Bulkhead Doors

Bulkhead Doors are a special type of door which was introduced alongside sectors and act as passageway to these sectors. Bulkhead doors share the SEC_DOOR_### with normal security doors

Description
Bulkhead doors are found in most expeditions which feature Sectored Difficulty, usually, they will lead to higher difficulties, Extreme and Overload, but occasionally they will lead to the High difficulty areas, so they are required.

They come in two different sizes, large and small. The large door is a cylindrical shape, curved on both sides. When opened, the center will turn and reveal an entrance. The smaller doors are more spherical in shape but have a flat side on both sides of the door, unlike the large doors, the entirety of this door will spin to reveal the entrance. When opening the doors will seemingly unlock by having pins in the rim of the door come out. In the door itself when opened there are rows of lights which light up.

On the side of the door is a screen which both shows what difficulty the door leads to, and is the place where the door must be opened.

Opening
To open a Bulkhead Door you must first find the Bulkhead Door Controller and place a Bulkhead Key into it, there will then be 1, 2 or 3 scans which each lead to a different difficulty, which is shown on the scans themselves with a word and an icon. Upon completing a scan, the corresponding door will unlock, it must then be opened at the door itself.

Opening a Bulkhead Door can cause various alarms or nothing at all. They cannot, however, be a bloody door like other Security Doors.

After opening a Bulkhead Door, a voice line will play from the door saying which difficulty layer it leads to, this line will play for the rest of the level.