3.—(1) Subject to rule 4, this rule applies in a case where the Board upon receiving the notice of appeal requires further particulars of the grounds on which the appellant intends to rely and of any facts and contentions relevant thereto.
(2) The Board shall within 21 days of receiving the notice of appeal send to the appellant a notice specifying the further particulars required by the Board.
(3) Within 21 days of receiving a notice under paragraph (2), or within such further period as the Board may allow, the appellant shall send to the Board such further particulars.
(4) Subject to the provisions of paragraph (5) the Board shall, within 21 days of receiving such further particulars, send to the Secretary—
(a)the documents specified in rule 2;
(b)a copy of the notice requiring the further particulars; and
(c)such further particulars, and any representations in writing with respect thereto that the Board may think fit.
(5) If such further particulars are not received by the Board in accordance with paragraph (3), the documents mentioned in paragraph (4)(a) and (b) shall be sent by the Board to the Secretary not later than—
(a)the fiftieth day after the receipt of the notice of appeal by the Board; or
(b)if the Board has allowed a further period for the sending of further particulars under paragraph (3), the seventh day after the expiration of that period.