# IReferenceAware interface

Namespace: [Grasshopper2.Doc](https://developer.rhino3d.com/api/gh2/namespace/grasshopper2.doc.md) · Assembly: [Grasshopper2](https://developer.rhino3d.com/api/gh2/assembly/grasshopper2.md)

```cs
public interface IReferenceAware
```

Any [IDocumentObject](https://developer.rhino3d.com/api/gh2/type/grasshopper2.doc.idocumentobject.md) which wishes to be informed when Rhino objects change must implement this interface.

**Derived types:** [IParameter](https://developer.rhino3d.com/api/gh2/type/grasshopper2.parameters.iparameter.md)

## Methods

- [ExpireReferences](https://developer.rhino3d.com/api/gh2/type/grasshopper2.doc.ireferenceaware/expirereferences.md): Expire all references which match a validator method.