The modern Precision trend is to require six to open 2C. That helps responder judge fit, though there is the issue of 4-card majors in 2C, since opener could be 4-6.
In Precision
4-5 hands are opened 1D. Say 4-1-3-5.
or 2D with 4-3-1-5 if you do that.
4-2-2-5 might open 1NT (14-16) or 1D.
1D is not available to us, so we have to open 2m on a 5-carder. That will only be on hands with 4-cards in the other minor. Since these are less common than the 6+ 1-suiters, responder tends to assume six in deciding whether to raise.
With that in mind, when we open 2m on a 5-carder, the suit will be “good”, so prepared for a doubleton raise. With a dull suit, open 1NT or pass if minimum.
S-Kxx H-x D-Axxxx C-KQxx
So we open 1NT with this “12-15, no 4-card major, may have a singleton major”
One issue is whether opener can bid 2S over a 2D transfer to show this hand. What about the same with a 15-count?
If 2H does not appeal, maybe 2S most of the time, 2NT with a 15-count.
Note that a super-accept of 2NT can show something else, a 15-count with 3 trumps. We do that from concern about the 15+10 game. Maybe that hand should bid 3m or 3H, then 2NT will be a 15-count with two trumps, occasionally one. We don’t play re-transfers.
No such option after a transfer to spades. Have to accept with a singleton, unless 1-3-5+4 super max
