Sector Unknown 4 appeared in Operation: I.T. It was one of the locations where operatives were tagging one another. None of the members' codenames were revealed. It's located in Canada. It is possible that the sector's name is Sector CA, since the C is already taken by Sector C. Or instead, the initial of the Canadian province where the sector is located.
Sector unknown 4's operatives are shown to wear things that are associated with Canada. In the two brief showing in operation IT you hear and see two things, one the the Canadain sectors announcing they tagged someone and yelling "EH", and in the next veiwing you see the operatives running to escape broccoli, they are seen wearing Canadian mounted Police uniforms and hockey equipment. This sectors operatives are seen in a several cameos, like in operation TREATY, where a Canadian operative is seen yelling in the conference centre.