Glossary

Terms used throughout the docs and the tool.

Creation

A single entry on Bethesda's Creations store — what players loosely call a "mod" when it comes from the official store. May ship one or more plugin files.

Plugin

A single .esm or .esp file inside a creation. One creation may have multiple plugins; they always load together as a group.

ESM / ESP

Bethesda plugin file formats. ESM (Elder Scrolls Master) for master files; ESP (Elder Scrolls Plugin) for regular plugins. The toolkit treats them uniformly.

TES4

The fixed header record at the start of every plugin file. Names the plugin, lists its masters, and carries other metadata. Stands for "The Elder Scrolls 4" — the format predates Starfield.

MAST subrecord

An entry inside the TES4 record naming one master dependency. Each MAST is followed by a DATA subrecord (ignored by the toolkit). The set of MASTs defines which plugins must load before this one.

Master

A plugin file that another plugin depends on. If B lists A as a master, A must load first.

Plugins.txt

The game's load-order file, listing each installed plugin with an enabled flag. The toolkit edits this (and nothing else in the game folder).

ContentCatalog.txt

The game's catalogue of installed creations, with IDs, titles, authors, and file mappings. Read-only from the toolkit's perspective.

LOOT

Load Order Optimisation Tool — the long-standing community sorter for Bethesda games. The toolkit consumes its masterlist (a YAML file) as one of its sorter inputs.

Masterlist

The YAML document maintained by the LOOT team describing plugin groups and load-order rules.

Rule book

A JSON file declaring load-order relationships between creations. Curated rule books ship with the toolkit; user rule books are yours to author. See Rule books.

Tier

A slot in the 11-tier community load-order system, derived from Bethesda Creations categories. See Category tiers.

Sort constraint

A single fact about ordering: load_after, load_before, or tier. Produced by sorters, consumed by the solver.

Sorter

A pipeline stage that reads some source of truth (plugin headers, LOOT, categories, rule books) and emits sort constraints. Each sorter has a priority.

Priority

An integer attached to every constraint, used to resolve conflicts between sorters. Higher wins. See Sorter priority.

Auto-Sort

The pipeline that runs all sorters, merges their constraints, and produces a proposed load order.

Diff dialog

The review UI shown after Auto-Sort completes. Side-by-side current vs proposed, with per-item Apply/Ignore.

Hint dialog

Secondary modal opened from the diff, listing every constraint that touched a given item — winners and losers both.

Snapshot

A saved load-order state. Useful for A/B testing or rollback.

Fast Lanes

Informal name for Bethesda's April 2026 engine update. The Fast Lane Check compares your creations against a snapshot captured just before this update.

Baseline

The bundled snapshot the Fast Lane Check compares against.

Achievement friendly

A flag on each creation indicating whether installing it disables Steam achievements. Reported by the Achievement check.