# IOpcTypeSystem Members

> Reference: Provides type information used within a specific scope of OPC UA.

<dl class="api-definition">
<dt>Type</dt>
<dd><a href="./">IOpcTypeSystem</a></dd>
<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>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Inherits members from [IOpcTypeProvider](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypeprovider/members).

## Properties

### FallbackTypeSystem

Gets the type system used as the fallback system to query type information which is referenced in the current [IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/) but is not declared.

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

```csharp
IOpcTypeSystem FallbackTypeSystem { get; }
```

</div>

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

```vbnet
ReadOnly Property FallbackTypeSystem As IOpcTypeSystem
```

</div>

**Property value**

[IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/)

An [IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/) instance used to query type information which is referenced but not declared within the current type system or a null reference (Nothing in Visual Basic) if the current [IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/) is independent from a different type system. Such type systems typically declare types which only reference others declared in the same system as well.

### IsEmpty

Gets a value indicating whether the current [IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/) represents a type system to use if there is no specific type system described.

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

```csharp
bool IsEmpty { get; }
```

</div>

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

```vbnet
ReadOnly Property IsEmpty As Boolean
```

</div>

**Property value**

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

The value true if the type system does not declare a specific type system; otherwise the value false.

### Scope

Gets the scope of types covered by the current [IOpcTypeSystem](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopctypesystem/).

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

```csharp
OpcTypeSystemScopes Scope { get; }
```

</div>

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

```vbnet
ReadOnly Property Scope As OpcTypeSystemScopes
```

</div>

**Property value**

[OpcTypeSystemScopes](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystemscopes/)

One of the members defined by the [OpcTypeSystemScopes](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctypesystemscopes/) enumeration.