# IdAttribute

Package: [Microsoft.Orleans.Serialization.Abstractions](/orleans/docs/api/csharp/microsoft.orleans.serialization.abstractions/) 10.0.0

[NuGet package](https://www.nuget.org/packages/Microsoft.Orleans.Serialization.Abstractions) | [Source](https://github.com/dotnet/orleans/blob/e4e752cedecc2976811db49802c7a999b1f1c704/src/Orleans.Serialization.Abstractions/Annotations.cs#L266)

```csharp
public sealed class IdAttribute : Attribute
```

Specifies the unique identity of a member.

## Remarks

Every serializable member in a type which has [GenerateSerializerAttribute](/orleans/docs/api/csharp/microsoft.orleans.serialization.abstractions/orleans.generateserializerattribute/) applied to it must have one [IdAttribute](/orleans/docs/api/csharp/microsoft.orleans.serialization.abstractions/orleans.idattribute/) attribute applied with a unique [IdAttribute](/orleans/docs/api/csharp/microsoft.orleans.serialization.abstractions/orleans.idattribute/) value.

## See also

- `System.Attribute`

## Constructors

- [IdAttribute(uint)](/orleans/docs/api/csharp/microsoft.orleans.serialization.abstractions/orleans.idattribute/constructors/constructor-uint-1a99edb6/)

## Properties

- [Id](/orleans/docs/api/csharp/microsoft.orleans.serialization.abstractions/orleans.idattribute/properties/id-2a34ca46/)