AT: "xx" The operations officer was a Starfleet position within the operations division which was common in the 24th century.
Operations officers are responsible for overseeing internal systems control, communications and sensors, while also coordinating the scheduling of resources, hardware, and system usage for an entire starship, outpost, or space station. Operations officers also manned the ops station, which incorporated older 23rd century bridge positions such as communications and science.
The operations position was manned by a member of the command staff of a starship, regardless of seniority. On the starship USS Enterprise-D, Chief Operations Officer Lieutenant Commander Data (doubling as Second Officer) was the most senior member of the ship's crew, after the Captain and first officer, but on the starship USS Voyager, Operations Officer Ensign Harry Kim was the most junior bridge officer.
As analytical operations relied upon knowledge of science and engineering disciplines, chief operations officers often performed the additional duties of a science officer, especially when a dedicated science officer was absent, as exemplified by both Data and Harry Kim. (TNG: "Conundrum"; VOY: "Caretaker", etc.)
This designation was also used on one occasion to describe Chief of Operations Miles O'Brien during his assignment aboard Deep Space 9. (DS9: "Facets")
In an alternate timeline, Daniel Byrd was the operations officer on Voyager instead of Harry Kim, who had remained on Earth. (VOY: "Non Sequitur")