# FirstUserIndex

> Index in the global function table of the first user-defined allocator.

## Definition

* **Type:** Field
* **Namespace:** [Unity.Collections](/engine/6000.7/script-reference/unity/collections.md)
* **Assembly:** UnityEngine.ManagedKernelModule

```csharp
public const ushort FirstUserIndex = 64
```

### Remarks

The indexes from 0 up to `FirstUserIndex` are reserved and so should not be used for your own allocators.