This appendix provides a complete reference of BL4’s file structure, asset organization, and content layout.
Overview
| Engine |
Unreal Engine 5.5 |
| Asset Format |
IoStore (.utoc/.ucas) with Zen packages |
| Total Assets |
~119,299 files in pak archives |
| Extracted to Manifest |
81,097 assets |
| Internal Codename |
Oak2 |
| Max Players |
4 |
File Locations
Steam (Linux)
~/.steam/steam/steamapps/common/Borderlands 4/OakGame/Content/Paks/
Steam (Windows)
C:\Program Files (x86)\Steam\steamapps\common\Borderlands 4\OakGame\Content\Paks\
Pak Chunk Contents
| pakchunk0-Windows_0_P |
Core game assets, weapons, gear |
| pakchunk2-Windows_0_P |
Audio (Wwise .bnk) |
| pakchunk3-Windows_0_P |
Localized audio |
| pakchunk10-Windows_0_P |
Large assets |
Top-Level Content Structure
OakGame/Content/
├── AI/ # Enemy AI, NPCs, bosses
├── Atlases/ # Texture atlases
├── Cinematics/ # Cutscene assets
├── Common/ # Shared materials/resources
├── Dialog/ # Dialogue assets
├── Editor/ # Editor-only assets
├── Fonts/ # Font assets
├── GameData/ # Core game configuration
├── Gear/ # All equipment
├── GeometryCollections/ # Physics destruction meshes
├── Gore/ # Gore effects
├── Grapple/ # Grappling hook system
├── InteractiveObjects/ # World interactables
├── LevelArt/ # Level-specific art
├── LevelLighting/ # Lighting setups
├── Maps/ # Game maps/levels
├── Missions/ # Mission data
├── Pickups/ # Item pickup visuals
├── PlayerCharacters/ # Vault Hunters
├── UI/ # UI assets
├── uiresources/ # UI resource files
├── WeatherOcclusionBakedData/
└── World/ # World building assets
Player Characters (Vault Hunters)
PlayerCharacters/
├── Customizations/ # Player cosmetics
├── DarkSiren/ # Character: Dark Siren
├── ExoSoldier/ # Character: Exo Soldier
├── Gravitar/ # Character: Gravitar
├── Paladin/ # Character: Paladin
├── _Shared/ # Shared character resources
└── Temporary/ # Development/testing
Gear System
Equipment Types
Gear/
├── ArmorShard/ # Armor shard items
├── Enhancements/ # Enhancement items
├── Firmware/ # Firmware upgrades
├── Gadgets/ # Deployable gadgets
│ ├── HeavyWeapons/ # Heavy weapon gadgets
│ ├── Terminals/ # Terminal gadgets
│ └── Turrets/ # Turret gadgets
├── GrenadeGadgets/ # Grenades
│ ├── Manufacturer/
│ │ └── VLA/ # Vladof grenades
│ └── _Shared/
├── RepairKits/ # Repair kit items
├── ShieldBooster/ # Shield boosters
├── shields/ # Shields
│ ├── BalanceData/
│ ├── Manufacturer/
│ │ └── VLA/ # Vladof shields
│ └── _Shared/
├── Vehicles/ # Vehicle equipment
│ └── HoverDrives/ # Hover drive upgrades
├── Weapons/ # Guns
└── _Shared/ # Shared gear resources
├── BalanceData/
│ ├── Anoints/ # Anointment system
│ ├── Economy/ # Currency/cost data
│ └── Rarity/ # Rarity definitions
Weapon System
Gear/Weapons/
├── _Manufacturer/ # Manufacturer-specific data
│ ├── BOR/ # Borg
│ ├── JAK/ # Jakobs
│ └── TED/ # Tediore
├── Pistols/ # Pistol weapons
├── Shotguns/ # Shotgun weapons
├── SMG/ # SMG weapons
├── Sniper/ # Sniper weapons
└── _Shared/
└── BalanceData/
├── BarrelData/ # Barrel parts
├── _BaseWeaponData/ # Base weapon stats
├── BorgChargeData/ # Borg charge mechanics
├── COV/ # COV overheat/repair
├── Elemental/ # Elemental damage types
├── MagazineData/ # Magazine parts
├── Order/ # Order faction weapons
├── Rarity/ # Weapon rarity modifiers
├── ScopeData/ # Scope parts
├── TED/ # Tediore-specific data
├── UnderbarrelData/ # Underbarrel attachments
├── UniqueData/ # Legendary/unique data
└── WeaponStats/ # Base stat definitions
GameData System
GameData/
├── Activities/ # Activity/event system
├── Animation/ # Animation configs
├── Audio/ # Audio settings
├── Balance/ # Game balance tables
│ └── Structs/
│ ├── Struct_ChallengeReward_ECHOTokens
│ └── Struct_BossReplay_Costs
├── Cinematics/ # Cinematic triggers
├── Damage/ # Damage system
│ └── StatusEffects/ # Status effect definitions
├── DataTables/ # Generic data tables
│ └── Structs/
│ ├── Struct_FloatColumn
│ └── Struct_BaseDamage
├── Discovery/ # Discovery/exploration system
├── Globals/ # Global game settings
├── Impacts/ # Impact effects
├── Input/ # Input bindings
├── Loot/ # Loot system
│ ├── Balance/
│ │ └── DataTables/
│ │ ├── Struct_EnemyDrops
│ │ └── Struct_DedicatedDropProbability
│ └── LootSchedule/
├── Lootables/ # Lootable containers
├── Map/ # Map data
├── Missions/ # Mission definitions
├── StatusEffects/ # Status effect data
├── WaypointPath/ # Navigation paths
└── WorldPainter/ # World generation
AI System
AI/
├── ArmyBandit/ # Bandit enemy faction
├── ArmyOrder/ # Order enemy faction
├── Bosses/ # Boss enemies
│ ├── GrassBoss/
│ ├── Guardian/
│ ├── MountBoss/
│ ├── ShatterBoss/
│ ├── TKBoss/
│ └── _Shared/
├── Creatures/ # Non-humanoid enemies
├── Critters/ # Small creatures
├── NPC/ # Non-enemy NPCs
└── _Shared/ # Shared AI resources
File Naming Conventions
| Struct_* |
Structure definitions |
Struct_EnemyDrops |
| DT_* |
Data Tables |
DT_WeaponStats |
| Body_* |
Body/mesh definitions |
Body_Pistol_01 |
| DST_* |
Destruction definitions |
DST_Barrel |
| M_* |
Materials |
M_Metal_Base |
| MI_* |
Material Instances |
MI_Weapon_Red |
| MF_* |
Material Functions |
MF_Damage_Flash |
| AS_* |
Animation Sequences |
AS_Reload |
| Script_* |
Blueprint scripts |
Script_WeaponFire |
| StatusEffect_* |
Status effects |
StatusEffect_Burn |
Weapon Part Types
From NexusConfigStoreInventory in DefaultGame.ini:
Core Weapon Parts
| body |
Main weapon body |
| body_acc |
Body accessories |
| body_mag |
Body magazine attachment |
| body_ele |
Body elemental |
| body_bolt |
Bolt mechanism |
| barrel |
Weapon barrel |
| barrel_acc |
Barrel accessories |
| barrel_licensed |
Licensed barrel variants |
| magazine |
Magazine |
| magazine_acc |
Magazine accessories |
| magazine_borg |
Borg magazine type |
| magazine_ted_thrown |
Tediore thrown magazine |
Attachment Parts
| scope |
Optical scopes |
| scope_acc |
Scope accessories |
| rail |
Rail attachments |
| bottom |
Bottom attachments |
| grip |
Weapon grip |
| foregrip |
Forward grip |
| underbarrel |
Underbarrel attachment |
| underbarrel_acc |
Underbarrel accessories |
| underbarrel_acc_vis |
Visible underbarrel accessories |
Manufacturer-Specific
| tediore_acc |
Tediore accessories |
| tediore_secondary_acc |
Tediore secondary accessories |
| hyperion_secondary_acc |
Hyperion secondary accessories |
| turret_weapon |
Turret weapon parts |
Element & Augments
| element |
Primary element |
| secondary_ele |
Secondary element |
| secondary_ammo |
Secondary ammo type |
| primary_augment |
Primary augment slot |
| secondary_augment |
Secondary augment slot |
| enemy_augment |
Enemy-dropped augment |
| active_augment |
Active skill augment |
| endgame |
Endgame modifications |
| unique |
Unique/legendary parts |
Grenade Parts
| payload |
Grenade payload |
| payload_augment |
Payload augment |
| stat_augment |
Stat augment |
| curative |
Healing effect |
| augment |
General augment |
| utility_behavior |
Utility behavior |
Class Mod Parts
| class_mod_body |
Class mod body |
| action_skill_mod |
Action skill modifier |
| core_augment |
Core augment |
| core_plus_augment |
Core plus augment |
| passive_points |
Passive skill points |
| special_passive |
Special passive abilities |
| stat_group1/2/3 |
Stat groups |
Other
| firmware |
Firmware upgrades |
| augment_element |
Elemental augments |
| augment_element_resist |
Elemental resistance |
| augment_element_nova |
Nova effect |
| augment_element_splat |
Splat effect |
| augment_element_immunity |
Elemental immunity |
| detail |
Detail parts |
| skin |
Weapon skins |
| vile |
Vile rarity parts |
| pearl_elem |
Pearl elemental |
| pearl_stat |
Pearl stat bonus |
Key DataTables
Weapon Naming
| /Game/Gear/Weapons/_Shared/NamingStrategies/WeaponNamingStruct |
Weapon prefix naming |
| /Game/Gear/Weapons/_Shared/NamingStrategies/DAD_LicensedPart_Table_Struct |
Daedalus licensed parts |
| /Game/Gear/Weapons/_Shared/NamingStrategies/TED_PayloadPrefix_Table_Struct |
Tediore payload prefixes |
Balance Data
| /Game/Gear/Weapons/_Shared/BalanceData/BarrelData/* |
Barrel stat modifiers |
| /Game/Gear/Weapons/_Shared/BalanceData/MagazineData/* |
Magazine stat modifiers |
| /Game/Gear/Weapons/_Shared/BalanceData/Rarity/* |
Rarity tier modifiers |
| /Game/Gear/Weapons/_Shared/BalanceData/Elemental/* |
Elemental damage data |
| /Game/GameData/DataTables/Structs/Struct_BaseDamage |
Class mod stat tables |
Asset Path Mapping
Game paths use /Game/ prefix:
| /Game/Gear/Weapons/… |
OakGame/Content/Gear/Weapons/… |
| /Script/OakGame.ClassName |
Engine script class (not extractable) |
Gear Types Found
| ClassMod |
Character class modifications |
| Enhancement |
Enhancement items |
| Firmware |
Firmware upgrades |
| Gadget |
Deployable gadgets |
| Grenade |
Grenade items |
| RepairKit |
Repair kits |
| Shield |
Shield equipment |
New Systems in BL4
BL4 introduces several systems not present in BL3:
| Repair Kits |
Healing/repair items |
| Enhancements |
Enhancement slot items |
| Firmware |
Firmware upgrade system |
| Gadgets |
Turrets, Terminals, Heavy Weapons |
| Armor Shards |
Armor shard items |
| Shield Boosters |
Shield booster pickups |
| Hover Drives |
Vehicle hover drive upgrades |
| Borg |
New manufacturer with charge mechanics |
| Pearl |
Pearl rarity tier |
| Vile |
Vile rarity tier |
Notes
Structure vs Data: Files named Struct_* are type definitions (schemas), not actual data tables.
IoStore Format: BL4 uses UE5’s IoStore container format with Zen packages.
Missing Data: Per-item balance data is derived from parts at runtime rather than stored in data files.
Compression: BL4 uses Oodle compression for IoStore containers.
Extracted from BL4 game files using retoc and uextract tools.