Production of additional evidence permitted to ensure fair hearing when the tribunal requires documents, witnesses, or affidavits. Parties are ordinarily barred from producing additional evidence before the Appellate Tribunal, but the Tribunal may, for reasons recorded, allow documents, witness examination, or affidavits where necessary to enable it to pass orders or where a party lacked sufficient opportunity; such evidence may be taken before the Tribunal or an authority directed by it, which must comply and transmit records, and the Tribunal may suo motu call for documents or summon witnesses to meet the ends of justice.