Apple Color 1.5 - Manual (Page 288)

The very last node in any node tree must be the Output node. This is the node that sends
the image that’s been processed by the Color FX room back into the Color image
processing pipeline. If there is no Output node, or if the Output node is disconnected,
then the node tree will have no effect on that shot, and its effect will not be rendered by
the Render Queue.
Note: A CFX bar will only appear in the grades track of the Timeline for clips with
connected Output nodes. For more information on correction bars in the Timeline, see
Basic Timeline Elements .
Node Inputs and Outputs Explained
Single input nodes take the image and perform an operation upon it. Single input nodes
can only process one incoming image at a time, so you can only connect a single noodle
to any one input.
Multi-input nodes are designed to combine multiple variations of the image in different
ways, in order to produce a single combined effect. These nodes provide multiple inputs
so that you can connect multiple noodles.
288 Chapter 11 The Color FX Room