What is the standard of review in the context of standard review on mixed fact and law?

At para. 36, Wittmann J.A. continued stating: The standard of review on a pure question of law is correctness; the standard on a question of mixed fact and law, where the issue is the application of a legal standard to a set of facts, is subject to a standard of palpable and overriding error, unless it is clear that the trial judge made some extricable error in principle with respect to the characterization of the standard or its application, in which case the error may amount to an error of law, subject to the standard of correctness: Housen v. Nikolaisen, paras. 26-36.