Ummm, If the 3/1's are IJS (Intermediate Jump Shifts) showing invitational values and 6+ cards, wouldn't 1♠-1N;2♥-3m show an invitational hand and =5= cards? Say something like x.xxx.KQxxx.AQxxx ? 2N could then show invitational hands that were less shapely, say something like xx.Kxx.Kxx.Axxxx or Ax.Ax.Kxxx.xxxxx Playing this style, your only options with a minimum responding hand after 1♠-1N;2♥-?? would be to pass or take a preference to 2♠ Since the Forcing or Semi forcing 1N response has the known problem of hiding Responder's shape on many occasions, IMHO the style I'm suggesting is better.