6.—(1) The adjudicator may require the attendance of any person (including a party to the proceedings) as a witness, at a time and place specified by him, at the hearing of an appeal and require him to answer any questions or produce any document in his custody or control which relate to any matter in the proceedings.
(2) Where the adjudicator makes a requirement under paragraph (1) he shall make reference to the fact that, under section 73(14) of the Act, any person who without reasonable excuse fails to comply with this requirement shall be liable on summary conviction to a fine, and he shall state the amount of the maximum fine current at that time.
(3) A person in respect of whom a requirement has been made under paragraph (1) may apply to the adjudicator to vary or set aside that requirement.
(4) A person shall not be bound to comply with the requirement under paragraph (1) unless he has been given at least 7 days' notice of the hearing or, if less than 7 days, he has informed the adjudicator that he accepts such notice as he has been given.
(5) A person other than an appellant shall not be bound to comply with the requirement under paragraph (1) unless the necessary expenses of his attendance are paid or tendered to him.
(6) No person shall be required to give any evidence or produce any document under paragraph (1) which he could not be required to give or produce in proceedings before a court.