A discussion on BBF got me thinking. When the opponents bid and raise spades (1S-P-2S), fourth seat is jammed. A structure to deal with this situation, however, might be worth considering.
1S-P-2S-2NT = both minors, or just diamond (Overcaller will correct 3C to 3D), or just hearts but weak (will correct either minor to 3H)
This part suffers some ambiguity in the 1-2-3 scenario, but that 1-2-3 is often the goal anyway.
1S-P-2S-3C = clubs plus hearts (Michaels style)
1S-P-2S-3D = diamonds plus hearts (Michaels style)
Showing the second suit helps at this level and possibly higher.
1S-P-2S-3H = strong overcall in hearts (like a strong jump overcall)
1S-P-2S-X = takeout OR just clubs
This is really problematic for higher levels, but it at least gets us in there without giving something up but with the gains of the other auctions. Unwinding is simple:
Bid 3D or 3H if you would bid that after a 3C overcall -- if partner has the takeout he is pleased.
Bid 3C if you would bid that after a double -- if partner has just clubs he is pleased.
Bid 2NT (1S-P-2S-X-P-2NT) if you would have preferred a red suit in response to a takeout double. If partner bids 3C, he has "just clubs." If partner bids 3D, this is pass-or-correct.
Any thoughts on this structure? I think I like it, myself.