1-1♠-1NT

After this start, Opener's shape and strength are known to a great extent, much more so than over a classic 1m-1M-1NT start; there are only 3 possible shapes owner can have. Also, 1-1♠-2 is never used. So, instead of 1 or 2 way New Minor Forcing, we use 2ALERT as the checkback bid.

The basic idea is that Responder now bids 2ALERT to imply invitational with 5 spades, and Opener responds with something about his hand; using 2♠ as any minimum (2M in a 5-2 fit scores better than 2NT). Responder's bid over 2♠ now creates a force. With 2 and 2 now freed up, we use them for bad Responder hands with 4 spades and a longer minor that would rather play 2m than 1NT.

The full suggested menu is:

Developments after 2