# OpcTypeSystem<T> Class

> Reference: Defines an abstract implementation of the IOpcTypeSystem to define type information used in different scopes of OPC UA.

<span class="api-meta">abstract · since v2.9</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">OpcTypeSystem&lt;T&gt; Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Defines an abstract implementation of the [IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/) to define type information used in different scopes of OPC UA.

## Syntax

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

```csharp
public abstract class OpcTypeSystem<T> where T : class, IOpcType
```

</div>

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

```vbnet
Public MustInherit Class OpcTypeSystem(Of T As {Class, IOpcType})
```

</div>

## Type parameters

| Name | Description |
|---|---|
| `T` |  |

## Inheritance

[Object](https://learn.microsoft.com/dotnet/api/system.object) → **OpcTypeSystem&lt;T&gt;**

## Implements

<ul class="api-implements">
<li><a href="../opc.uafx.iopctypeprovider/">IOpcTypeProvider</a></li>
<li><a href="../opc.uafx.iopctypesystem/">IOpcTypeSystem</a></li>
</ul>

## Derived types

- [OpcDataTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcdatatypesystem/)
- [OpcNodeTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodetypesystem/)

## Constructors

| Name | Description |
|---|---|
| [OpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#opctypesystem)<span class="api-meta">protected · 2 overloads</span> | Initializes a new instance of the OpcTypeSystem&lt;T&gt; class using the `scope` specified without any fallback type system. |

## Properties

| Name | Description |
|---|---|
| [FallbackTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#fallbacktypesystem)<span class="api-meta">virtual</span> | Gets the type system used as the fallback system to query type information which is referenced in the current OpcTypeSystem&lt;T&gt; but is not declared. |
| [IsEmpty](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#isempty)<span class="api-meta">virtual</span> | Gets a value indicating whether the current OpcTypeSystem&lt;T&gt; represents a type system to use if there is no specific type system described. |
| [Scope](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#scope) | Gets the scope of types covered by the current OpcTypeSystem&lt;T&gt;. |

## Methods

| Name | Description |
|---|---|
| [GetType](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#gettype)<span class="api-meta">4 overloads</span> | Retrieves the `T` object which is known under the `name` specified. |
| [GetTypeCore](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#gettypecore)<span class="api-meta">protected · abstract · 4 overloads</span> | Retrieves the `T` object which is known under the `name` specified. |
| [GetTypes](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#gettypes) | Retrieves all `T` objects offered by the OpcTypeSystem&lt;T&gt;. |
| [GetTypesCore](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystem-1/members#gettypescore)<span class="api-meta">protected · abstract</span> | Retrieves all `T` objects offered by the current OpcTypeSystem&lt;T&gt; . |

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.9–v2.59 |