A few years ago, I submitted a question here about opening a balanced hand in the so-called "no man's land" of 18-19 HCP, ie. too strong to open 1NT and too weak to open 2NT. Many thanks to those who responded.
Since then, I have learned to open one club with such a hand, and my partner responds in one of the following two ways depending on her HCP. With less than 7p, she bids one diamond, which we both understand as a denial. With 7 points or more, she bids as she would normally, and I rebid with 2NT. That bid is forcing to game, as the sum of the partnership's HCP (18+7) is at least 25, the minimum required for a game. The rest of the bidding is fairly straightforward thereafter.
My question is what should I rebid if partner's first response is the one diamond denial mentioned above ? Of course, any other thoughts about how to bid such a "no man's land" balanced hand of 18-19 HCP will be most welcome, especially within the restraints of Standard American.