A record file is a game data file used in the Gamebryo and Creation engines. Record files contain information about in-game items, characters, world spaces, and settings. Game data such as textures, models, sounds, and other assets are found in BSA files rather than record files. Record files come in two forms: master (ESM) files and plugin (ESP) files. Both master and plugin files are found in the Data subfolder of any parent game directory (i.e. where the game's .exe file is found).

Record files can be viewed using the G.E.C.K. or Creation Kit, or with third-party tools like xEdit.[1]

Master fileEdit

A master file, using the .esm file extension, (also called an ESM file, from Elder Scrolls Master) serves as the primary database of game files which plugin files can reference, modify, or add to. They are loaded prior to plugin files.[2]

Plugin fileEdit


Plugin files, using the .esp file extension, (also called an ESP file, from Elder Scrolls Plugin) are largely identical to master files in structure but are loaded after them, and are unable to modify other plugin files.[2] They are intended for use with player mods, as base games and their DLC are both packaged with .esm master files.


The Light Master file, using the .esl file extension is a new optimized file format introduced in the Fallout 4 patch 1.10 update. Using Light Master files will allow more plugins to be loaded than the previously possible due to the 8-bit plugin ID limit of 255. A Light Master does this by using more of the Form ID range for load order, while also sacrificing its maximum capacity for form records. It is primarily used for Creation Club content.

Load orderEdit

Load order determines the order in which mods lay their cards down on the table. Fallout3 goes first, then the next mod in load order, up to the last mod. Whenever two mods conflict, the later loading mod will win.— GECK data files page[2]

The load order of record files determines when changes the files make are applied. Files appearing lower in the load order will overwrite changes made to records by files earlier in the load order.


A Record is any discrete unit of data that gets saved to an .esp file. Base Objects and References are both Records, as are other things such as Game Settings.— Bethesda GECK glossary[3]

Records are the individual structures of information that makeup record files. Each record contains a record header, with information such as a signature, Form ID, Editor ID, data size, flags, and version control information.

Record signatureEdit

The signature within a record's header is what denotes its type. Some common record signatures are shown below:

Signature Record type
ACHR Character reference ID
ACTI Activator
ALCH Consumable item
AMMO Ammunition type
ARMO Armor type
CELL World cell
CONT Container
LSCR Loading screen
MISC Miscellaneous item, weapon/armor modification
NPC_ Non-player character
QUST Quest
RACE Non-player character race
REFR Object reference ID
WEAP Weapon type
WRLD World space

Files present in gamesEdit

Fallout 3Edit

Fallout: New VegasEdit

Fallout 4Edit

Creation ClubEdit

Fallout 76Edit


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