# OpcCertificateValidationRules Enum

<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 validation rules which can be additionally applied to the default validation rules of a certificate validation.

## Syntax

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

```csharp
public enum OpcCertificateValidationRules
```

</div>

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

```vbnet
<Flags>
Public Enum OpcCertificateValidationRules
```

</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) → **OpcCertificateValidationRules**

## Fields

| Name | Value | Description |
|---|---|---|
| <a id="default"></a>`Default` | `0` | Only system defined (= default) validation rules are used to validate a certificate. |
| <a id="disablebackwardscompatiblevalidation"></a>`DisableBackwardsCompatibleValidation`<span class="api-meta">since v2.54</span> | `2` | A certificate is validated against the latest recommended validation rules without considering backwards compatible validation behaviour. |
| <a id="rejectsha1signed"></a>`RejectSHA1Signed` | `1` | A certificate which has been signed using SHA1 is to be rejected. |

## Applies to

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