Section 247(3)(b) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(b)Engine-Room Artificers, Ordance Artificers, Electrical Artificers, Shipwright Artificers and Aircraft Artificers of a particular class shall rank and command over all Engine-Room Artificers, Ordinance Artificers, Electrical Artificers, Shipwright Artificers and Aircraft Artificers of a lower class. Within one of these branches, sailors of the same class shall rank and command according to their seniority in that class.