Folder node can be placed in parallel with MainProgram.
Is there any purpose for this?
It seems to do nothing. In the script file generated when saving the program there is no sign of nodes inserted in those folders. Maybe it is only a place to keep unused nodes, instead of commenting them.
I have used it before when writing long programs, to store sections of code that I will need to paste into various places as im programming
It provides a clean way to label chunks of code (like cases which can’t be renamed), and the best way to copy and paste complete sections of code