(1) Subject to the pronswns of sub-rule (2) any notice, summons. process or order issued by the 'controlling authority· may be served either personally or by registered post with acknowledgement due or in any other manner as prescribed under the Code of Civil Procedure 1908 (Act V of 1908).
(2) \Vhere there are numerous persons as par ties to any proceeding before the 'controlling authority· and such persons are members of any trade union or association or are represented by an authorised person, the senice of notice on the Secretary, or where there is no Secretary, on the principal officer of the trade union or associatio'h, or on the authorised person shall be deemed to be sen·ice on such persons.