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# SecTransformMetaAttributeType.required

Indicates whether the attribute value is optional.

```
case required
```

## Discussion

Specifies if an attribute must have a non `NULL` value set or have an incoming connection before the transform starts to execute. This metadata has a default value of <doc://com.apple.documentation/documentation/Swift/true> for the input attribute, but <doc://com.apple.documentation/documentation/Swift/false> for all other attributes.

---

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