Record file

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 files and plugin files. Record files can be viewed using the GECK or Creation Kit, or with third-party tools like xEdit.

Master file
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.

Plugin file
A plugin file, 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.

Load order
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.

Record
Records are the individual structures of information that make up record files.

Record signature
Each record has a record signature that denotes its type. Some common record signatures are shown below:

Fallout 4

 * Fallout4.esm (base game)
 * DLCRobot.esm (Automatron)
 * DLCworkshop01.esm (Wasteland Workshop)
 * DLCCoast.esm (Far Harbor)
 * DLCworkshop02.esm (Contraptions Workshop)
 * DLCworkshop03.esm (Vault-Tec Workshop)
 * DLCNukaWorld.esm (Nuka-World)