Goto

goto property of server response is optional.

Goto Step / Sub Flow

Use this response to goto a step or sub flow:

{
    "version": "v1",
    "content": {
        "goto": "SOMETHING"
    }
}

You can goto:

Goto	SOMETHING =	e.g.

Find a sub flow and follow steps 1 and 2 in the following screenshot:

Select a step, click "Copy Ref Url for this step", paste somewhere, then you will see the node_ns of this step: