or weak (<26zp) with 2x4+M
or balanced 22-23hp
Answers - undisturbed
If opener rebids 2NT, showing the strong balanced hand, Niemeyer can be started (3♣) when holding at least a 3card M. Indeed, the opener possibly holds a 5 card major.
A partner with 8+hps may show slem ambition , especially when holding a 5+ card.