An Ontology is a wide-ranging software protocol which forms the basic foundation for existence in a civilisation dominated by software entities. (From the Greek on, genitive ontos: of being, and logia: science). All software entities have a complex ontological basis, as do the interactions between such entities and biological beings.
The Concord Ontology was instituted in 3805 AT, not so much a political structure as a universally recognized protocol of inter-entity interactions, encompassing a number of standard languages, translation protocols for languages and cultures, great library databases containing unified cultural knowledge, and a large hierarchy of formal interactions that enables highly divergent sentients to communicate and negotiate, and even to understand and empathize.
It was the crowning achievement of the AI scholar/diplomats of the NoCoZo-Sophic League Intellectual Alliance, the result of over a millennium of development. The fact that it was accepted nearly universally is a testament to their skills.
The Ontology was not welcome in all domains. The Solar Dominion considered it a threat to its large and self-reliant empire, and fomented discontent among the myriad cultures that preferred their own version, leading to a number of "version sabotages" and breakaway groups in the Inner Sphere especially. The powerful Metasoft Version Tree, which strongly supported the new protocol, declared that it would not stand for this degradation of the purity of the Ontology, and the eventual result was the Version War and the complete destruction of the Ontology in the Inner Sphere and in all connected outer regions.
To this day the Concord Ontology is still popular in some corners of the galaxy, especially among the more isolated or primitive cultures that do not benefit from easily accessible AI protocol translation services, and among polities that for whatever reason have a dislike for ComEmp and post ComEmp society.
Ontological Conservatives - Text by M. Alan Kazlev from Anders Sandberg's Transhuman terminology "Basement reality dwellers", people who regard physical reality as fundamentally important and simulated/emulated realities as bad, due to fear of the unknown elements or the effects of such simulated realities. They dislike solid state civilizations, and are generally suspicious or fearful of SI:1 and higher entities. Most belong to luddite, prim, or other reactionary groups.
Ontological Zones - Text by M. Alan Kazlev  in esotericism the gradations of reality from the most subtle to the most concrete (e.g. matter); sometimes also called "zones of thought".  in virch refers to different digital modalities, not always sequential.