Node-red-contrib-opcua, "event Node", what to fill in the field "root node"?

Hello,
I would like to read out all my alarm events from my OPC-UA server (Siemens, Sinumerik controller).
With the "client" node from "Node-red-contrib-opcua" I can get a connection with the server.
In front of that node I placed the "event node" but there is nothing coming out.
In the event node you have to fill in the field "root node" but I don't know what to fill in there.
In an example it says: i=2253
Where can I find what to fill in here?

I did get the alarm events out of the server in UA-expert, see last picture

image

Thank you in advance,

Kind regards,

Frits

pls, refer to this post, m also trying the same things. able to collect alarm and events in UA expert, got stuck in node-red.