# ResourceAnnotationMutationBehavior

- Kind: `enum`
- Package: [Aspire.Hosting](/reference/api/csharp/aspire.hosting.md)
- Version: `13.4.0`
- Namespace: `Aspire.Hosting.ApplicationModel`
- Target framework: `net8.0`
- Source: [GitHub](https://github.com/microsoft/aspire/blob/a3766e994fd2cba86c8ac60b8a80268cab7e6383/src/Aspire.Hosting/ApplicationModel/ResourceAnnotationMutationBehavior.cs)

Specifies behavior of the `IResourceBuilder`1.WithAnnotation` method when adding an annotation to the [IResource.Annotations](/reference/api/csharp/aspire.hosting/iresource/properties.md#annotations) collection of a resource.

## Definition

```csharp
namespace Aspire.Hosting.ApplicationModel;

public enum ResourceAnnotationMutationBehavior
```

## Enum Members

| Name | Value | Description |
| --- | --- | --- |
| Append | 0 | Append the annotation to the collection. Existing annotations will be kept. |
| Replace | 1 | Replace the existing annotation. The existing annotation will be removed. |