---
title: Mod dependencies and compatibility
summary: DLC requirements, unique IDs, conflicting patches and verification after a game update.
section: data
kind: guide
status: reference
updated: 2026-10-27
tags: ["X4","modding","compatibility"]
sources: ["https://wiki.egosoft.com/X4%20Foundations%20Wiki/Modding%20Support/Breaking%20Changes/"]
---
## Declare actual requirements


A basic XML mod should not require a library simply because another project uses it. Declare a dependency only when your code or assets need it. The example below requires the Split DLC. When targeting DLC or another extension, also verify its file namespace: the effective path may differ from a base-game path.




```xml
<dependency id="ego_dlc_split" optional="false" />
```

## Multiple mods can change one attribute


Two valid diffs may target the same field. The effective loaded document determines the result. Inspect that document and the real game value. Test a minimal dependency set first, then the intended compatibility set, and record exact mod versions for reproduction.



## Unique identifiers


Use an extension prefix for macros, components, wares, MD scripts and UI events. Text pages can conflict too. Renaming a file does not rename the IDs inside it.



## X4 updates


For the baseline version, read [9.00 migration notes](wiki:x4-version-migration). For multiple supported games, distinguish [exact and cumulative version catalogs](wiki:version-catalogs).



Read Breaking Changes and inspect the actual files in the new build. Internal menu Lua changes may need additional investigation. Repeat a short test for the affected behavior: loading, a property value, UI action or new ship creation. Check save/load separately.