The first argument determines what operation the action performs and how subsequent arguments are interpreted:

new, [name] | Create a new live script and open a new live script dialog. name is an unique live script name that identifies the window. If not specified, "default" is used"
load, name, [filename] | Replace the script source in the LiveScript window identified by name with the content loaded from a file. If filename is not specified, open a file selector dialog.
save, name, [filename] | Save the script source in the LiveScript window identified by name to a file. If filename is not specified, open a file selector dialog.
run, name | Run the script in the LiveScript window identified by name.
stop, name | Stop the script in the LiveScript window identified by name, if ti is running in persistent mode.
undo, name | Undo the "init changes" of the script in the LiveScript window identified by name. Init changes are those board changes the script has done while running its initialization section. Live script undo is possible only if there was no user edit after the script finished.
rerun, name | Stop, undo and run the script in the LiveScript window identified by name.