It is possible to include and use any ontology that exists, although it is recommended to use ontologies that are shown to be currently active and well-maintained for longevity purposes.
...