sumo referee for san'yaku-ranked bouts
A sumo referee rank; these referees officiate matches involving wrestlers of the san'yaku ranks (komusubi, sekiwake, ōzeki, yokozuna).
A san'yaku-kaku referee can officiate bouts involving ōzeki and yokozuna.
三役 refers to the three highest ranks below yokozuna (komusubi, sekiwake, ōzeki); 三役格 is the referee rank that officiates their bouts.
Compound of 三役 (san'yaku, 'the three highest sumo ranks below yokozuna') + 格 (kaku, 'status, rank'). The term refers to a referee rank qualified to officiate matches of san'yaku-ranked wrestlers.