# IOpcUnion Interface

<span class="api-meta">since v2.32</span>

<dl class="api-definition">
<dt>Namespace</dt>
<dd><a href="../namespaces/opc.uafx">Opc.UaFx</a></dd>
<dt>Assembly</dt>
<dd>Opc.UaFx.Advanced.dll</dd>
<dt>Package</dt>
<dd>Opc.UaFx.Advanced v2.59.0</dd>
<dt>Members</dt>
<dd><a href="./members">IOpcUnion Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Defines that the implementing data type is to be treat like unions.

## Syntax

<div class="api-signature" data-lang="csharp">

```csharp
public interface IOpcUnion
```

</div>

<div class="api-signature" data-lang="vbnet">

```vbnet
Public Interface IOpcUnion
```

</div>

## Properties

| Name | Description |
|---|---|
| [SwitchValue](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopcunion/members#switchvalue) | Gets or sets the switch value which is evaluated during encoding and decoding of this structure to decide which field is to be decoded or encoded. |

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.32–v2.59 |