X4: Foundations Modding Reference

A comprehensive reference for developing X4: Foundations mods (extensions). Compiled from Egosoft’s official documentation, game file analysis (v9.00), and community resources.

Sections

Topic	Description
Extension Structure	content.xml manifest, load order, substitution catalogs
Catalog System	.cat/.dat format, naming conventions, override semantics
XML Diff Patching	add/replace/remove operations, XPath, conditional patching
Mission Director	MD scripting: cues, events, actions, variables
AI Scripts	Ship/NPC behavior: orders, interrupts, attention levels
Libraries	Game data XML: wares, jobs, factions, modules
Localization	Translation files, language codes, text references
UI / Lua Scripting	Lua UI modding, Protected UI Mode, kuertee API
Maps, Components, Macros	Index files, macro paths, asset structure
XSD Schemas	Schema hierarchy, extraction, validation
In-Game References	scriptproperties.html, jobeditor, VS Code integration
Build Workflow	Project structure, build commands, installation
Debugging	Debug log, launch parameters, common errors
Common Recipes	Add wares, modify values, MD scripts, NPC jobs, ships
File Types	All file extensions in game archives
Signature Files	RSA signatures, DRM, impact on mods
Common Pitfalls	Top 10 recurring modding mistakes
Quick Reference Links	All official, tool, and community URLs

External resources

Official:

Community:

Example mods:

Genesis Signal – MD game-start event detection
DeadAir Scripts – AI script modifications
kuertee UI Extensions – Lua UI callback system

Table of contents