What is the test for responding evidence in a medical malpractice case?

What is at issue in the present case is a different form of responsive evidence, recognized in Stainer v. Plaza, supra, as distinct in paragraph 15, where Finch J.A. ( as he then was) noted: The third condition in the order is directed to the third party calling an independent medical examiner "for rebuttal evidence" I understand from counsel that this refers not to rebuttal evidence as generally understood, but to evidence that is purely responsive to medical evidence which the plaintiff has led as part of her case. It would not apply to opinion evidence offered by the third party on subject matters not adduced in the medical evidence adduced by the plaintiff. [underlining added]