This bidding system has a strong notrump opening that does not contain a 5-card
major. We use the BTU continuations after the 1NT opening: Stayman takes care
of invitation with 5+ spades.
BTU reuses 4♠ for QUANT. This fills the blank that Gerber and Texas leave.
Standard QUANT usually invites the upper 1/2 to 2/3 of the opening range. This
4♠ serves as a narrower QUANT than 4NT or 5NT by only inviting the top 1/3.
There are 3 ways to bid 5-5 majors in BTU 1NT: 3♥♠ and via transfers. There is
more than one version in BTU. I am demonstrating my recommendation here step by
step.
There are 4 levels of 5-5 majors: weak, invitational, choice of games, and slam
try.
Weak: transfer to the better major and pass. Give up on the other one.
Invitational: anything goes except 3♠.
FG+: anything goes.
Hands around the game level are prone to interference. On the other hand,
leaking opener’s shape can be helpful in slam bidding. As a result, I
recommend the following bidding structure: