Procedural Compositing with Batch > Batch Overview > About Batch >
Batch Concepts: Group Nodes

A group node is a selection of nodes and clips that are collapsed into one node icon. Each node icon displays the group’s contents, inputs, and outputs. You can create groups for different branches of your process tree and work on each separately. Groups are useful for simplifying cluttered schematics. See Grouping Nodes.

(a) Group node

A group node is also created when appending a Gateway Clip source setup to a Batch schematic using the Append to current Batch button. This allows you to edit the Batch setup that created the Gateway clip just like you would Clip History.