# IoIdAttribute class

Namespace: [GrasshopperIO](https://developer.rhino3d.com/api/gh2/namespace/grasshopperio.md) · Assembly: [GrasshopperIO](https://developer.rhino3d.com/api/gh2/assembly/grasshopperio.md)

```cs
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct, AllowMultiple = false)]
public sealed class IoIdAttribute : Attribute
```

An attribute which associates an ID with a serialised object. This is usually required for the deserialisation of derived types, where it isn't clear which exact type is required to parse a specific portion of a file stream.

## Constructors

- [IoIdAttribute](https://developer.rhino3d.com/api/gh2/type/grasshopperio.ioidattribute/ctor.md): Create a new Identifier from a formatted GUID.

## Properties

- [Id](https://developer.rhino3d.com/api/gh2/type/grasshopperio.ioidattribute/id.md): Gets the identifier associated with this attribute.