# IExtensionListDef Interface

Namespace: [Qlik.Engine](https://help.qlik.com/en-US/sense-developer/November2025/Subsystems/NetSDKAPIref/Content/Qlik.Engine.htm)  
Assembly: Qlik.Engine.dll

Obsolete, use qrs API's to fetch extensions.

## Syntax

```
[ValueClass]
public interface IExtensionListDef : IAbstractStructure
```