Core Rules stores all of its campaign information in a set of .dat data files. This section describes, at a glance, what data lives in each file — not the byte-level format, but the kind of information you will find there. For a live field-by-field view of any record, use the RecordViewer diagnostic tool.

Base files vs. user files. Every data type has a base file (in the Database\ folder — the stock content that ships with the product, treated as read-only) and usually a user file (in UserDbas\, the same name with a U appended, e.g. Monster.dat → MonsterU.dat, holding what a DM adds or customizes). When the database loads, the two are merged into a single in-memory table — user records add to, or override by name, the base records — and saving only ever writes the user file. Where a file exists as base-only or user-only, its page notes it.

Character data. Characters are stored separately, in a Chars\ folder: an index.chr roster (one lightweight entry per character — name, file, race, party, PC/NPC flag) plus a per-character .dat file holding each full record, loaded on demand.

The data files (the linked entries are documented now; the rest are being added):

File	Contains
Allowed	Which classes each race may take (user file only)
Attack	Monster attack-form definitions
Character	Player & NPC characters (roster + per-character files)
Class	Character classes
Convert	Old-to-new name conversion table (base file only)
Encount	Pre-built encounters
EncPlat	Encounter templates (encounter generators)
EncTab	2–20 random-encounter frequency tables (user file only)
Monster	The bestiary — individual monsters
MonType	Monster type / category definitions
Parts	General equipment & rules data — 19 categories
Psionic	Psionic powers
Race	Character races
Spells	Wizard & priest spells
Traps	Trap definitions
TreaBun	Treasure bundles
Treasure	Random treasure tables