doug, in my experience, ppl lose absurd amounts of time wondering how to find and then align to someone else's ontology rather than just building a solution. you can align to some public standard after the fact very easily.
This also makes downstream consumption easier. no one needs to be concerned about which term comes from which ontology. you standardize on your DIY schema for app dev, and then you align to standards ontologies like d3fend, and use an inference engine to give you the "d3fend" view of your data vs your own native view