Section 58(2)(b) in M.P. Industrial Disputes Rules, 1957
(b)in the case of workmen, either by the President [or] [Substituted by Notification No. 7014-5052-XVI, dated 5-10-1961.] Secretary of a trade union of workmen, or by five representatives of the workmen duly authorised in this behalf at a meeting of the workmen held for the purpose.