Historical data - it means any description done in the past about the past, be it scientific, medical or cultural – is normally unique and cannot be verified, falsified nor completed in an absolute sense.

In history, any conflict resolution of contradictory records is nothing more than yet another opinion.

So, for an ontology capable to collect and relate knowledge from historical data, ontological principles about how we perceive things must related, and epistemological principles about how knowledge can be acquired must both be respected. There can be huge differences in the credibility of propositions.