# OnSourceChanged

> Only when a change is detected in the source or Binding.MarkDirty() has been called.

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine.UIElements](/engine/6000.3/script-reference/unityengine/uielements.md)
* **Assembly:** UnityEngine.UIElementsModule

```csharp
OnSourceChanged = 1
```