'plus' ['n'|'e'|'f'|'p'|'l'|'s'|'b'|'S'|'L']&['a'|'d'|'p'|'q'|'v'] -> <set> 'w'|'k'|'r'|'g'|'b'|'y'|'m'|'i'This keyword is used to display the entities of an additional set after a plot command was used (see also minus). Further details are explained in section ``plot''.