The node’s input is used as the output for the first iteration, but subsequent iterations use the output of the previous iteration (that is, the output of the Block End referenced in Block path) to create a feedback loop. This lets you apply the same set of nodes to a piece of geometry over and over.

At each iteration, the output is one “piece” from this node’s input. A piece is defined as all elements where partition attribute such as piece or name has the same value. The piece attribute name is set on the Block End in the Template attribute parameter. If no attribute exists, fetches each point or primitive (according to the Template class on the Block End).

Creates an empty geometry with detail attributes containing information about the current loop. You would use this in a loop created by another Block Begin in “Fetch feedback” or “Fetch piece” mode, and then reference these attributes from inside the loop using the detail function.

See the looping documentation for how to use this.

Copies the input. This is equivalent to just wiring directly past the block begin, but can sometimes result in a more semantically meaningful network.