<div class='sourceset sourceset-common'>Common</div>

```kotlin
public object TransitionKey :
        NavMetadataKey<AnimatedContentTransitionScope<Scene<*>>.() -> ContentTransform>
```

The key for `NavEntry.metadata` or [Scene.metadata](/jetpack-compose/androidx.navigation3/navigation3-ui/interfaces/Scene) to notify the [NavDisplay](/jetpack-compose/androidx.navigation3/navigation3-ui/objects/NavDisplay) of how the
content should be animated when adding to the backstack.

**IMPORTANT** [NavDisplay](/jetpack-compose/androidx.navigation3/navigation3-ui/objects/NavDisplay) only looks at the [Scene.metadata](/jetpack-compose/androidx.navigation3/navigation3-ui/interfaces/Scene) to determine the final
[ContentTransform](/jetpack-compose/androidx.compose.animation/animation/classes/ContentTransform). It is the responsibility of the [Scene.metadata](/jetpack-compose/androidx.navigation3/navigation3-ui/interfaces/Scene) to decide which
[ContentTransform](/jetpack-compose/androidx.compose.animation/animation/classes/ContentTransform) to return, whether that be from the `NavEntry.metadata` or something
custom.

**HOW TO USE** Within the `metadata` DSL, invoke `MetadataScope.put` and pass [TransitionKey](/jetpack-compose/androidx.navigation3/navigation3-ui/objects/NavDisplay.TransitionKey)
as the key. The `value: AnimatedContentTransitionScope<Scene<*>>.() -> ContentTransform?`
should be the [ContentTransform](/jetpack-compose/androidx.compose.animation/animation/classes/ContentTransform) to be used when adding to the backstack.