# SourceHierarchyChanging

> Raised when the source hierarchy is about to change.

## Definition

* **Type:** Event
* **Namespace:** [Unity.Hierarchy](/engine/6000.6/script-reference/unity/hierarchy.md)
* **Assembly:** UnityEngine.HierarchyModule

```csharp
public event HierarchyView.SourceHierarchyChangingEventHandler SourceHierarchyChanging
```