# overlay

Wafer map: overlay layer (`none` / `defect`).

Canonical: https://chart.syidax.com/docs/options/overlay/

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## Definition

| Item | Value |
| --- | --- |
| JavaScript property | `overlay` |
| HTML attribute | `overlay` |
| Type | `'none' \| 'defect'` |
| Default | `undefined` |
| Allowed values | `none`, `defect` |

undefined means this property was not explicitly set. The effective value may depend on the chart type and other settings.

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## Related documentation

A property with the same name may have different types and defaults across charts. When using a direct tag, follow that chart's documentation below.

- [Shared facade and direct tags](https://chart.syidax.com/docs/concepts.md)
- [sy-wafer-map](https://chart.syidax.com/docs/components/wafer-map.md#property-overlay)