13.—(1) A convener or, at the start of a hearing, the Tribunal may, either on the application of a party or on their own initiative, consider and determine any preliminary or incidental issue arising from a reference which must be determined prior to the substantive hearing of the reference, and which cannot be determined by the giving of directions under rule 15.
(2) Before any such issue is determined by a convener or the Tribunal, the convener or the Tribunal may direct that the Secretary gives–
(a)notice to the parties giving them an opportunity to submit representations in writing within a specified period; or
(b)notice requiring the parties to appear before a convener or the Tribunal for a preliminary hearing on that issue.