When the mental or physical condition or characteristic of a party or of a person in the custody or under the legal control of a party is in controversy, the court may order the party to submit to a mental or physical examination by a suitably licensed or certified examiner or to produce for examination the person in the custody or under the legal control of the party. The order may be entered only on motion for good cause shown and upon notice to the person to be examined and to all parties. It shall specify the time and place, manner, conditions, and scope of the examination and the person or persons by whom it is to be made. The order may regulate the filing and distribution of a report of findings and conclusions and the testimony at trial by the examiner, the payment of expenses, and any other relevant matters.