# Unity You can use Unity event nodes to initiate flows in AFX graphs. For more information, see [flows](https://docs.engagevr.io/developer/afx/afx-graphs/flows "mention"). ## Script lifecycle nodes Most of the Unity event nodes that are available relate to stages in Unity's script lifecycle. For more information about the script lifecycle, refer to [Order of execution for event functions](https://docs.unity3d.com/2021.3/Documentation/Manual/ExecutionOrder.html) in the Unity documentation. Nodes that relate to Unity's script lifecycle have a single output port, which initiates a flow when the lifecycle event occurs.

Example node for a stage in the Unity script lifecycle

The following table summarizes the available nodes:

Node	Description
On Enable	Called when the object becomes enabled and active.
Start	Called before the first frame update only if the script instance is enabled.
Fixed Update	Happens at fixed intervals of in-game time rather than per frame.
Update	Called once per frame and is the main function for frame updates.
Late Update	Called once per frame, after `Update` has finished.
On Disable	Called when the object becomes disabled or inactive.

## Timed Update Initiates a flow at defined intervals.

## Inputs

Name	Type	Description
Duration	Float [editable]	The interval, in seconds, between activation of flows.

## Outputs

Name	Type	Description
Exit	Flow	Initiation of a flow.