You have all nodes here with their explanation so it's not exactly a manual but...
in English...and in French ;)
https://moiscript.weebly.com/biblio-elephant.html

You have Selected Node
https://moiscript.weebly.com/objects.html#bibeselected

and this shows (2 lines bottom) the action on the Select Node on this page : https://moiscript.weebly.com/node.html