This ontology was developed by Holly Zhen, Brian Matthews, Erica Yang at the Science and Technology Facilities Council as part of the PaN data ODI project. More details about the ontology can be found in the PaN data ODI Deliverable 6.4 on "An Evaluation of Metadata Tools and Methods to Assess the Impact and Value of Provenance Management in the PaNData community".
The interesting stuff is in the PanKOS/Version_1.0/ directory. Here you will find the source files in owl, rdf and ttl formats and pdf documentation. Since much of the html in this contains broken links, I created new html rendering. It is in the docs/ directory or online here:
https://ral-facilities.github.io/pankos/
License: CC-BY 4.0