The Court acts only with respect to the findings and sentence as approved by reviewing authorities, and as affirmed or set aside as incorrect in law by a Court of Criminal Appeals, except insofar as it may take action on a certificate for review or a petition for review of a decision by a Court of Criminal Appeals on appeal by the United States under Article 62, UCMJ,
10 USC §
862 (1983), or to grant extraordinary relief in aid of its jurisdiction, including the exercise of its supervisory powers over the administration of the Uniform Code of Military Justice. The Court may specify or act on any issue concerning a matter of law which materially affects the rights of the parties.