Segmentae Majoris: As part of an effort to improve administration and shipping, the vastness of the Imperium was divided into five major fleet zones the Segmentae Majoris. Originally intended as a solely shipping concern, the Segmentae became separate parts of the Adeptus Terra, each with an Administratum official in charge of affairs within. All shipping within the Imperium is supervised from within one of the Segmentae; merchant vessels and private captains must register their ships and charters with the Master of the Segmentum. Once registered, the vessel and its captain and crew are entered into the records of the Segmentum, as part of the Civilis or Mercantalis Fleets. Segmentum registration is necessary to ply the space lanes safely; unregistered ships are deemed either hostiles or pirates and attacked and destroyed by Imperial warships.
Registration within one Segmentum allows free passage within that Segmentum only; any ship wishing to cross Segmentae borders must register in each Segmentum its Captain intends to travel in, or obtain special permission to move through another Segmentum from its Master.
Each Segmentum has a Segmentum Fortress, and orbital headquarters which doubles as the dwelling for the Segmentum Master and shipyards and barracks for the Segmentum warfleet. The Segmentae are sub-divided into Sectors, the size of which is dependent on local shipping demands and stellar density. An average sector comprises 7 million cubic light years; a 3D cube in space with sides as long as 200 light years.
Sectors further sub-divide into sub-sectors, which usually cover approximately 2 to 8 separate star systems. The size of sub-sectors depends on the effective range of patrol craft stationed in them. Sub-sectors are divisions of inhabited worlds as opposed to the general volumes of space covered by Sectors, which means there can be many systems which are not included within the borders of sub-sectors, and therefore either not patrolled at all or only patrolled by Segmentum Fleets, which reach these areas with much less frequency owing to the sheer size of their responsibilities. These areas, known as inter-sectors, are commonly regarded as wilderness zones, empty space, frontier space and forbidden zones. Inter-sectors are often populated with nebulae, other stellar navigation hazards like black holes and pulsars or neutron stars. They frequently also contain uninhabitable or alien and unexplored worlds.
[table] [tr] [th]Segmentum[/th][th]Zone[/th][th]Fortress[/th] [/tr]
[tr] [td]Segmentum Sola[/td] [td]Central[/td] [td]Mars[/td]
[tr] [td]Segmentum Obscurus[/td] [td]North[/td] [td]Cypra Mundi[/td]
[tr] [td]Segmentum Tempestus[/td] [td]South[/td] [td]Bakka[/td]
[tr] [td]Ultima Segmentum[/td] [td]East[/td] [td]Kar Duniash[/td]
[tr] [td]Segmentum Pacificus[/td] [td]West[/td] [td]Hydraphur[/td]
[/table]
Source: White Dwarf: Issue 139 by various, White Dwarf: Issue 140 by various
Submitter: Simguinus
Hive World Terra