# CallbackOptions

> Extra properties that can be used in CallbackEventHandler.RegisterCallback.

## Definition

* **Type:** Enum
* **Namespace:** [UnityEngine.UIElements](/engine/6000.7/script-reference/unityengine/uielements.md)
* **Assembly:** UnityEngine.UIElementsModule

```csharp
[Flags]
public enum CallbackOptions
```

## Fields

| Value                                                                                                        | Description                                                                                                                                                                                                 |
| ------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [Default](/engine/6000.7/script-reference/unityengine/uielements/callbackoptions/default.md)                 | No option enabled.                                                                                                                                                                                          |
| [IncludeDisabled](/engine/6000.7/script-reference/unityengine/uielements/callbackoptions/includedisabled.md) | Callback executes on disabled target even if the event has [\_ignoreDisabledElements](/engine/6000.7/script-reference/unityengine/uielements/eventbase/ignoredisabledelements.md).                          |
| [Once](/engine/6000.7/script-reference/unityengine/uielements/callbackoptions/once.md)                       | Callback is unregistered automatically after being successfully executed.                                                                                                                                   |
| [Removable](/engine/6000.7/script-reference/unityengine/uielements/callbackoptions/removable.md)             | Callback can be unregistered with [CallbackEventHandler.UnregisterAllRemovableCallbacks()](/engine/6000.7/script-reference/unityengine/uielements/callbackeventhandler/unregisterallremovablecallbacks.md). |
| [TrickleDown](/engine/6000.7/script-reference/unityengine/uielements/callbackoptions/trickledown.md)         | Callback reacts during the TrickleDown phase. If not set, callback reacts during the BubbleUp phase.                                                                                                        |