'plus' ['n'|'e'|'f'|'p'|'l'|'s'|'b'|'S'|'L'|'sh'|'si']& ->
['a'|'d'|'p'|'q'|'t'|'v'] ->
<set> 'w'|'k'|'r'|'g'|'b'|'y'|'m'|'n'|'t'
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.