Disclosing the facts or data underlying an expert’s opinion. Unless the court orders

otherwise, an expert may state an opinion—and give the reasons for it—without first testifying to the underlying facts or data. But the expert may be required to disclose those facts or data on cross-examination. [Report 1983; November 9, 2001, effective February 15, 2002; September 28, 2016, effective January 1, 2017]