A Batch FX pipeline always terminates with a BFX Output node. This node is created automatically when you enter Batch FX from the timeline, and can't be deleted.
You can generate both RGB and alpha results from a BFX Output node to the timeline.
Since an effect you create in Batch FX is a setup applied directly to one or more timeline segments, you can choose to render your BFX directly in Batch FX, or wait until you return to the timeline.
Naming Output Nodes
To help you organize outputs, you can automatically name an Output node with the name of any output socket in the process
tree. With the Output node selected in the schematic, press N and click a node output—the name of the Output node is updated. If you want to change the Output node name, or if you change
the name of the original output socket, simple redo the naming process.
Outputting an Alpha to the Timeline
You can output alpha results in addition to the RGB result from a BFX Output node. You connect the RGB result to the front input of the BFX Output node, and the alpha result to the matte input of the BFX Output node (The output node now displays BFXa). Both results are fed directly to the timeline.
An Axis Timeline FX is automatically added on output, provided that the Add Axis On Matte Output button in the Batch FX section of the Preferences menu is enabled (this is the default).