From Halopedia, the Halo wiki
Universe and lore
It is made up of several levels, each easily accessible to the next through the use of ramps and gravity lifts. One section of the map, the third level which is separated by a shield that players can go through, but projectiles can not, is also exposed to the vacuum of space, in which sound effects are somewhat muffled,. In this area, gravity decreases, allowing players to jump further than in lower tiers.
The following are locations on the map that are so named on the player's heads-up display during gameplay:
During production it was called Aftship, a reference to Midship which also took place on a Covenant ship.
The map now looks darker and more detailed than it did in its first appearance in Carnàge Carnivàle.