# OpcClient.IsSubtypeOf Method

> Reference: Determines whether the type identified by subtypeId derives from the type specified by typeId.

<dl class="api-definition">
<dt>Type</dt>
<dd><a href="./">OpcClient</a></dd>
<dt>Namespace</dt>
<dd><a href="../namespaces/opc.uafx.client">Opc.UaFx.Client</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">OpcClient Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

<span class="api-meta">since v2.19</span>

Determines whether the type identified by `subtypeId` derives from the type specified by `typeId`.

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

```csharp
public bool IsSubtypeOf(OpcNodeId subtypeId, OpcNodeId typeId)
```

</div>

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

```vbnet
Public Function IsSubtypeOf(
    subtypeId As OpcNodeId,
    typeId As OpcNodeId) As Boolean
```

</div>

**Parameters**

| Name | Type | Description |
|---|---|---|
| `subtypeId` | [OpcNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodeid/) | The [OpcNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodeid/) of the type to compare with the type identified by `typeId`. |
| `typeId` | [OpcNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodeid/) | The [OpcNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodeid/) of the type to compare with the subtype identified by `subtypeId`. |

**Returns**

[Boolean](https://learn.microsoft.com/dotnet/api/system.boolean)

The value true if the type identified by the `subtypeId` derives from the type identified by `typeId`; otherwise the value false. This method also returns false if `typeId` and `subtypeId` refer to the same type.

**Exceptions**

| Exception | Condition |
|---|---|
| [ArgumentNullException](https://learn.microsoft.com/dotnet/api/system.argumentnullexception) | The `subtypeId` or `typeId` is a null reference (Nothing in Visual Basic). |
| [LicenseException](https://learn.microsoft.com/dotnet/api/system.componentmodel.licenseexception) | The license is expired. |
| [ObjectDisposedException](https://learn.microsoft.com/dotnet/api/system.objectdisposedexception) | The object has been disposed of. |
| [OpcException](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcexception/) | The service execution failed upon different circumstances; for more details see exception details. |