[OscarKwok]

I play precision with my regular partner.
We know MeckWell play
1D->2H = 5S4H, less than invite
1D->2S = 5S4H, invite
but we have not try it.

Recently, my partner suggest:
1D-> 2H=5H4S, invitational hand
1D-> 2S=5S4H, invitational hand
for 5H-5S hand, shd bid 2H first.
for 64 major, may use 2H/S also.

So that
1D -> 1S -> 1NT -> ?
2C=check back
2D=to play
2H=non-forcing
2S=6+ cards Spade, non-forcing
&
1D -> 1H -> 1NT -> ?
2C=check back
2D=to play
2H=6+ Heart, non-forcing
2S= 4+S, reverse, game force.

Any comments?

[kfgauss]

This convention (called reverse flannery) is a somewhat common bidding gadget, used somewhat independent of system (i.e. it's not precision-specific).

The point of the convention is that one can't really show 5♠-4♥ hands easily with standard bidding, especially if partner now bids 2 of a minor. However, 4♠-5♥ hands are quite easy, as you can find a spade fit over your 1♥ response, so if partner bypasses 1♠ to bid 2m you know you can ignore spades. In either case, there isn't much of an issue over a 1N rebid, as checkback stayman can be used on invitational hands, and with the weak 5♠-4♥ hands you can pass, rebid 2H, or rebid 2S as you see fit. (I guess there's a slight gain from having 2H on this auction promise 5-5 if you adopt this, but that's pretty minor.)

As with any convention, there are all sorts of follow-ups to deal with, and the gain is pretty infrequent. Unless you're really fine-tuning things, I wouldn't recommend playing this (and other meanings for 2H and 2S may arguably be better anyways).

Andy

[awm]

I highly recommend playing two-way checkback over 1NT rebids in precision. Basically the method is 1♦ - 1M - 1NT...

2♣ = forces partner to bid 2♦, shows either a diamond signoff or various invitational hands
2♦ = artificial and game forcing (can play this as a relay or just natural followups)
2♥ = NF
2♠ = NF if original major was spades

There are actually a lot of options for followups, using 2NT as puppet to 3♣ or as natural invite, and various uses for the jump shifts and so forth. This method loses little to nothing against the checkback scheme you propose. Many people play a similar scheme over a natural 1♣ opening and 1NT rebid as well, but this has more downside as you lose the ability to sign off in 2♣.

Anyways, playing this method there is really no issue with 5-4 majors hands over the 1NT rebid. The problem case is the auctions 1♦-1M-2♣ and 1♦-1M-2♦. Of course, if the original major is hearts then opener's rebid should deny four spades. But there are various hands for opener where finding a 4-4 heart fit is really important:

x
KQxx
Axxx
AJxx

x
AKxx
KQxxxx
xx

Most precision players open 1♦ and rebid 2♣ on the first hand, and open and rebid ♦ on the second (of course the same applies to standard players). If responder has a less than game forcing hand with 5♠ and 4-5♥, it's easy to miss the heart fit. Playing reverse flannery here also frees up 1♦-1♠-2♦-2♥ as an artificial forcing bid, which can help in those auctions.