---
title: overlay
framework: diskimagekit
role: symbol
role_heading: Type Property
path: diskimagekit/diskimage/layertype-swift.struct/overlay
---

# overlay

An overlay layer that inherits its size from the layer beneath it.

## Declaration

```swift
static let overlay: DiskImage.LayerType
```

## Discussion

Discussion Overlay layers store all the changed blocks from the layers beneath it in the stack. This variant inherits the size from the layer beneath it. To create overlay layers with a specific block count, use overlay(blockCount:) instead.