Version 3 of the URREF ontology is an ongoing work and its structure has been "frozen" until Fusion 2019. Until then, we will be making modifications only to the properties as a result of the group's discussions. The URREF ontology code for any version can be obtained from our GitHub page at:

https://github.com/paulocosta-gmu/urref/tree/master.

The official distribution of the ontology (i.e. its OWL file) can be accessed via the URL:

http://eturwg.c4i.gmu.edu/files/ontologies/URREF.owl