The OntoBREP ontology is explained in detail in the following publication:
Alexander Perzylo, Nikhil Somani, Markus Rickert, and Alois Knoll. An ontology for CAD data and geometric constraints as a link between product models and semantic robot task descriptions. In Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Hamburg, Germany, September 2015.