Sector 004 was a region of space. Sector 004/11 included a part of the Romulan Neutral Zone.
In 2364, the Federation starships USS Tranquillity Base, USS Max Plank, and USS Non Sequitur and the starbase Starbase Trailer Twenty-Nine were ordered by Starfleet Command to decrease sensor drone surveillance of this sector. This sector was mentioned in mission orders. (TNG: "Conspiracy", okudagrams)
Sector 004 on a mission order, 2364
Sector 004 on a mission order, 2364
Sector 004 on a mission order, 2364
According to the Star Trek: Star Charts (pg. 19), the Sigma Draconis system was located in this sector, which was also known as the Sigma Draconis sector.