Bunkers

There are two types of Bunkers in RA2/YR:

Battle Bunkers

allow certain InfantryTypes inside for protection and improved firepower,

Tank Bunkers

allow ground-based VehicleTypes to go in for the same.

Battle Bunkers (infantry garrisons) (RA2 & YR)

Buildings that allow infantry to garrison inside need the following tags:

CanBeOccupied=yes
MaxNumberOccupants= ; max number of infantry allowed inside
CanOccupyFire=yes

Infantry that goes inside buildings to garrison them needs these tags:

Occupier=yes
OccupyWeapon=
EliteOccupyWeapon=

(all self-explanatory).

Note: (Elite)OccupyWeapon only exists in YR, in RA2 the weapon used by occupants is set on the structure itself, by setting its Primary. So, all infantry fire the same weapon inside the structure.

Note #2: In YR, all garrisoned units use the [General]OccupyWeaponRange instead of their OccupyWeapon's Range, rendering any sniper garrisons pointless.

Tank Bunkers (vehicle garrisons) (YR)

Buildings that allow tanks to hide inside need these tags:

Bunker=yes
NumberOfDocks=1
NumberImpassableRows=0

The vehicles that are allowed must be:

• Vehicles with Locomotor={4A582741-9839-11d1-B709-00A024DDAFD1} (the ground vehicles one).
  
• Without Bunkerable=no.
  
• Either:
  
  • With a turret.
    
  • With a proper OmniFire=yes weapon.
    
• Drone-free.
  

Tank Bunkers can provide the following improvements to their occupants:

• enhanced weapon Damage (BunkerDamageMultiplier)
• enhanced weapon ROF (BunkerROFMultiplier)
• bonus to weapon Range (BunkerWeaponRangeBonus)

The Tank Bunker usually absorbs the damage instead of the tank within, unless the fired weapon has PenetratesBunker=yes, which is usually the case on aircraft weapons. Also, Tank Bunker protects your vehicles from Terror Drones.

Other notes

It's worth noting that standard YR AI can not effectively use infantry garrisons, due to programmers' laziness. The AI very often uses soldiers to destroy the civilian garrison building instead of garrisonning it. (The YR AI Script Actions include actions especially for Garrisoning buildings and entering tank / battle bunkers.)

Note to mappers: Look at the official Arena (2-4) map. See how close those civilian bunkers are to the player locations? Never do that! The AI will destroy them prior to building it's own base.

Garrisonning a building transfers it's ownership to you, and ungarrisonning it returns the owner to neutral.