# WorldDefinitionChange

> Event callback for a world definition change event.

## Definition

* **Type:** Event
* **Namespace:** [Unity.U2D.Physics](/engine/6000.6/script-reference/unity/u2d/physics.md)
* **Assembly:** UnityEngine.PhysicsCore2DModule

```csharp
public static event PhysicsEvents.WorldDefinitionChangeEventHandler WorldDefinitionChange
```