# OpcModellingRules Class

> Reference: Provides the identifiers of the objects representing the modelling rules of OPC UA and the mapping between them and the members of OpcModellingRule.

<span class="api-meta">static · since v2.27</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">OpcModellingRules Members</a></dd>
<dt>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Provides the identifiers of the objects representing the modelling rules of OPC UA and the mapping between them and the members of [OpcModellingRule](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/).

## Syntax

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

```csharp
public static class OpcModellingRules
```

</div>

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

```vbnet
Public Module OpcModellingRules
```

</div>

## Inheritance

[Object](https://learn.microsoft.com/dotnet/api/system.object) → **OpcModellingRules**

## Fields

| Name | Description |
|---|---|
| [ExposesItsArrayId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#exposesitsarrayid)<span class="api-meta">static</span> | Provides the identifier of the object representing the modelling rule [ExposesItsArray](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/#exposesitsarray). |
| [MandatoryId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#mandatoryid)<span class="api-meta">static</span> | Provides the identifier of the object representing the modelling rule [Mandatory](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/#mandatory). |
| [MandatoryPlaceholderId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#mandatoryplaceholderid)<span class="api-meta">static</span> | Provides the identifier of the object representing the modelling rule [MandatoryPlaceholder](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/#mandatoryplaceholder). |
| [OptionalId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#optionalid)<span class="api-meta">static</span> | Provides the identifier of the object representing the modelling rule [Optional](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/#optional). |
| [OptionalPlaceholderId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#optionalplaceholderid)<span class="api-meta">static</span> | Provides the identifier of the object representing the modelling rule [OptionalPlaceholder](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/#optionalplaceholder). |

## Methods

| Name | Description |
|---|---|
| [GetModellingRule](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#getmodellingrule)<span class="api-meta">static · since v2.50</span> | Retrieves the according [OpcModellingRule](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/) enumeration member for the `nodeId` used by a modelling rule. |
| [GetNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrules/members#getnodeid)<span class="api-meta">static</span> | Retrieves the according [OpcNodeId](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcnodeid/) for the type of rule defined by the [OpcModellingRule](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcmodellingrule/) specified by `rule`. |

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.27–v2.59 |