# OpcAccessLevel Enum

> Reference: Defines the different levels indicating in ways the Value attribute can be accessed (read/write) and if it provides current and/or historic data.

<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>Also in</dt>
<dd>Opc.UaFx.Client</dd>
</dl>

Defines the different levels indicating in ways the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute can be accessed (read/write) and if it provides current and/or historic data.

## Syntax

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

```csharp
public enum OpcAccessLevel
```

</div>

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

```vbnet
<Flags>
Public Enum OpcAccessLevel
```

</div>

## Inheritance

[Object](https://learn.microsoft.com/dotnet/api/system.object) → [ValueType](https://learn.microsoft.com/dotnet/api/system.valuetype) → [Enum](https://learn.microsoft.com/dotnet/api/system.enum) → **OpcAccessLevel**

## Fields

| Name | Value | Description |
|---|---|---|
| <a id="currentread"></a>`CurrentRead` | `1` | The current data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute is readable. |
| <a id="currentreadorwrite"></a>`CurrentReadOrWrite` | `CurrentRead \| CurrentWrite` | The current data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute can be read or written. |
| <a id="currentwrite"></a>`CurrentWrite` | `2` | The current data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute can be written. |
| <a id="historyread"></a>`HistoryRead` | `4` | The [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute provides readable historic data. |
| <a id="historyreadorwrite"></a>`HistoryReadOrWrite` | `HistoryRead \| HistoryWrite` | The historic data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute is readable or can be written. |
| <a id="historywrite"></a>`HistoryWrite` | `8` | The historic data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute can be written. |
| <a id="none"></a>`None` | `0` | The [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute cannot accessed and has no event history. |
| <a id="semanticchange"></a>`SemanticChange` | `16` | Changes of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute generate semantic change events. |
| <a id="statuswrite"></a>`StatusWrite`<span class="api-meta">since v2.8</span> | `32` | The status information associated with the data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute is writable (see [Status](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcvalue/members#status)). |
| <a id="timestampwrite"></a>`TimestampWrite`<span class="api-meta">since v2.8</span> | `64` | The current [SourceTimestamp](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcvalue/members#sourcetimestamp) of the data of the [Value](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcattribute/#value) attribute is writable. |

## Applies to

| Package | Versions |
|---|---|
| Opc.UaFx.Advanced | v2.5–v2.59 |