ahydra, on 2018-February-13, 19:17, said:
This, absolutely. I've recently been playing in a flurry of one-off partnerships and insist on defining 2C-2NT as "does not exist" (I think on one CC I put "asking for a new partner" !) for the reasons Tramticket gives above. 2M, 3m = natural, positive, good suit; otherwise, bid 2D.
ahydra
I agree with both ahydra and the tramticket post to which ahydra refers.
The more discipline imposed on direct positive responses the better as far as I'm concerned. In exchange for taking valuable bidding space with the positive, you also convey some information about the responding hand to the 2
♣ hand to compensate. For me, a direct 2 M is 5+ cards to 2 honors with 1 1/2 QT+ in hand. Likewise, a direct 3 m is 5+ cards with 2 of top 3 honors and 2 QT+ in hand. You'd be surprised how often that kind of information can be of value in deciding about game/slam, small slam/grand slam, or, even the right strain for the contract.
Defaulting to 2
♦ with less than any agreed holding for a positive isn't all bad either. First, as tramticket points, it leaves maximum space for 2
♣ bidder to describe their hand. That adheres to a principle of good bidding of getting out of the way of the big hand to let them tell their story. Second, if responder does subsequently show a suit feature it is limited to less than a direct positive response.
If you use 2
♦ as waiting along with a defined "second negative" (cheapest suit, cheapest minor, etc.), then 2 NT, when available, becomes an "unspecified positive" 5-20 value. OP stated they showed controls, but even with the 0-1 controls shown by 2
♦, responder may or may not have values. So, maybe, OP should discuss with his partner a "second negative" over 2
♦. Then, 2 NT could naturally fall into the role of an unspecified positive.