(from System "NIGHTMARE" by Buratti & Lanzarotti)
Classic preempts.
Constructive in 1/2 seats (headed by the A if vul, and by 2 honors if NV).
Anything goes in 3rd position, while it shows a solid suit in 4th position.
--> 2♣ opening with heavy preempts in the suit,
--> 3♣/3♦/3♥, therefore, are preempts in the next suit, or weak 2-suiters, 5-11 HCP. Specifically...
--> 3♣ == ♦ preempt, or 5-5+ majors
--> 3♦ == ♥ preempt, or weak with ♠ + minor
--> 3♥ == ♠ preempt, or weak with 6-5 minors
3♣ opener [♦ preempt or 5-5+ ♥-♠'s 5-11]
3♣ --> 3♦ to play --> PASS or 3♥ with 2-suiter
3♦ opener [♥ preempt or 5-5+ ♠/m 5/11]
3♦ --> 3♥ to play --> PASS or 3♠ with 2-suiter
3♥ opener [♠ preempt or 5-5+ ♣/♦ 5/11]
3♥ --> 3♠ to play --> PASS or 3NT with 2-suiter
3♠ opener [♣ or ♦ preempt, 8 cards 5/11]
3♠ --> 3NT ask ctrl in preempt suit --> 4♣ = 0, 4♦ = 1, 4♥ = 3
4♣ is P/C
3NT opener == solid 7-8 cards minor suit without side stop
3NT --> PASS
4♣ is P/C
4♦ == relay --> 4M == sing M
4NT == sing other m --> 5♣ is P/C
5m == 7.2.2.2 (m suit 7th)
5M == 8.3.1.1 sing in M and other m
5NT == 8.3.1.1 sing in both M