Sector

A sector is a region of space as identified by the United Nations Space Command. Sectors usually contain several star systems, some of which are UNSC colony worlds. Other sectors contain no planets at all.

There appear to be two systems for naming sectors, one for inhabited sectors, one for uninhabited sectors. Inhabited sectors are designated "FLEETCOM Sector X" to denote the division of command the sector's inhabitants fall under. The uninhabited sectors are simply designated "Sector (letter)-(three numbers)'''".

Inhabited Sectors

 * FLEETCOM Sector One
 * FLEETCOM Sector Three

Uninhabited Sectors

 * Sector B-042
 * Sector K-009