18. Service of summons or notice. - Subject to the provisions contained in Rule 20, any notice, summons, process or order issued by a Board, Court, Labour Court, Tribunal or an Arbitrator, empowered to issue such notice, summons, process or order may be served wither personally or by registered post and in the event of refusal by the party concerned to accept the said notice, summons, process or order, the same shall e sent again under certificate of posting. |